CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of application Ser. No. 09/797,368, filed Mar. 1, 2001, pending, which is a continuation of application Ser. No. 09/097,427, filed Jun. 15, 1998, now U.S. Pat. 6,240,535 B1, issued May 29, 2001, which is a continuation-in-part of Ser. No. 08/718,173, filed Sep. 19, 1996, now U.S. Pat. No. 5,796,746, issued Aug. 18, 1998, which is a continuation-in-part of application Ser. No. 08/577,840, filed Dec. 22, 1995, now U.S. Pat. No. 5,825,697, issued Oct. 20, 1998, and Ser. No. 08/666,247, filed Jun. 20, 1996, now U.S. Pat. No. 5,764,574, issued Jun. 9, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Technical Field  
           [0003]    This invention relates in general to integrated circuit (IC) dice and, in particular, to devices and methods for testing dice in IC modules.  
           [0004]    2. State of the Art  
           [0005]    Integrated circuit (IC) dice are typically tested before they are packaged to determine if they have any failing circuitry. In general, one of the first steps in testing a die is to initiate a test mode in the die by applying control signals to selected bond pads on the die referred to as test bond pads. As an example, most Dynamic Random Access Memory (DRAM) dice manufactured by the Assignee of this invention, Micron Technology, Inc. of Boise, Id., are tested in a test mode initiated, in part, by applying a logic &#39; 7  0&#39; 8  signal to their Output Enable (OE) bond pad.  
           [0006]    As shown in FIG. 1, when multiple dice  10  are packaged together in an IC module  12 , their test bond pads  14  (e.g., their OE bond pads) are often interconnected with their reference voltage bond pads  16  to the reference voltage V SS  through module terminals  18  to ensure that a test mode cannot be accidentally initiated in an end user&#39;s system., While this works well to prevent accidental initiation of a test mode in dice in an IC module in the field, unfortunately it also prevents intentional testing of the dice by an IC manufacturer after they are packaged in the IC module.  
           [0007]    One conventional solution to this problem, described in U.S. Pat. Nos. 5,278,839 and 4,519,078, is to eliminate the need to initiate a test mode in the manner described above by incorporating self test circuitry into dice. Because the self test circuitry is controlled through address and control bond pads that generally are not fixed to the reference voltage V SS  or supply voltage V CC , a test mode can be initiated with the self test circuitry after the dice are packaged in an IC module. However, self test circuitry is a cumbersome and expensive solution that does not address the need for a solution that is easily incorporated into existing dice and IC modules.  
           [0008]    Because it would be advantageous to have the flexibility to test dice after they are packaged in an IC module, there is a need in the art for an improved device and method for initiating and performing such testing.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    An inventive integrated circuit (IC) module, such as a Multi-Chip Module (MCM), includes a terminal receiving a test mode initiate signal, such as a supply voltage V CC , and an IC die having a bond pad and a function circuit. A switching apparatus, such as a fuse, is connected with the bond pad between the terminal and the function circuit to conduct the test mode initiate signal to the function circuit, and an impedance apparatus, such as a resistor, connected between the function circuit and an operational mode signal, such as a reference voltage V SS , supports a difference in voltages between the test mode initiate signal at the function circuit and the operation mode signal. The function circuit responds to the test mode initiate signal by initiating a test mode in the die. The switching circuit also selectively isolates the function circuit from the die, and the impedance apparatus then conducts the operational mode signal to the function circuit. The function circuit responds to the operational mode signal by entering an operational mode. Thus, a test mode can be initiated in the die after it is packaged in the IC module by providing the test mode initiate signal at the terminal, and the test mode can then be disabled and the die fixed in the operational mode by selectively isolating the function circuit from the terminal with the switching apparatus, thereby ensuring that the test mode is not accidentally initiated by an end user in the field.  
           [0010]    In one version of this inventive IC module, the switching apparatus and the impedance apparatus are both incorporated in the die, and in other versions one or both of the switching apparatus and impedance apparatus are incorporated in a substrate of the IC module. In another version, the IC module itself is incorporated into an electronic system, such as a computer system. In still other versions, the operational mode signal is provided by an operational mode signal circuit on the die, or is provided by external circuitry through another terminal in the IC module. Finally, in a modified version of this inventive IC module, the test mode initiate signal is generated on the die by a test mode initiate signal circuit responsive to external circuitry rather than being provided by external circuitry.  
           [0011]    In another embodiment of this invention, an IC module includes one or more terminals receiving a test mode initiate signal and an operational mode signal. One or more IC dice in the IC module each have one or more function circuits and a plurality of bond pads, and a first subset of the bond pads is coupled to the function circuits while a second subset of the bond pads is adapted to receive signals other than the test mode initiate signal in the test mode. A dedicated conduction circuit coupled between the terminals and the first subset bond pads and isolated from the second subset bond pads conducts the test mode initiate and operational mode signals to the function circuits. When the function circuits receive the test mode initiate signal, they initiate a test mode, and when the function circuits receive the operational mode signal, they enter an operational mode. Thus, a test mode can be initiated in the dice after they are packaged in the IC module by providing the test mode initiate signal at the terminals, and an operational mode can be initiated by providing the operational mode signal at the terminals. In one version of this IC module, the IC module is incorporated into an electronic system. In other versions, the terminals comprise a first terminal receiving the test mode initiate signal and a second terminal receiving the operational mode signal, and the first and second terminals are coupled by an impedance element, such as a resistor, or by a link, such as a surface mount resistor or a jumper.  
           [0012]    In a further embodiment of this invention, a method for initiating a test mode and an operational mode in dice in an IC module includes: receiving a test mode initiate signal at a terminal of the IC module; conducting the test mode initiate signal only to those bond pads on dice in the IC module adapted to receive the signal and from those bond pads to function circuits in the dice to initiate a test mode therein; discontinuing conduction of the test mode initiate signal to the function circuits; and conducting an operational mode initiate signal to each function circuit to initiate the operational mode therein.  
           [0013]    In a still further embodiment, a method for testing one or more dice in an IC module includes: providing a test mode initiate signal to an externally accessible terminal of the IC module; conducting the test mode initiate signal exclusively to bond pads on the dice adapted to receive the signal to initiate a test mode in the dice; testing each die; receiving response signals from the dice; and evaluating the response signals to identify any failing elements in the dice. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is an isometric view of a conventional integrated circuit module;  
         [0015]    [0015]FIG. 2 is an isometric, block and schematic view of an integrated circuit module including a switching circuit and an impedance circuit in accordance with this invention;  
         [0016]    FIGS.  3 A-C are schematic views of alternative versions of the switching circuit of FIG. 2;  
         [0017]    FIGS.  4 A-C are schematic views of alternative versions of the impedance circuit of FIG. 2;  
         [0018]    [0018]FIG. 5 is a schematic and block view of an alternative version of the switching and impedance circuits of FIG. 2;  
         [0019]    [0019]FIG. 6A is a block diagram of an electronic system in accordance with this invention;  
         [0020]    [0020]FIG. 6B is a block diagram and circuit schematic of a switching circuit of the electronic system of FIG. 6A;  
         [0021]    [0021]FIG. 7 is an isometric and schematic view of another integrated circuit module in accordance with this invention;  
         [0022]    [0022]FIGS. 8A and 8B are isometric and schematic views of alternative versions of the integrated circuit module of FIG. 7;  
         [0023]    [0023]FIG. 9 is a block diagram of an integrated circuit die in accordance with this invention;  
         [0024]    [0024]FIG. 10 is a block, schematic and isometric view of a test apparatus in accordance with this invention;  
         [0025]    [0025]FIG. 11 is a block diagram of an alternative version of the test apparatus of FIG. 10;  
         [0026]    [0026]FIGS. 12A and 12B are flow diagrams of a method for testing integrated circuit dice in an integrated circuit module in accordance with this invention; and  
         [0027]    [0027]FIGS. 13A and 13B are flow diagrams showing the method of FIGS. 12A and 12B in more detail. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    As shown in FIG. 2, an inventive integrated circuit (IC) module  20  includes IC dice  22  having function circuits, such as input buffers  24 , selectively receiving a test mode initiate signal, such as a supply voltage V cc , through a module terminal  26 , a switching circuit  28 , and test mode enable bond pads  30  (e.g., Output Enable (OE) bond pads). It will be understood by those having skill in the field of this invention that the IC module  20  may be any electronic structure having at least one die accessed externally through terminals, including, for example, any Multi-Chip Module (MCM), such as a Single In-line Memory Module (SIMM), a Dual In-line Memory Module (DIMM), a Random Access Memory (RAM) card, a flash Read-Only-Memory (ROM) module or card, a Synchronous Dynamic RAM (SDRAM) module or card, and a Rambus RAM module or card. It will also be understood that the dice  22  may be any dice for purposes of this invention, including, for example, DRAM dice, Static Random Access Memory (SRAM) dice, Synchronous Graphics Random Access Memory (SGRAM) dice, ROM dice, and processor dice.  
         [0029]    Also, it will be understood that the function circuits may be any circuitry on a die for initiating a test mode in the die, the test mode initiate signal may be any signal for initiating a test mode in a die, the module terminal  26  may be any terminal including, for example, an MCM pin (e.g., a SIMM, DIMM, RAM card, RAM module, ROM card, or ROM module pin), the switching circuit  28  may be, for example, a fuse or a transistor or any other device for selectively isolating the function circuits from the module terminal  26 , and the test mode enable bond pads  30  may be any bond pads connectable to a function circuit for enabling a test mode in a die. Further, it should be understood that although the switching circuit  28  is shown in FIG. 2 as being a single circuit coupled to the module terminal  26 , it may instead comprise a plurality of circuits, each one coupled to the module terminal  26  and one of the dice  22 .  
         [0030]    In response to receiving the test mode initiate signal, the input buffers  24  initiate a test mode in the dice  22 . In this mode, various test signals may be provided to the dice  22  in a well known manner to test the circuitry thereon, and the dice  22  then output various response signals indicating the presence of any failing circuitry. While the test mode initiate signal, such as the supply voltage V CC , is being provided to the test mode enable bond pads  30  and the input buffers  24 , an impedance circuit  32 , such as, for example, a resistor, resistance-connected MOS transistor, or anti-fuse, supports a difference in voltages between the test mode initiate signal at the test mode enable bond pads  30  and an operational mode enable signal, such as a reference voltage V SS , at a reference terminal  34 , such as, for example, an MCM pin (e.g., a SIMM, DIMM, RAM card, RAM module, ROM card, or ROM module pin). It will be understood that although the impedance circuit  32  is shown in FIG. 2 as being a single circuit coupled to the reference terminal  34 , it may instead comprise a plurality of circuits, each one coupled to the reference terminal  34  and one of the dice  22 .  
         [0031]    Once testing of the dice  22  is complete, the switching circuit  28  isolates the input buffers  24  from the module terminal  26  to disable the test mode, and the impedance circuit  32  conducts the operational mode signal, such as the reference voltage V SS , to the input buffers  24 . In response, the input buffers  24  initiate an operational mode in the dice  22  in which the dice  22  operate in accordance with their intended normal function. Thus, for example, if the dice  22  are DRAMs, they would perform normal memory operations in their operational mode.  
         [0032]    Thus, the dice  22  in the IC module  20  are fully testable even after being packaged, and yet their test mode can be disabled as necessary so the IC module  20  can be used by end users in the field.  
         [0033]    As will be described in more detail below with respect to FIGS. 6 and 9, one or both of the switching circuit  28  and the impedance circuit  32  may be incorporated into the dice  22  instead of being provided on a substrate  36  of the IC module  20  as shown in FIG. 2. Also, as will be described in more detail below with respect to FIG. 9, one or both of the test mode initiate signal and the operational mode signal may be generated on the dice  22  rather than being provided by external circuitry.  
         [0034]    As shown in FIGS. 3A, 3B, and  3 C, the switching circuit  28  of FIG. 2 can be, for example, a fuse  38  that is blown once testing is complete, or an NMOS transistor  40  or PMOS transistor  42  that is de-activated once testing is complete. Also, as shown in FIGS. 4A, 4B and  4 C, the impedance circuit  32  of FIG. 2 can be, for example, a resistor  44 , an anti-fuse  46  that is blown once testing is complete, or an NMOS transistor  48  that is activated once testing is complete. Further, as shown in FIG. 5, the NMOS transistor  40  of FIG. 3B and the NMOS transistor  48  of FIG. 4C, for example, may be controlled by an anti-fuse isolate logic circuit  50  that outputs a high voltage during a test mode and is then programmed to output a low voltage once testing is complete. The high voltage during the test mode activates the NMOS transistor  40  and de-activates the NMOS transistor  48  through an inverter  52 , and the low voltage after programming de-activates the NMOS transistor  40  and activates the NMOS transistor  48  through the inverter  52 . Of course, a wide variety of other combinations are well within the scope of this invention.  
         [0035]    As shown in FIG. 6A, in another embodiment this invention comprises an electronic system  60 , such as a computer system, including an input device  62 , an output device  64 , a processor device  66 , such as a state machine, and a memory device, such as an IC module  68 . Although this embodiment will be described with respect to the memory device comprising the IC module  68 , it will be understood that the IC module  68  could comprise all or any portion of the input device  62 , the output device  64 , the processor device  66 , and the memory device. Also, although the electronic system  60  will be described with respect to a particular IC module  68 , it will be understood that this invention includes any of the inventive IC modules described herein as incorporated into an electronic system. Further, as discussed above, it will be understood that the IC module  68  may comprise any electronic structure having at least one die externally accessible through terminals, including, for example, an MCM, such as a SIMM, DIMM, RAM card, RAM module, ROM card, or ROM module.  
         [0036]    The IC module  68  includes a terminal  70 , such as an MCM pin as discussed above, receiving a test mode initiate signal (e.g., the supply voltage V CC ) from the processor device  66 . The terminal  70  conducts the test mode initiate signal to a bond pad  72  of an IC die  74 . As discussed above, it will be understood that the IC die  74  may be any die, including, for example, a DRAM die, SRAM die, SGRAM die, processor die, flash ROM die, SDRAM die, or Rambus RAM die.  
         [0037]    To initiate a test mode in the die  74 , a switching circuit  76  conducts the test mode initiate signal from the bond pad  72  to a function circuit  78  (e.g., an OE input buffer). In response, the function circuit  78  initiates a test mode in the die  74  as described above. While the test mode initiate signal is being conducted to the function circuit  78 , an impedance circuit  80  supports a difference in voltages between the test mode initiate signal at the function circuit  78  and an operational mode signal, such as a reference voltage V SS , supplied by an operational mode voltage circuit  82 .  
         [0038]    It should be understood that the switching circuit  76  may, for example, comprise a fuse, a MOS transistor, or a flash memory cell, the function circuit  78  may comprise any circuit which enables or initiates a test mode in response to a test mode initiate signal, the impedance circuit  80  may, for example, comprise an anti-fuse, a MOS transistor, or a resistor, and the operational mode voltage circuit  82  may comprise any circuit for supplying an operational mode signal, such as a reference voltage V SS , on a die.  
         [0039]    When testing is over, the switching circuit  76  isolates the function circuit  78  from the bond pad  72  to disable the test mode in the die  74  by, for example, blowing a fuse or de-activating a MOS transistor. The impedance circuit  80  then conducts the operational mode signal from the operational mode voltage circuit  82  to the function circuit  78  by, for example, blowing an anti-fuse or activating a MOS transistor. In response to the operational mode signal, the function circuit  78  initiates an operational mode in the die  74  as described above.  
         [0040]    Thus, the die  74  is fully testable even after being packaged in the IC module  68 , and yet the test mode of the die  74  can be disabled as necessary so the IC module  68  can be used by end users in the field.  
         [0041]    As shown in detail in FIG. 6B, the switching circuit  76  of FIG. 6A may include a flash memory cell  77  programmed to activate or deactivate an NMOS transistor  79 . The cell  77  may be programmed, for example, to conduct the test mode initiate signal during a test mode, and to isolate the bond pad  72  (FIG. 6A) from the function circuit  78  (FIG. 6A) during normal operations of the electronic system  60  (FIG. 6A).  
         [0042]    As shown in FIG. 7, an inventive IC module  84  includes dice  86  having function circuits, such as input buffers  88 , selectively receiving a test mode initiate signal, such as a supply voltage V cc , through a first terminal  90 , a dedicated conductor  92 , and test mode enable bond pads  94  (e.g., Output Enable (OE) bond pads). It will be understood by those having skill in the field of this invention that the IC module  84  may be any electronic structure having at least one die accessed externally through terminals, including, for example, an MCM, such as a SIMM, a DIMM, a RAM card, a RAM module, a ROM card, and a ROM module. It will also be understood that the dice  86  may be any dice for purposes of this invention, including, for example, DRAM dice, SRAM dice, SGRAM dice, flash ROM dice, SDRAM dice, Rambus RAM dice, and processor dice.  
         [0043]    Also, it will be understood that the function circuits may be any circuitry on a die for initiating a test mode in the die, the test mode initiate signal may be any signal for initiating a test mode in a die, the first terminal  90  may be any terminal including, for example, an MCM pin, such as a SIMM, DIMM, RAM card, ROM card, RAM module, or ROM module pin, the dedicated conductor  92  may be, for example, any conductive structure or device connected exclusively to those bond pads  94  on the dice  86  adapted to receive the test mode initiate signal or unaffected by receipt of the test mode initiate signal, and the test mode enable bond pads  94  may be any bond pads connectable to a function circuit for enabling a test mode in a die.  
         [0044]    In response to receiving the test mode initiate signal, the input buffers  88  initiate a test mode in the dice  86  in a well known manner as described above. Once testing of the dice  86  is complete, an operational mode signal, such as a reference voltage V SS , is provided through the first terminal  90  and the dedicated conductor  92  to the input buffers  88  to initiate an operational mode in the dice  86  in the well known manner described above. A second terminal  96  provides the reference voltage V SS  to other circuits in the dice  86  via a reference conductor  97  and reference voltage bond pads  98 .  
         [0045]    Thus, the dice  86  in the IC module  84  are fully testable even after being packaged, and yet the operational mode can be enabled as necessary so the IC module  84  can be used by end users in the field.  
         [0046]    As shown in FIG. 8A in an isometric view of a portion of an alternative version of the IC module  84  of FIG. 7, a conductive via  100  through a substrate  102  of the IC module  84  couples the first terminal  90  and dedicated conductor  92  to the second terminal  96  and the reference conductor  97  through an impedance element, such as a surface mount resistor  104 . Of course, the impedance element may, for example, comprise a resistance-connected MOS transistor rather than the surface mount resistor  104 .  
         [0047]    During testing, a test mode initiate signal, such as the supply voltage V CC , may be supplied to the first terminal  90  to initiate a test mode as described above with respect to FIG. 7. At the same time, an operational mode signal, such as the reference voltage V SS , may be supplied to the second terminal  96  without interfering with the test mode, because the surface mount resistor  104  supports a difference in voltages between the test mode initiate signal at the first terminal  90  and the operational mode signal at the second terminal  96 .  
         [0048]    Once testing is complete, the operational mode signal, or no signal, may be supplied to the first terminal  90 . At the same time, the surface mount resistor  104  conducts the operational mode signal from the second terminal  96  to the dedicated conductor  92 , in order to initiate the operational mode as described above with respect to FIG. 7.  
         [0049]    As shown in FIG. 8B in an isometric view of a portion of another alternative version of the IC module  84  of FIG. 7, a test mode initiate signal, such as the supply voltage V cc , may be supplied to the first terminal  90  during testing to initiate a test mode as described above with respect to FIG. 7. At the same time, an operational mode signal, such as the reference voltage V ss , may be supplied to the second terminal  96  and the reference conductor  97  without interfering with the test mode, because a removable link  106 , such as a jumper or zero Ohm surface mount resistor, is not present during testing, thus isolating the second terminal  96  from the first terminal  90 .  
         [0050]    Once testing is complete, the operational mode signal, or no signal, may be supplied to the first terminal  90 . At the same time, the link  106  is positioned to connect the second terminal to the dedicated conductor  92  through the conductive via  100  in the substrate  102 , thereby conducting the operational mode signal from the second terminal  96  to the dedicated conductor  92  in order to initiate the operational mode as described above with respect to FIG. 7.  
         [0051]    Although the first and second terminals  90  and  96  are shown in FIGS. 8A and 8B as being on opposing sides of the substrate  102 , it will be understood that the invention is not so limited.  
         [0052]    As shown in FIG. 9, in another embodiment, this invention comprises an IC die  108 . As discussed above, the IC die  108  may be any die including, for example, a DRAM die, SRAM die, SGRAM die, flash ROM die, SDRAM die, Rambus RAM die, or processor die. To initiate a test mode in the die  108 , a test mode enable signal directs a test mode voltage circuit  110  in the die  108  to generate a test mode voltage V TEST , such as 3.3 Volts. A switching circuit  112  then conducts the test mode voltage V TEST  to a function circuit  114  (e.g., an OE input buffer). In response, the function circuit  114  initiates a test mode in the die  108  as described above. While the test mode voltage V TEST  is being conducted to the function circuit  114 , an impedance circuit  116  supports a difference in voltages between the test mode voltage V TEST  at the function circuit  114  and an operational mode voltage V OPER , such as 0.0 Volts, supplied by an operational mode voltage circuit  118 .  
         [0053]    It should be understood that the switching circuit  112  may, for example, comprise a fuse or a MOS transistor, the function circuit  114  may comprise any circuit which enables or initiates a test mode in response to a test mode voltage V TEST , the impedance circuit  116  may, for example, comprise an anti-fuse, a MOS transistor, or a resistor, and the operational mode voltage circuit  118  may comprise any circuit for supplying an operational mode voltage V OPER  on a die.  
         [0054]    When testing is over, the switching circuit  112  isolates the function circuit  114  from the test mode voltage V TEST  to disable the test mode in the die  108  by, for example, blowing a fuse or de-activating a MOS transistor. The impedance circuit  116  then conducts the operational mode voltage V OPER  from the operational mode voltage circuit  118  to the function circuit  114  by, for example, blowing an anti-fuse or activating a MOS transistor. In response to the operational mode voltage V OPER , the function circuit  118  initiates an operational mode in the die  108  as described above.  
         [0055]    Thus, the die  108  is fully testable even after being packaged, and yet the test mode of the die  108  can be disabled as necessary so the die  108  can be used by end users in the field.  
         [0056]    As shown in FIG. 10, a test apparatus  120  for testing an IC module  122  of this invention having an IC die  124  includes a test-apparatus-to-module interface  126  having interface terminals  128  connectable to module terminals  130  on the IC module  122 . The module terminals  130 , in turn, are in communication with the die  124  including a redundancy circuit  132 . A test mode enable circuit  134  provides a test mode initiate signal to the die  124  through the interface  126  to initiate a test mode in the die  124  in the manner described above. A test signal circuit  136  then provides test signals to the die  124  through the interface  126  to test the die  124  in the test mode. A response signal circuit  138  receives response signals from the die  124  in the test mode in response to the test signals, and an evaluator circuit  140  then evaluates the response signals to identify any failing circuitry in the die  124 .  
         [0057]    A repair enablement device  142  in the test apparatus  120  may provide repair control signals to the redundancy circuit  132  in the die  124  directing the redundancy circuit  132  to replace any failing circuitry identified by the evaluator circuit  140  with redundant elements  144  in the die  124 . The manner in which repair control signals may direct the redundancy circuit  132  to repair any failing circuitry in the die  124  is well known by those skilled in the art.  
         [0058]    As shown in FIG. 11 in a block diagram of an alternative version of the test apparatus  120  described with respect to FIG. 10, a processor  146  coupled to a memory device  148  and an input/output device  150  may provide the test mode initiate signal, the test signals, and the repair control signals, and may receive and evaluate the response signals, in the manner described above with respect to FIG. 10. It should be understood that the memory device  148  may comprise any permanent or temporary electronic storage medium, including, for example, a DRAM, SRAM, SGRAM, disk, tape, memory card, memory module, or programmable logic array.  
         [0059]    As shown in still another embodiment of this invention in FIGS. 12A and 12B, a method for testing any one of the above-described inventive IC dice or modules includes the steps of:  160  providing a test mode initiate signal to an externally accessible terminal of an IC module;  162  conducting the test mode initiate signal exclusively to bond pads on dice in the IC module adapted to receive the signal to initiate a test mode in the dice;  164  testing each of the dice in the test mode by providing test signals to each die through the externally accessible terminals of the IC module;  166  receiving response signals from each die through the terminals of the IC module in response to the test signals;  168  evaluating the response signals from each die to identify any failing elements in the dice of the IC module;  170  providing repair control signals to a redundant circuit in each die to direct each die to replace any identified failing elements with redundant elements;  172  re-testing each die by providing re-test signals to each die through the IC module&#39;s externally accessible terminals;  174  receiving response signals from each die through the IC module&#39;s terminals in response to the re-test signals; and  176  evaluating the response signals from each die to confirm the repair of any failing elements therein.  
         [0060]    As shown in FIGS. 13A and 13B, the step  170  from FIGS. 12A and 12B of providing repair control signals to a redundant circuit in each die includes, for each identified failing element, the steps of:  180  determining an address associated with the failing element;  182  latching the failing element&#39;s address into the dice;  184  providing a programming mode enable signal, such as a super voltage Column Address Strobe (CAS) signal, to the dice to enable a programming mode therein;  186  applying a fuse address of a fusebank enable anti-fuse associated with a redundant element selected to replace the failing element to the IC module&#39;s terminals to identify the location of the anti-fuse;  188  coupling to the anti-fuse;  190  determining the anti-fuse&#39;s resistance;  192  applying a programming voltage, such as a voltage between 8 and 10 Volts, to the anti-fuse to blow the anti-fuse;  194  redetermining the anti-fuse&#39;s resistance to confirm it is blown; and, for each asserted address bit in each failing element&#39;s address:  198  applying a fuse address of an address bit anti-fuse associated with the redundant element selected to replace the failing element to the IC module&#39;s terminals to identify the location of the anti-fuse;  200  coupling to the anti-fuse;  202  determining the address bit anti-fuse&#39;s resistance;  204  applying a programming voltage, such as a voltage between 8 and 10 Volts, to the anti-fuse to blow the anti-fuse; and  206  redetermining the address bit anti-fuse&#39;s resistance to confirm it is programmed. As used herein, each &#39; 7  asserted&#39; 8  address bit in a failing element&#39;s address may be each &#39; 7  1&#39; 8  bit in the address or each &#39; 7  0&#39; 8  bit in the address.  
         [0061]    It will be understood that any or all of the steps  160 - 206  in the embodiment of FIGS. 12A, 12B,  13 A, and  13 B, or any portion thereof, may be implemented in hardware, software, or both, using a wide variety of well-known architectures, including, for example, a state machine and the embodiment of FIGS. 10 and 11. It will also be understood that, although the embodiment of FIGS. 12A, 12B,  13 A, and  13 B has been described with respect to anti-fuses, any programmable circuit or element will work for purposes of this invention. Also, it will be understood that the step  186  in FIG. 13A may include automatic selection of the location and type of redundant element (e.g., redundant row or column) to be used to replace the failing element. Finally, it will be understood that the steps  180  to  206  of FIGS. 13A and 133B may be automated by computer or performed manually.  
         [0062]    This invention thus advantageously provides a device and method for testing and repairing IC dice already packaged in IC modules.  
         [0063]    Although this invention has been described with reference to particular embodiments, the invention is not limited to these described embodiments. Rather, the invention is limited only by the appended claims, which include within their scope all equivalent devices and methods that operate according to the principles of the invention as described.
An IC module, such as a Multi-Chip Module (MCM), includes multiple IC dice, each having a test mode enable bond pad, such as an output enable pad. A fuse incorporated into the MCM's substrate connects each die's test mode enable bond pad to one of the MCM's no-connection (N/C) pins, and a resistor incorporated into the substrate connects the test mode enable bond pads to one of the MCM's ground pins. By applying a supply voltage to the test mode enable bond pads through the N/C pin, a test mode is initiated in the dice. Once testing is complete, the fuse may be blown, and a ground voltage applied to the test mode enable bond pads through the ground pins so the resistor disables the test mode in the dice and initiates an operational mode. As a result, dice packaged in IC modules may be tested after packaging. A method for performing such testing once the test mode has been initiated and for repairing any failing elements found during testing includes providing test signals to the dice, receiving response signals from the dice, evaluating the response signals to identify any failing elements in the dice, programming the failing elements' addresses into anti-fuses in the dice with a programming voltage, confirming that the addresses are programmed by determining the resistance of the anti-fuses, re-testing the dice, receiving response signals from the re-tested dice, and evaluating the response signals to confirm all repairs.