TECHNICAL FIELD 
     The present invention relates to a thermoelectric conversion element and a producing method thereof. 
     BACKGROUND ART 
     An element in which a Peltier effect or a Seebeck effect is utilized is used as a thermoelectric conversion element. The thermoelectric conversion element has a simple structure, and the thermoelectric conversion element is easily handled to be able to maintain a stable characteristic. Therefore, the thermoelectric conversion element attracts attention of a wide variety of applications. Particularly, because the thermoelectric conversion element can perform to cool a limited part and to control a temperature of the limited part near room temperature, accurately, as an electronic cooling element, researches are widely conducted toward applications of optoelectronics and a an isothermal treatment of a semiconductor laser. 
     Conventionally, as illustrated in  FIG. 8 , in configuration of the thermoelectric conversion element used in electronic cooling and thermic generation. Plural pn junction pairs are arrayed in series, the pn junction pair being configured so that p-type thermoelectric material  804  is in contact with n-type thermoelectric material  805  through junction electrode  806 . In  FIG. 8 , the sign  803  designates a substrate, the sign  801  designates a current introduction terminal (positive electrode), the sign  802  designates a current introduction terminal (negative electrode), and the sign H designates an arrow that indicates a heat flow direction. The thermoelectric conversion element illustrated in  FIG. 8  is configured such that, depending on a direction of a current passed through a junction portion, one end portion is heated while the other end portion is cooled. 
     A material that has a large performance index Z in a usage temperature range is used as the thermoelectric conversion element. The performance index Z is expressed by a Seebeck coefficient “a” that is of a unique constant of a substance, a specific resistance “r”, and a thermal conductivity “K” (Z=a 2 /rK). Usually, a Bi 2 Te 3  system material is used in the thermoelectric conversion element, and a crystal of the Bi 2 Te 3  based material has a significant cleavage property. Therefore, when the thermoelectric conversion element is subjected to processes such as slicing and dicing in order to obtain the thermoelectric conversion element from an ingot, a yield may be significantly degraded due to a crack and a chip. 
     The following method is attempted to solve the problem. The method is for producing a thermoelectric conversion module comprising the steps of: mixing, a material powder having a desired composition; heating and melting the material powder; solidifying the melted material powder to form a solid solution ingot of a thermoelectric semiconductor material having a rhombohedral structure (hexagonal structure); crushing the solid solution ingot to form solid solution powders; homogenizing particle diameters of the solid solution powders; pressurizing and sintering the solid solution powders whose particle diameters are homogenized; and, plastically deforming and flatting the powder sintered body under a hot condition to orient a crystal of the powder sintered body toward a crystal orientation in which an excellent performance index is obtained (a step of hot upset forging) (for example, see PTL 1). 
     A shape of each thermoelectric material chip used as the thermoelectric conversion element is a cuboid whose one side ranges from hundreds micrometers to several millimeters. Recently, in the thermoelectric conversion element that is used under near room temperature including a temperature difference of tens degrees, it is said that the thermoelectric conversion element having the size and thickness of tens to hundreds micrometers has high performance (for example, see NPL 1). 
     The number of pn junction pairs in one thermoelectric conversion element is up to hundreds, and density of the pn junction pair is up to tens pairs/cm 2 . Increasing the number of pn junction pairs becomes a necessary factor in order to improve thermoelectric conversion performance and in order to extend applications of the thermoelectric conversion element. Particularly, in power generation in which a small temperature difference is utilized, a generated electromotive force is proportional to the number of pn junction pairs. Therefore, desirably the number of pn junction pairs that are connected in series in the thermoelectric conversion element is increased as many as possible in order to take out a high voltage from the thermoelectric conversion element. 
     In the case in which the thermoelectric conversion element is used as a cooling element or a temperature control element, a current passed through the thermoelectric conversion element is increased with decreasing number of series-connected thermoelectric material chips. Therefore, it is necessary to make wiring or a power supply larger. Accordingly, desirably the number of series-connected thermoelectric material chips is increased as many as possible. 
       FIGS. 9A to 9E  illustrate a conventional method for producing the thermoelectric conversion element in which the number of thermoelectric material chips per unit area (chip density) is increased while the size of the thermoelectric material chip is reduced. 
     In a bump forming process (a), solder bumps  602  are formed in both surfaces of plate-like or rod-shaped p-type or n-type thermoelectric material wafer  601 . In an electrode wiring process (b), electrode wiring  301  is formed in a surface of substrate  101 . In connecting process (c), thermoelectric material wafer  601  in which solder bumps  602  are formed through the bump forming process (a) is disposed in the face of substrate  101 . Then electrode wiring  301  on substrate  101  and thermoelectric material wafer  601  are connected by soldering.  FIG. 9C  illustrates the connecting of p-type or n-type thermoelectric material wafer  601  and electrode wiring  301  on substrate  101 . For example, when  FIG. 9C  illustrates the connecting of p-type thermoelectric material wafer  601  and electrode wiring  301  on substrate  101 , similarly n-type thermoelectric material wafer  601  and electrode wiring  301  on substrate  101  are also connected. 
     In a cutting and removing process (d), connected thermoelectric material wafer  601  is cut and removed as needed basis such that electrode wirings  301 , to which different types of thermoelectric material chips should be connected, emerge. Through the cutting and removing process (d), substrate  101  is prepared. On the substrate  101 , p-type thermoelectric material chip  603  is connected to predetermined electrode wiring  301 , and electrode wiring  301 , to which n-type thermoelectric material chip  603  should be connected, emerges on the surface of substrate  101 . Similarly, substrate  101  is prepared. On substrate  101 , n-type thermoelectric material chip  603  is connected to predetermined electrode wiring  301   n , and an electrode, to which a p-type thermoelectric material chip should be connected, emerges on the surface of substrate  101 . 
     In an assembling process (e), for two substrates  101 , surfaces, to each of which thermoelectric material chip  603  is connected, face each other. Thermoelectric material chips  603  are aligned to predetermined positions where thermoelectric material chips  603  should be connected with electrode wirings  301 . A tip end of thermoelectric material chip  603  of one of substrates  101  is connected to electrode wiring  301 , which corresponds to the chip, on the other substrate  101 . Therefore, the thermoelectric conversion element including the pn junction pair in which the metallic electrode is interposed therebetween is formed (see PTL 2). 
     However, because a wafer is cut and removed to prepare the thermoelectric material chip whose section is small in a surface which is parallel to the substrate of the thermoelectric material chip, the conventional configuration has a problem in that the chip is broken during the cutting and removing process and during use. Additionally, the thermoelectric material chip is prepared by cutting and removing the wafer, which results in another problem in that the yield of the thermoelectric material is degraded. 
     In addition to the above thermoelectric conversion element, there is well known a thermoelectric conversion element in which p-type thermoelectric conversion material layers and n-type thermoelectric conversion material layers are alternately stacked with an insulating layer such as the substrate interposed therebetween. A thermoelectric conversion element, in which the p-type thermoelectric conversion material layers and the n-type thermoelectric conversion material layers are electrically connected in series at ends of the layers, is well known as the stacked type thermoelectric conversion element (for example, see PTLs 3 to 9). A thermoelectric conversion element, in which the p-type thermoelectric conversion material layers and the n-type thermoelectric conversion material layers are electrically connected in series at end portions of the layers in a direct manner or by surface contact in which a conductive layer is interposed, is also well known as the stacked type thermoelectric conversion element (for example, see PTLs 10 to 12). A method for forming the Bi 2 Te 3  based material on the insulating substrate such as polyimide by sputtering is well known as a method for forming the layer of the thermoelectric conversion material (for example, see PTLs 13 and 14 and NPL 2). 
     CITATION LIST 
     Patent Literature 
     
         
         [PTL 1] 
         Japanese Patent No. 3958857 
         [PTL 2] 
         Japanese Patent No. 3592395 
         [PTL 3] 
         Japanese Patent Application Laid-Open No. 8-222770 
         [PTL 4] 
         Japanese Patent Application Laid-Open No. 11-274581 
         [PTL 5] 
         Japanese Patent Application Laid-Open No. 2008-205181 
         [PTL 6] 
         Japanese Patent Application Laid-Open No. 50-141287 
         [PTL 7] 
         U.S. Pat. No. 3,930,303 
         [PTL 8] 
         International Publication No. 05/047560 
         [PTL 9] 
         U.S. Patent Application Publication No. 2005/0178424 
         [PTL 10] 
         Japanese Patent Application Laid-Open No. 1-93182 
         [PTL 11] 
         U.S. Pat. No. 5,055,140 
         [PTL 12] 
         U.S. Patent Application Publication No. 2010/0116308 
         [PTL 13] 
         Japanese Patent Application Laid-Open No. 2006-86510 
         [PTL 14] 
         Japanese Patent No. 3927784 
       
    
     Non Patent Literature 
     
         
         [NPL 1] 
         IEICE Transactions C Vol. J75-C2 No. 8 pp. 416-424 
         [NPL 2] 
         Mitsuyoshi Sakai et al., “Development and research of thermoelectric module on Be—Te based thin film”, Proceedings of thermoelectric conversion symposium 2003 (thermoelectric conversion workshop), 2003, p. 24-25 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     An object of the invention is to provide a thermoelectric conversion element, having many pn junction pairs per unit area and a thermoelectric material chip which is hardly broken, and a producing method thereof. 
     Solution to Problem 
     The following thermoelectric conversion element is provided in order to achieve the object. 
     (1) A thermoelectric conversion element comprising: 
     alternate layers of p-type thermoelectric material layers and n-type thermoelectric material layers; 
     a plurality of substrates disposed between adjacent layers of the p-type thermoelectric material layers and n-type thermoelectric material layers; 
     contact holes respectively provided in the plurality of substrates such that the contact holes appear alternately at opposite ends, in a direction perpendicular to a direction of arrangement of the p-type thermoelectric material layers and the n-type thermoelectric material layers, of the substrates; and
 
a conductive material disposed in the contact holes for electrically connecting the adjacent layers of the p-type thermoelectric material layers and the n-type thermoelectric material layers.
 
(2) The thermoelectric conversion element described in (1), further comprising high heat-transfer films between adjacent pairs of the plurality of substrates and the p-type thermoelectric material layers.
 
(3) The thermoelectric conversion element described in (1), further comprising high heat-transfer films between adjacent pairs of the plurality of substrates and the n-type thermoelectric material layers.
 
(4) The thermoelectric conversion element described in any one of (1) to (3), wherein the plurality of substrates consist of alternate layers of a first substrate and a second substrate, the first substrate having one or more of the p-type thermoelectric material layers formed thereon, the second substrate having one or more of the n-type thermoelectric material layers formed thereon.
 
(5) The thermoelectric conversion element described in (4), wherein the first substrates include the p-type thermoelectric material layers which are divided into two or more individual segments formed thereon, and the second substrates include the n-type thermoelectric material layers which are divided into two or more individual segments formed thereon.
 
(6) The thermoelectric conversion element described in any one of (1) to (3), wherein both of the p-type thermoelectric material layers and the n-type thermoelectric material layers on the plurality of the substrates are divided into two or more individual segments, respectively.
 
(7) The thermoelectric conversion element described in any one of (1) to (6), wherein the conductive material includes a projection projecting from the contact hole along the direction of arrangement of the p-type thermoelectric material layers and the n-type thermoelectric material layers, the projection creating a gap between each of adjacent pairs of the p-type thermoelectric material layers and the plurality of substrates or between each of adjacent pairs of the n-type thermoelectric material layers and the plurality of substrates.
 
     The following thermoelectric conversion element producing method is provided in order to achieve the object. 
     (8) A method for producing a thermoelectric conversion element, comprising: 
     providing a p-type thermoelectric material layer on one side of a first substrate while making a first contact hole in one end of the first substrate, the first contact hole penetrating through the first substrate; 
     providing an n-type thermoelectric material layer on one side of a second substrate while making a second contact hole in one end of the second substrate, the second contact hole penetrating through the second substrate; and 
     stacking the first substrate and the second substrate on top of each other such that the p-type thermoelectric material layer and the n-type thermoelectric material layer appear alternately with the first or second substrate interposed therebetween, and that the first contact hole and the second contact hole appear alternately on opposite ends, in a direction perpendicular to a direction of arrangement of the p-type thermoelectric material layers and the n-type thermoelectric material layers, of the substrates,
 
wherein adjacent pairs of the p-type thermoelectric material layer and the n-type thermoelectric material layer are electrically connected through the contact hole.
 
(9) The method described in (8), wherein the step of providing the p-type thermoelectric material layer and the n-type thermoelectric material layer respectively on the first substrate and the second substrate is followed by the step of making the first contact hole and the second contact hole respectively in the first substrate and the second substrate,
 
the method further comprises disposing a conductive material in the first contact hole and the second contact hole for electrically connecting the adjacent pairs of the p-type thermoelectric material layer and the n-type thermoelectric material layer.
 
(10) The method described in (8), wherein the step of making the first contact hole and the second contact hole respectively in the first substrate and the second substrate is followed by the step of providing the p-type thermoelectric material layer and the n-type thermoelectric material layer respectively on the first substrate and the second substrate;
 
wherein the adjacent pairs of the p-type thermoelectric material layer and the n-type thermoelectric material layer are electrically connected by the p-type thermoelectric material layer and the n-type thermoelectric material layer, the p-type thermoelectric material layer and the n-type thermoelectric material layer extending as far as to backsides of the first substrate and second substrate through wall surfaces of the first contact hole and the second contact hole.
 
     Advantageous Effects of Invention 
     In the invention, the thermoelectric conversion element comprises the alternate layers of the p-type thermoelectric material layers and the n-type thermoelectric material layers, and the plurality of substrates disposed between adjacent layers of the p-type thermoelectric material layers and n-type thermoelectric material layers. Therefore, the number of pn junction pairs per unit area can be increased, and the breakage of the thermoelectric material chip can be suppressed. 
     In the invention, the contact holes are alternately disposed at opposite ends of the substrates in the direction perpendicular to the direction of arrangement of the p-type thermoelectric material layers and the n-type thermoelectric material layers, and the conductive material is disposed in the contact holes. The stress applied to each thermoelectric material layer is reduced, because each thermoelectric material layer and the conductive material come easily and securely into contact with each other when the substrates are stacked. Therefore, the substrate and each thermoelectric material layer can be formed thinner. Accordingly, the number of pn junction pairs per unit area can be increased. 
     In the thermoelectric conversion element of the invention, 
     the plurality of substrates are disposed between adjacent layers of the p-type thermoelectric material layers and n-type thermoelectric material layers, and the contact holes are disposed alternately at opposite ends of the substrates. Therefore, productivity is enhanced in the thermoelectric conversion element of the invention compared with the case in which the p-type thermoelectric material layer and the n-type thermoelectric material layer, which are alternately stacked with the substrate interposed therebetween, are connected by the electrode formed at the edge like the conventional thermoelectric conversion element. 
     According to the thermoelectric conversion element of the invention, the number of pn junction pairs per unit area is increased because the p-type thermoelectric material layers and the n-type thermoelectric material layers are formed into a layered shape. Therefore, the high output can be obtained. Because the plurality of substrates are disposed between adjacent layers of the p-type thermoelectric material layers and n-type thermoelectric material layers, reliability degradation caused by the breakage of the thermoelectric material can be prevented irrespective of the thermoelectric material. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view illustrating a schematic configuration of a thermoelectric conversion element according to Embodiment 1 of the invention. 
         FIG. 2  is a view illustrating a schematic configuration of a thermoelectric conversion element according to Embodiment 2 of the invention. 
         FIG. 3  is a view illustrating a method for producing the thermoelectric conversion element according to Embodiment 2 of the invention. 
         FIG. 4  is a view illustrating another method for producing the thermoelectric conversion element according to Embodiment 2 of the invention. 
         FIG. 5  is a view illustrating a schematic configuration of a thermoelectric conversion element according to Embodiment 3 of the invention. 
         FIG. 6  is a view illustrating a schematic configuration of a thermoelectric conversion element according to Embodiment 4 of the invention. 
         FIG. 7  is a view illustrating a method for producing the thermoelectric conversion element according to Embodiment 4 of the invention. 
         FIG. 8  is a perspective view of a conventional thermoelectric conversion element described in PTL 1. 
         FIG. 9  is a view illustrating a method for producing a conventional thermoelectric conversion element described in PTL 2. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Now, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, particularly “p” is affixed to a configuration relating to a p-type thermoelectric material layer, and “n” is affixed to a configuration relating to an n-type thermoelectric material. 
     Embodiment 1 
       FIGS. 1A and 1B  are a schematic configuration of thermoelectric conversion element  100  according to Embodiment 1 of the invention.  FIG. 1A  is a perspective view, and  FIG. 1B  is a sectional view taken on a line A-A of  FIG. 1A . 
     As illustrated in  FIG. 1 , thermoelectric conversion element  100  of Embodiment 1 includes plural substrates  101  (i.e., p-substrates  101   p  and n-substrates  101   n ), and alternate layers of p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n . The plurality of substrates  101  are disposed between adjacent layers of p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n . The plurality of substrates  101  have contact holes  103  such that contact holes  103  are disposed alternately at opposite ends, in the direction perpendicular to the direction of arrangement of p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n , of substrates  101 . In  FIG. 1 , the sign X designates the direction of arrangement of p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n . In  FIG. 1 , the sign Y designates the direction perpendicular to the X-direction. In  FIG. 1 , the sign Z designates a direction orthogonal to both the X-direction and the Y-direction. 
     For example, substrate  101   p , that is adjacent to p-type thermoelectric material layer  102   p  on one side in the X-direction, includes contact hole  103   p  in one end portion in the Y-direction. On the other hand, substrate  101   n , that is adjacent to p-type thermoelectric material layer  102   p  on the other side in the X-direction, includes contact hole  103   n  in the other end portion in the Y-direction. Conductive material  104  is disposed in contact hole  103 , and conductive material  104  electrically connects the adjacent layers of p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n , which are adjacent to each other with substrate  101  interposed therebetween. 
     Preferably substrate  101  is formed into a film shape. Use of the thin film as substrate  101  can reduce an occupied volume of an insulating substrate in the thermoelectric conversion element, and an occupied volume of a thermoelectric material can be increased. Therefore, the number of pn junction pairs per unit area can be increased, and a higher-voltage output can be obtained. 
     Preferably a material having a high heat-resistant property is used as a material of substrate  101 . The material of substrate  101  may be an inorganic material or a heat-resistant resin such as polyimide. The material having the high heat-resistant property is used as the material of substrate  101 , which allows a temperature range to be widened to a higher temperature during production and use of the thermoelectric conversion element. For example, a polyimide film having a thickness of 1 to 100 um can be used as substrate  101 . As to dimensions of substrate  101 , for example, a length in the Y-direction ranges from 1 to 5 mm, and a length in the Z-direction ranges from 10 to 50 mm. 
     Each of p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n  is a material layer in which an electromotive force is generated when a temperature difference is generated at both ends thereof. A material for the thermoelectric material layer can be selected according to the temperature difference that is generated during use of the thermoelectric conversion element. For example, a bismuth-tellurium based material (Bi—Te based material) can be used as the material when the temperature difference ranges from room temperature to 500 K, a lead-tellurium system (Pb—Te system) can be used as the material when the temperature difference ranges from room temperature to 800 K, and a silicon-germanium system (Si—Ge system) can be used as the material when the temperature difference ranges from room temperature to 1,000 K. 
     For example, the materials for the p-type and n-type thermoelectric material layers can be obtained by adding a proper dopant to the above material. An example of the dopant, used to obtain the material of the p-type thermoelectric material layer, may include Sb. An example of the dopant, used to obtain the material of the n-type thermoelectric material layer, may include Se. The above material forms a mixed crystal by the addition of the dopant. Accordingly, the dopant is added to the above material in an amount of such that the dopant is expressed in a composition formula of the above material such as “Bi 0.5 Sb 1.5 Te 3 ” and “Bi 2 Te 2.7 Se 0.3 ”. 
     Preferably the Bi—Te based material that is of the material having excellent performance around room temperature is used as the thermoelectric materials for p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n.    
     There is no particular limitation to the thicknesses of thermoelectric material layers  102  and  103 . From the viewpoint of increasing the number of pn junction pairs per unit area and obtaining the higher-voltage output, a thin thermoelectric material layer  102  is preferable. From this point of view, an example of the preferable thermoelectric material layer may include a layer having the thickness of 400 to 500 nm. On the other hand, a thick thermoelectric material layer  102  is preferable because a simpler, low-cost process can be selected in forming thermoelectric material layers  102  and  103 . Such a thermoelectric material layer having a relatively large thickness can be formed by offset printing, inkjet printing, and plating. 
     Contact hole  103  is made in substrate  101 . At least one contact hole  103  is formed in one end portion or the other end portion in the Y-direction of one p-type thermoelectric material layer  102   p  or one n-type thermoelectric material layer  102   n . One contact hole  103  is preferably made per thermoelectric material layer from the viewpoint of simplification of the process. However, at least two contact holes  103  may be made per thermoelectric material layer, for example, from the viewpoint of stability of a contact state between the substrates stacking one another. There is no particular limitation to a diameter of contact hole  103 . However, from the view point of sufficiently introducing conductive material  104  to the inside of contact hole  103 , preferably the diameter of contact hole  103  is not lower than 0.8 time the thickness of substrate  101 , more preferably the diameter of contact hole  103  is 1 to 10 times the thickness of substrate  101 . 
     In the X-direction, conductive material  104  disposed in contact hole  103  is in contact with both p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n , which are adjacent to each other with substrate  101  interposed therebetween. Contact hole  103  may be filled with conductive material  104 , or an inner peripheral wall of contact hole  103  may be covered with conductive material  104 . There is no need to cover a whole surface of the inner peripheral wall of contact hole  103  with conductive material  104 , but it is only necessary that conductive material  104  connects p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n , which are adjacent to each other with substrate  101  interposed therebetween, along an axial direction (X-direction) of contact hole  103 . 
     For example, conductive material  104  is: a conductive paste such as an Ag paste with which contact hole  103  is filled; a metallic layer such as Cu with which the inner peripheral wall of contact hole  103  is covered; p-type or n-type thermoelectric material layer  102  or  103  which is formed from the surface of substrate  101  such that the inner peripheral wall of contact hole  103  is covered with p-type or n-type thermoelectric material layer  102  or  103 ; or a combination of at least two thereof. 
     The thermoelectric conversion element of Embodiment 1 can be produced as follows. P-type thermoelectric material layer  102   p  is formed on substrate  101   p  by, for example, sputtering. Similarly n-type thermoelectric material layer  102   n  is formed on substrate  101   n  by the sputtering. 
     For example, polyimide having the thickness of 50 um is used as substrate  101 . On substrate  101 , for example, a layer made of (Bi 2 Te 3 ) 0.25 (Sb 2 Te 3 ) 0.75  having the thickness of about 25 to about 30 um is formed as p-type thermoelectric material layer  102   p  by the sputtering, and a layer made of Bi 2 Te 2.7 Se 0.3  having the thickness of about 25 to about 30 um is formed as n-type thermoelectric material layer  102   n  by the sputtering. A target that is prepared by mechanical alloying and pulsed electric current sintering can be used as a target for each thermoelectric material (for example, see NPL 2). In forming p-type and n-type thermoelectric material layers  102   p  and  102   n , an RF sputtering apparatus is used, and Ar is used as a sputtering gas. As to sputtering conditions, for example, an output is 40 W, and an Ar gas pressure is in the range from 1×10 −1  to 1.5×10 −1  Pa. 
     After the sputtering, substrate  101  including p-type and n-type thermoelectric material layers  102   p  and  102   n  may be heated in air, in vacuum, or in an inert gas such as a nitrogen gas. Through the heating, p-type and n-type thermoelectric element layers  102   p  and  102   n  are stabilized, and electric resistances of p-type and n-type thermoelectric element layers  102   p  and  102   n  are decreased. Therefore, performance of p-type and n-type thermoelectric element layers  102   p  and  102   n  can be improved. 
     Then, contact hole  103   p  is made in an end portion of substrate  101   p , and contact hole  103   n  is made in an end portion of substrate  101   n . For example, contact hole  103  is made by a usual perforation method such as processing by a laser and a drill, punching, and etching. 
     Then, conductive material  104  is disposed in contact hole  103 . For example, contact hole  103  is filled with the conductive paste, or contact hole  103  is plated with metal, which allows conductive material  104  to be disposed in contact hole  103 . 
     Then, substrates  101   p  and substrates  101   n  are alternately disposed, and therefore p-type thermoelectric material layers  102   p  and n-type thermoelectric material layers  102   n  are alternately disposed with substrate  101  interposed therebetween. At this point, when contact hole  103   p  is disposed in one end portion in the Y-direction of substrate  101   p , contact hole  103   n  is disposed in the other end portion in the Y-direction of substrate  101   n.    
     Along the X-direction, contact holes  103  made in substrates  101  are alternately disposed at one end portion and the other end portion in the Y-direction by the stacking. As a result, p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n , which are adjacent to each other with substrate  101  interposed therebetween, are electrically connected in series. 
     Preferably a disposed structure described above is integrated in the thermoelectric conversion element. The disposed structure can be integrated such that an adhesive tape adheres to an end face in the Y-direction over the whole region in the X-direction. Alternatively, the disposed structure can be integrated such that disposed substrates  101  are bounded by a frame body. Alternatively, the disposed structure can be integrated such that p-type thermoelectric material layer  102   p , n-type thermoelectric material layer  102   n , and substrate  101 , which are in contact with one another, are bonded to one another by a bonding agent. 
     The thermoelectric conversion element is disposed such that the Y-direction of the thermoelectric conversion element is matched with a heat flow direction, which allows the thermoelectric conversion element to be used in power generation by the temperature difference. The thermoelectric conversion element can be used as a temperature control device by passage of a current. 
     The thermoelectric conversion element has the disposed structure in which p-type thermoelectric material layers  102   p  and n-type thermoelectric material layers  102   n  are alternately disposed with substrate  101  interposed therebetween. Therefore, the number of pn junction pairs per unit area can be increased, and the breakage of the thermoelectric material chip is hardly generated. 
     In the thermoelectric conversion element, p-type thermoelectric material layer  102   p  and n-type thermoelectric material layers  102   n  are electrically connected in series by conductive material  104  disposed in contact hole  103 . The thickness of conductive material  104  is easily controlled because conductive material  104  is disposed in contact hole  103 . Therefore, when substrates  101  are disposed, each thermoelectric material layer  102  and conductive material  104  are easily and securely in contact with each other. Therefore, because a stress applied to each thermoelectric material layer is reduced when substrates  101  are disposed, substrate  101  and each thermoelectric material layer  102  can be formed thinner. From this viewpoint, the number of pn junction pairs per unit area can be increased in the thermoelectric conversion element. 
     In the thermoelectric conversion element, an electrically-conducting path is formed in the end portion in the Y-direction of substrate  101  by conductive material  104  disposed in contact hole  103 . Different material layers are electrically connected in series by alternately stacking substrates  101  having the different material layers. Therefore, the thermoelectric conversion element can more easily be prepared compared with the conventional thermoelectric conversion element in which the electrodes are formed in the end faces of the stacking object of thermoelectric material layer and the substrate. Accordingly, high productivity is implemented. 
     The thermoelectric conversion element includes contact hole  103   p  that is made at one end portion in the Y-direction of substrate  101   p  and contact hole  103   n  that is made at the other end portion in the Y-direction of substrate  101   n . Therefore, the thermoelectric conversion element can obtain the high output because the temperature difference between contact hole  103   p  and contact hole  103   n  is ensured. 
     In the thermoelectric conversion element, the thermoelectric material layer is formed by the sputtering. The sputtering film is a thin film, and crystal grains of the thermoelectric conversion material constituting the sputtering film become fine. Therefore, in the thermoelectric conversion element, the number of pn junction pairs per unit area can be increased, and the higher output can be obtained. 
     Embodiment 2 
       FIGS. 2A and 2B  illustrate a schematic configuration of thermoelectric conversion element  200  according to Embodiment 2 of the invention.  FIG. 2A  is a perspective view, and  FIG. 2B  is a sectional view taken on a line A-A of  FIG. 2A . 
     As illustrated in  FIGS. 2A and 2B , plural substrates  101   p  and plural substrates  101   n  are alternately disposed in thermoelectric conversion element  200  of Embodiment 2. P-type thermoelectric material layer  102   p  is formed in the surface of each of substrates  101   p , and n-type thermoelectric material layer  102   n  is formed in the surface of each of substrates  101   n . Plural segments of p-type thermoelectric material layer  102   p  are formed in one substrate  101   p . Plural segments of n-type thermoelectric material layer  102   n  are formed in one substrate  101   n . As illustrated in  FIG. 2A , p-type thermoelectric material layers  102   p  and n-type thermoelectric material layers  102   n  are respectively arrayed in the Z-direction on each substrate  101 . Each segments of p-type thermoelectric material layer  102   p  and each n-type thermoelectric material layer  102   n  are formed into a strip, rectangular shape in the Y-direction, respectively. As to dimensions of each rectangular thermoelectric material layer  102 , for example, the length in the Y-direction ranges from 1 to 5 mm, and the length in the Z-direction ranges from 0.05 to 2 mm. 
     High heat-transfer films  105  having high thermal conductivity (for example, 50 W/{(m)×(K)} or more) are formed between substrate  101   p  and p-type thermoelectric material layer  102   p  and between substrate  101   n  and n-type thermoelectric material layer  102   n , respectively. High heat-transfer film  105  may be formed in a whole of one of surfaces of substrate  101 , or high heat-transfer film  105  may be plural strip rectangular films in the Y-direction, which are arrayed in the Z-direction similarly to the thermoelectric material layer as illustrated in  FIG. 2A . For example, a thin film or thick film, which is made of Ag (silver), Au (gold), Pd (palladium), Pt (platinum), or W (tungsten), can be used as high heat-transfer film  105 . The thickness of the thin film is, for example, 200 nm. 
     As illustrated in  FIG. 2B , each segments of p-type thermoelectric material layer  102   p  and each segments of n-type thermoelectric material layer  102   n  are electrically connected by conductive material  104   p  disposed in contact hole  103   p . Each segments of p-type thermoelectric material layer  102   p  and each segments of n-type thermoelectric material layer  102   n  are adjacent to each other with substrate  101 , for example, substrate  101   p , interposed therebetween. Contact hole  103   p  of substrate  101   p  is formed at one end portions in a lengthwise direction (Y-direction). Contact hole  103   n  of substrate  101   n  is formed at the other end portion in the lengthwise direction (Y-direction). 
     Contact hole  103  is filled with conductive material  104 . As illustrated in  FIG. 2B , conductive material  104  is projected from an end on one side (side of substrate  101 ) in the X-direction of contact hole  103 . Therefore, a gap exists between substrate  101  and p-type thermoelectric material layer  102   p  or n-type thermoelectric material layer  102   n , which exists on one side in the X-direction. 
     An example of a method for producing thermoelectric conversion element  200  of Embodiment 2 will be described below with reference to  FIGS. 3A to 3D . 
     A metal mask (not illustrated) is placed over polyimide substrate  101 , and high heat-transfer film  105  is formed into a predetermined shape on substrate  101  by, for example, the sputtering. 
     While the metal mask is placed, each of segments of p-type thermoelectric material layer  102   p  or each of segments of n-type thermoelectric material layer  102   n  is formed into the predetermined shape on high heat-transfer film  105  by the sputtering. In Embodiment 2, high heat-transfer film  105  and p-type thermoelectric material layer  102   p  or n-type thermoelectric material layer  102   n  are formed by the sputtering. Alternatively, high heat-transfer film  105  and p-type thermoelectric material layer  102   p  or n-type thermoelectric material layer  102   n  may be formed by an evaporation method or a plasma CVD method. 
     High heat-transfer film  105 , p-type thermoelectric material layer  102   p , and n-type thermoelectric material layer  102   n  are formed into the predetermined shape divided the surface shape of substrate  101  into plural segments by placing the metal mask over the substrate, respectively. Alternatively, after high heat-transfer film  105 , p-type thermoelectric material layer  102   p , and n-type thermoelectric material layer  102   n  are formed over the substantially whole surface of substrate  101 , high heat-transfer film  105 , p-type thermoelectric material layer  102   p , and n-type thermoelectric material layer  102   n  may partially be removed to divide into plural segments by laser irradiation, cutting, etching, and the like. 
     SUS 304 can be used as a material for the metal mask. However, the material is not limited to SUS 304. In consideration of a heat-resistant property and workability, the material for the metal mask may be selected according to an intended deposit condition or shape. 
     Then, contact hole  103  is made in substrate  101  on which thermoelectric material layer  102  is formed. A hole is pierced through substrate  101  by the method such as the processing by the laser and the drill, the punching, and the etching, thereby making contact hole  103 . The hole may be made by overlapping plural substrates  101  and piercing through all of the overlapped substances  101 , when the dispositions and shapes of p-type thermoelectric material layers  102   p  and n-type thermoelectric material layers  102   n  in each substrate  101  are symmetrical in each of the Y-direction and the Z-direction. 
     Then, conductive material  104  is disposed in contact hole  103 . For example, contact hole  103  is filled with the conductive paste such as the Ag paste, thereby disposing conductive material  104  in contact hole  103 . As illustrated in  FIG. 3C , an end of conductive material  104  on the side of the thermoelectric material layer is formed so as to be flush with the surface of contact hole  103 . A projection is projected from contact hole  103  at an end of the conductive material  104  on the side of substrate  101 . For example, a projected length of the projection ranges from 0.01 to 1 um. 
     For example, while or after contact hole  103  is filled with the conductive paste, a plate, having a hole whose diameter is substantially identical to that of contact hole  103  and a desired thickness, is overlapped with substrate  101  to surround contact hole  103  by the plate, and the excess paste is removed along the surface of the plate, and the plate is taken off from substrate  101 , which allows the projection to be formed. 
     Then, substrates  101   p  and substrates  101   n  are alternately disposed. Segments of p-type thermoelectric material layer  102   p  are formed in the surface of each of substrates  101   p , and segments of n-type thermoelectric material layer  102   n  are formed in the surface of each of substrates  101   n . At this point, contact hole  103   p  of substrate  101   p  is disposed at one end portion in the Y-direction. Contact hole  103   n  of substrate  101   n  is disposed at the other end portion in the Y-direction. 
     Each of segments of thermoelectric material layer  102   p  and each of segments of n-type thermoelectric material layer  102   n  are electrically connected in series along the X-direction with conductive material  104  interposed therebetween by stacking substrates  101 . Segments of p-type thermoelectric material layer  102   p  on one substrate  101   p  and segments of n-type thermoelectric material layer  102   n  on one substrate  101   n  are arrayed in the Z-direction, respectively. All of the disposed segments of thermoelectric material layer  102   p  and  102   n  constituting the disposed groups in the X-direction are electrically connected in series by conductive materials  104  disposed in contact holes  103 . 
     Similarly to the thermoelectric conversion element of Embodiment 1, each thermoelectric material layer and the substrate are integrated by the adhesion of the adhesive tape to the end face in the Y-direction, the binding by the frame body, or the bonding of the projection and the thermoelectric material layer by the bonding agent, thereby forming the thermoelectric conversion element. The thermoelectric conversion element is disposed such that the Y-direction of the thermoelectric conversion element is matched with a heat flow direction, which allows the thermoelectric conversion element to be used in the power generation by the temperature difference. The thermoelectric conversion element can be used as the temperature control device by the passage of the current. 
     The thermoelectric conversion element of Embodiment 2 has the same effect as that of Embodiment 1 in the same configuration as that of Embodiment 1. 
     Preferably only p-type thermoelectric material layer  102   p  is formed in substrate  101   p , and only n-type thermoelectric material layer  102   n  is formed in substrate  101   n . All the thermoelectric material layers are formed on one substrate  101  only by the p-type thermoelectric material layers or the n-type thermoelectric material layers. Therefore, the number of processes can be decreased in manufacturing the thermoelectric material compared with the case in which both the p-type and n-type thermoelectric material layers are formed on one substrate  101 . 
     In the thermoelectric conversion element, plural segments of p-type thermoelectric material layer  102   p  are formed on one substrate  101   p , and plural segments of n-type thermoelectric material layers  102   n  are formed on one substrate  101   n . Therefore, the number of pn junction pairs per unit area can further be increased, and the higher output can be obtained. 
     In the thermoelectric conversion element, conductive material  104  includes the projection projected from contact hole  103 . Therefore, the gap is formed between thermoelectric material layer  102  and substrate  101 . The existence of the gap can reduce the thermal conductivity between a high-temperature end and a low-temperature end of thermoelectric material layer  102  during the use of thermoelectric conversion element  200 , and the higher output can be obtained. 
     The thermoelectric conversion element also includes high heat-transfer film  105  that is provided between thermoelectric material layer  102  and substrate  101 . During the deposition of thermoelectric material layer  102 , the provided high heat-transfer film  105  promotes a crystal orientation of the thermoelectric material of thermoelectric material layer  102 . During the deposition of thermoelectric material layer  102 , the thermoelectric material is rapidly quenched on high heat-transfer film  105 , whereby a crystal grain of the thermoelectric material becomes finer. Therefore, the thermoelectric performance of the thermoelectric material layer  102  is further improved, and the higher output can be obtained. 
     In Embodiment 2, the Bi—Te based material is used as thermoelectric material layer  102 . There is no particular limitation to the material for thermoelectric material layer  102 , but the material may arbitrarily be changed according to a usage environment or an intended use of thermoelectric conversion element  200 . 
     In Embodiment 2, contact hole  103  is made after thermoelectric material layer  102  is deposited on substrate  101 . Alternatively, in the invention, contact hole  103  may be made in substrate  101  before thermoelectric material layer  102  is deposited. In this case, the electric conduction of contact hole  103  can simultaneously be established with formation of high heat-transfer film  105  and thermoelectric material layer  102  performed after perforation of contact hole  103 . 
     A method for establishing the electric connection will be described below by taking a embodiment, in which the thermoelectric material layer is directly formed on substrate  101 , as an example. 
     As illustrated in  FIGS. 4A to 4C , contact hole  103  is made in substrate  101  ( FIG. 4A ). Then thermoelectric material layer  102  is deposited by the sputtering. The thermoelectric material goes partially round to the back side of substrate  101  while adhering to the inner wall of contact hole  103 . Therefore, the thermoelectric material adheres to an opening edge (on the side of substrate  101  in the X-direction) of contact hole  103  ( FIG. 4B ). The thermoelectric material adhering to the opening edge forms the projection. That is, the thermoelectric material, that adheres to the inside of contact hole  103  and that forms the projection, constitutes the conductive material. 
     When substrates  101  including the thermoelectric material layers are disposed, the projection of the thermoelectric material is in contact with each thermoelectric material layer as illustrated in  FIG. 4C . Along the X-direction, the projections are alternately disposed in one end portion and the other end portion in the Y-direction. From the viewpoint of simplifying the process, the projection is more effectively made of the thermoelectric material. 
     In the method illustrated in  FIGS. 4A to 4C , the thermoelectric material layer may be deposited after contact hole  103  is made in substrate  101  including the high heat-transfer film  105 . According to the method, the thermoelectric conversion element, which includes high heat-transfer film  105  while the thermoelectric material is used as the conductive material, can be produced. 
     Conductive material  104  may further be disposed in contact hole  103  in which the thermoelectric material is disposed. In this case, the thermoelectric material also acts as an underlying layer of conductive material  104 . Therefore, effectively conductive material  104  is more strongly disposed in contact hole  103 . 
     The material for high heat-transfer film  105  is used instead of the thermoelectric material, and high heat-transfer film  105  is formed in substrate  101  in which contact hole  103  is made, which allows the material for high heat-transfer film  105  to be used as the conductive material similarly to the thermoelectric material in the above method. 
     Embodiment 3 
     In the thermoelectric conversion element of the invention, the p-type thermoelectric material layers and the n-type thermoelectric material layers are alternately disposed along the X-direction, the disposition of the contact hole may vary in the Y-direction, and the disposition of the thermoelectric material layer may vary in the Z-direction on the same substrate. 
     For example, in thermoelectric conversion element  300  illustrated in  FIG. 5 , p-type thermoelectric material layers  102   p  and n-type thermoelectric material layers  102   n  are alternately arrayed along the X-direction. On one substrate  101 ′, segments of p-type thermoelectric material layers  102   p  and segments of n-type thermoelectric material layers  102   n  are alternately disposed along the Z-direction, respectively. For example: a segment of p-type thermoelectric material layer  102   p  that includes contact hole  103   p  on one end side in the Y-direction; a segment of n-type thermoelectric material layer  102   n  that includes contact hole  103   n  on one end side; a segment of p-type thermoelectric material layer  102   p ′ that includes contact hole  103   p  on the other end side; and a segment of n-type thermoelectric material layer  102   n ′ that includes contact hole  103   n  on the other end side; are disposed along the Z-direction on one substrate  101 ′. Thus, the positions in the Y-direction of contact holes  103  of the thermoelectric material layers vary on one substrate  101 ′. Along the X-direction, contact holes  103  are alternately disposed in one end portion and the other end portion in the Y-direction. 
     Thermoelectric conversion element  300  can be produced by the method of  FIGS. 3A to 3D  except that segments of p-type thermoelectric material layers  102   p  and segments of n-type thermoelectric material layers  102   n  are alternately disposed along the Z-direction on substrate  101 ′ and that contact hole  103  is located in one end portion or the other end portion in the Y-direction according to a type of each thermoelectric material layer. Thermoelectric conversion element  300  of Embodiment 3 has the same effect as that of Embodiments 1 and 2 in the same configuration as that of Embodiments 1 and 2. 
     In the thermoelectric conversion element of the invention, the contact holes may alternately be disposed in one end portion and the other end portion in the Y-direction along the X-direction, and there is no need to form all the contact holes in one end portion in one substrate  101 . 
     In addition to the embodiment of  FIG. 5 , for example, on the same substrate, all contact holes  103   p  corresponding to p-type thermoelectric material layers  102   p  may be made in one end portion in the Y-direction of substrate  101  while all contact holes  103   n  corresponding to n-type thermoelectric material layers  102   n  are made in the other end portion in the Y-direction of substrate  101 . 
     Embodiment 4 
       FIGS. 6A and 6B  illustrate a schematic configuration of a thermoelectric conversion element according to Embodiment 4 of the invention.  FIG. 6A  is a perspective view, and  FIG. 6B  is a sectional view taken on a line A-A of  FIG. 6A . 
     As illustrated in  FIGS. 6A and 6B , plural substrates  101   a  in each of which p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   a  are formed in the surface thereof and plural substrates  101   b  in each of which the thermoelectric material layer  102  is not formed are alternately disposed in thermoelectric conversion element  400  of Embodiment 4. P-type thermoelectric material layer  102   p  is formed in one of two surfaces of substrate  101   a , and n-type thermoelectric material layer  102   n  is formed in the other surface of substrate  101   a.    
     In each thermoelectric material layer, similarly to Embodiment 2, the plural strip, rectangular layers in the Y-direction are arrayed along the Z-direction. High heat-transfer films  105  are formed between substrate  101   a  and p-type thermoelectric material layer  102   p  and between substrate  101   a  and n-type thermoelectric material layer  102   n , respectively. 
     Contact hole  103   a  that pierces through p-type thermoelectric material layer  102   p , n-type thermoelectric material layer  102   n , and substrate  101   a  is made in one end portion in the Y-direction of substrate  101   a . Contact hole  103   b  that pierces through substrate  101   b  is made in the other end portion in the Y-direction of substrate  101   b.    
     Conductive material  104   a  is disposed in contact hole  103   a . Conductive material  104   a  includes the projection only at one end on the side of n-type thermoelectric material layer  102   n . The projection is in contact with the surface of substrate  101   b.    
     Conductive material  104   b  is disposed in contact hole  103   b . Conductive material  104   b  includes the projections that are projected from the surfaces of substrate  101   b  at both ends in the X-direction. The projection is in contact with p-type thermoelectric material layer  102   p  at one end in the X-direction, and is in contact with n-type thermoelectric material layer  102   n  at the other end in the X-direction. 
     The gaps each having an interval which is the same length as the projected length of the projection are formed between substrate  101   b  and p-type thermoelectric material layer  102   p  and between substrate  101   b  and n-type thermoelectric material layer  102   n , respectively. The projection of conductive material  104   a  in contact hole  103   a  acts as a spacer. The projection of conductive material  104   b  in contact hole  103   b  acts as the spacer and an electric contact of p-type thermoelectric material layer  102   p  and n-type thermoelectric material layer  102   n , between which substrate  101   b  is sandwiched in the X-direction. 
     A method for producing thermoelectric conversion element  400  of Embodiment 4 will be described below with reference to  FIGS. 7A to 7D . 
     A metal mask (not illustrated) is placed over polyimide substrate  101   a , and segments of high heat-transfer film  105  are formed into a predetermined shape on both surfaces of substrate  101   a  by the sputtering, respectively ( FIG. 7A ). 
     Segments of P-type thermoelectric material  102   p  are formed on high heat-transfer film  105 , which is formed on one of two surfaces of substrate  101   a , into the substantially same shape as high heat-transfer film  105  by the sputtering, and segments of n-type thermoelectric material  102   n  are formed on high heat-transfer film  105 , which is formed on the other surface of substrate  101   a , into the substantially same shape as high heat-transfer film  105  by the sputtering, respectively ( FIG. 7B ). 
     Then, contact hole  103   a  is made in an end portion of substrate  101   a . On the other hand, substrate  101   b  is prepared, and contact hole  103   b  is made in an end portion of substrate  101   b . Holes are made in substrates  101   a  and  101   b  by the method such as the processing by the laser and the drill, the punching, and the etching, thereby making contact holes  103   a  and  103   b . Conductive material  104   a  that includes the projection at one end in the X-direction is disposed in contact hole  103   a . Conductive material  104   b  that includes the projections at both ends in the X-direction is disposed in contact hole  103   b  ( FIG. 7C ). 
     For example, conductive material  104   a  is formed by the following method. Contact hole  103   a  is sufficiently filled with the conductive paste. The end face on the side of p-type thermoelectric material layer  102   p  is formed so as to be flush with the surface of p-type thermoelectric material layer  102   p . The end face on the side of n-type thermoelectric material layer  102   n  is formed so as to be projected from the surface of n-type thermoelectric material layer  102   n  by a desired length. Therefore, conductive material  103   a  that includes the projection at the end on the side of n-type thermoelectric material layer  102   n  is formed. 
     Similarly, conductive material  104   b  is formed by the following method. Contact hole  103   b  is sufficiently filled with the conductive paste. Both ends of the conductive paste with which the contact hole  103   b  is filled are formed so as to be projected from the surfaces of substrate  101   b  by desired lengths. Therefore, conductive material  104   b  that includes the projections in both surfaces of substrate  101   b  is formed. 
     Then substrates  101   a  in each of which thermoelectric material  102  is formed and substrates  101   b  in each of which thermoelectric material  102  is not formed are alternately disposed in the X-direction ( FIG. 7D ). In this case, substrates  101   a  and substrates  101   b  are alternately disposed such that contact hole  103   a  of substrate  101   a  is disposed on one end side in the Y-direction, and such that contact hole  103   b  of substrate  101   b  is disposed on the other end side in the Y-direction. Therefore, p-type thermoelectric material layers  102   p  and n-type thermoelectric material layers  102   n  are alternately disposed with substrate  101   a  or substrate  101   b  interposed therebetween. Each of segments of P-type thermoelectric material layer  102   p  and each of segments of n-type thermoelectric material layer  102   n  are electrically connected in the X-direction, and are alternately connected at one end portion and the other end portion in the Y-direction. The gaps are formed between p-type thermoelectric conversion element  102   p  and substrate  101   b  and between n-type thermoelectric material layer  102   n  and substrate  101   b  by the projections of conductive materials  104   a  and  104   b.    
     The thermoelectric conversion element of Embodiment 4 has the same effect as that of Embodiments 1 to 3 in the same configuration as that of Embodiments 1 to 3. In the thermoelectric conversion element of Embodiment 4: substrate  101   a ; p-type thermoelectric material layer  102   p ; n-type thermoelectric material layer  102   n ; and conductive material  104   a  that electrically connects the thermoelectric material layers; are integrally formed. Therefore, compared with Embodiment 2, Embodiment 4 is more effective from the viewpoint of enhancing reliability of the electric connection. 
     In the thermoelectric conversion element of Embodiment 4, conductive material  104   a  includes the projection at one end in the X-direction, and the projection is in contact with substrate  101   b . Therefore, on one side in the X-direction, the gap between substrate  101   a  and substrate  101   b  is retained by the two projections. Accordingly, from the viewpoint of maintaining the disposed state having the gap, Embodiment 4 is more effective compared with an embodiment in which the gap is retained by the one projection. 
     This application is based on and claims the benefit of priority from the Japanese Patent Application No. 2011-035648, filed on Feb. 22, 2011, the entire contents of which are incorporated herein by reference. 
     INDUSTRIAL APPLICABILITY 
     In the thermoelectric conversion element of the invention and the producing method thereof, the number of thermoelectric material chip pairs per unit area can be increased, and the chip is hardly broken. 
     REFERENCE SIGNS LIST 
     
         
           100 ,  200 ,  300 ,  400  Thermoelectric conversion element 
           101 ,  101 ′,  101   p ,  101   n ,  101   a ,  101   b ,  803  Substrate 
           102   p ,  102   p ′ P-type thermoelectric material layer 
           102   n ,  102   n ′ N-type thermoelectric material layer 
           103   a ,  103   b ,  103   p ,  103   n  Contact hole 
           104   a ,  104   b ,  104   p ,  104   n  Conductive material 
           105  High heat-transfer film 
           301  Electrode wiring 
           601  Thermoelectric material wafer 
           602  Solder bump 
           603  Thermoelectric material chip 
           801  Current introduction terminal (positive electrode) 
           802  Current introduction terminal (negative electrode) 
           804  P-type thermoelectric material 
           805  N-type thermoelectric material 
           806  Junction electrode 
         H Arrow indicating heat flow direction
The invention provides a thermoelectric conversion element having a lot of pn junction pairs per unit area and having a thermoelectric material chip which is hardly broken, and a producing method thereof. In the thermoelectric conversion element of the invention, plural substrates in each of which a film-shaped thermoelectric material is formed in a surface thereof are disposed. As a result, because the number of pn junction pairs per unit area is increased, a high output can be obtained. Because the thermoelectric material is formed into the film shape, reliability degradation caused by a breakage of the thermoelectric material can be prevented, even in the thermoelectric material having many pn junction pairs per unit area, namely, a sectional area is small.