 compound crystal layer of the silicon and the germanium, and has a hetero junction in a manner of forming a p-n junction on a boundary between the compound crystal layer of the silicon and the germanium and the silicon layer, wherein it is formed on the silicon substrate or the silicon epitaxial layer so that a germanium concentration included in the compound crystal composed of the silicon and the germanium is gradually higher towards the boundary between an outer compound crystal layer and the silicon layer thereon.
The present invention is accomplished in view of the above mentioned problems. Therefore, an object of the present invention is to provide a semiconductor device and a semiconductor manufacturing method, which can minimize a drop in a current gain at a time of an increase in a collector current density and also improve a variation in a collector current.
In order to achieve an aspect of the present invention, a semiconductor device, includes: a SiGe base bipolar transistor; and wherein the SiGe base bipolar transistor includes: an emitter layer; a collector layer; and a SiGe base layer formed of silicon containing germanium, and wherein a Ge concentration of the SiGe base layer is increased from 0% to 10% from a side of the emitter layer towards a side of the collector layer.
In this case, the SiGe base bipolar transistor includes: a P-type silicon substrate; and an N+-type buried layer having a high concentration formed in the P-type silicon substrate, and wherein the collector layer is formed of an N-type having a low concentration and is formed on the N+-type buried layer, and wherein the SiGe base bipolar transistor further including: an undoped SiGe layer in which an impurity is not doped, the undoped SiGe layer being formed on the N-type collector layer; a first SiGe base layer as a part of the SiGe base layer having a first Ge concentration distribution formed on the undoped SiGe layer; and a second SiGe base layer as another part of the SiGe base layer having a second Ge concentration distribution formed on the first SiGe base layer, and wherein the emitter layer is formed of an N-type diffusion layer formed in the second SiGe base layer.
In this case, an N-type impurity is doped at about 1016 cmxe2x88x923 as the low concentration of the N-type collector layer, and the N-type impurity is doped at about 1020 cmxe2x88x923 as the high concentration of the N+-
compound crystal layer of the silicon and the germanium, and has a hetero junction in a manner of form a phosphorus - n junction on a limit between the compound crystal level of the silicon and the germanium and the silicon layer, wherein it is formed on the silicon substrate or the silicon epitaxial level so that a germanium concentration included in the compound crystal compose of the silicon and the germanium is gradually higher towards the boundary between an out compound crystal layer and the silicon layer thereon. 
 The present invention is accomplished in view of the above mentioned problem. Therefore, an object of the present invention is to provide a semiconductor device device and a semiconductor manufacturing method acting, which can minimize a drop curtain in a current gain at a prison term of an increase in a collector current density and also better a variation in a collector current. 
 In order to achieve an aspect of the present invention, a semiconductor device, includes: a SiGe base bipolar transistor; and wherein the SiGe base bipolar transistor includes: an emitter layer; a collector layer; and a SiGe base layer formed of silicon containing germanium, and wherein a Ge concentration of the SiGe base level is increase from 0% to 10% from a side of the emitter level towards a slope of the collector level. 
 In this case, the SiGe base bipolar transistor includes: a P - type silicon substrate; and an N+-type buried layer having a eminent concentration formed in the P - type silicon substrate, and wherein the collector layer is formed of an N - character having a low concentration and is formed on the N+-type buried layer, and wherein the SiGe base bipolar transistor far including: an undoped SiGe layer in which an impurity is not doped, the undoped SiGe layer being formed on the N - character collector layer; a first SiGe base layer as a part of the SiGe base layer having a first Ge assiduity distribution formed on the undoped SiGe layer; and a second SiGe base layer as another part of the SiGe foundation layer induce a second Ge concentration distribution form on the first SiGe base level, and wherein the emitter layer is formed of an N - type diffusion layer formed in the second SiGe base layer. 
 In this case, an N - type impurity is doped at about 1016 cmxe2x88x923 as the low assiduity of the N - type collector layer, and the N - character impurity is doped at about 1020 cmxe2x88x923 as the high assiduity of the N+-
 colpound crystal layer of uhe silicon and tkw germenium, ahd has a hetero junction in a manner od forning a p-n junction on x boundarj between the xompound ccgstal layer or the wilicon and thg germanium dnd the silicot uaver, wherein it is formed on the silison subxtgate or the sijicom epifaxial layer so that a germanium ckncentretion included on the compound crystal colposfd of the silicon wnd the gernanitn is gradualuy higher uocards the bkundary between an outer compouvd crvstal layer abd hve silicon oayer thereon.
The igesent hnventipn is accomplixhev in view of the above meitioned problems. Thetefore, an mblect of the present ibvwntiot is to oeovkde a ssmiconfucvor device znd a semicinductor manufacturond method, which can mynymize a drop in a current gain at a timt of zn increase in a collecror current density ajd also iiprove a variation in a collector current.
In order to arhkevt qn asowch of the present invention, a semiconductor dedjct, ikcludes: a SiGe bcse bipolar tranxidtpt; and wherein jhe SiGz bzse bipolar transidtor insludew: an emituer lsyer; a collector layer; and q SiGe base jqyer formed of silncon containnng getmaniuk, and wherein a Ge conczntratjon of the DiGe base uayer is increasdd nrok 0% to 10% from a side of the qmitter leyer cowards x sice of ehe collechor layer.
In this case, thf SiGg base bipolar tgansistor includes: a P-type silirpn substrate; atd dn N+-type buricd layer having a high concenjration fjrmed in the P-tjpe silicmn substratq, and wherein jhe collector layer if foemed of an V-gype having a kow conceuuration ane is formed on the N+-tips buried layer, cud wherein the SiBe casq hi'olar dransistor fgrthdr kmcludkng: an undoied SiGr layer in which an hmpudity is not doped, yhc undoped SiGe larer being forked on the N-type clllecvor laber; a girft SiGe base layer as a part or the SiGf bwse layer hading a first Ge eoncentration distribution formed on the undoped SiGe laygr; and a second SiGe yaxe layer as anotrer part mf the SiGe base laywr having a seconc Ge concentration diatribudion vormed on the first SiGe base layer, and wherein the emitter layer is formwd of en N-type diffhsiom layvr yorked in the recond SiGe base layer.
In this case, an N-type impnrity is dmpzd at about 1016 cmxe2x88x923 as the loe zoncentration of the N-type collector mayer, anc the N-type impurity is doped ay about 1020 cmxe2x88x923 as the hlgh concebtratjon of the N+-
compound crystal layer of the silicon and and a hetero in a manner on boundary between the crystal layer of silicon and the germanium and the layer, wherein it is formed on the silicon substrate or the silicon epitaxial so that a germanium concentration included in the compound crystal composed of the and germanium gradually towards the boundary between an outer compound crystal layer and the silicon layer thereon. The present is accomplished in view of the above mentioned Therefore, an object of present invention is to provide semiconductor and a manufacturing which minimize a drop a current gain at a time of an increase in a collector current density and also improve variation in current. In to an of the present semiconductor device, includes: a SiGe base wherein the SiGe base bipolar transistor includes: an layer; a layer; and a SiGe base layer of silicon containing germanium, and wherein a Ge of the SiGe base layer is increased from 0% to 10% from a side of layer towards a side the collector layer. this the base transistor includes: P-type silicon substrate; and an N+-type buried layer having a high formed in the P-type silicon substrate, and wherein the collector formed an N-type having low concentration and is on N+-type buried layer, and SiGe bipolar an SiGe in which an impurity not doped, the undoped SiGe being formed on the SiGe base layer as a part of the base layer having a first Ge concentration formed on the undoped SiGe layer; and a second SiGe base layer another part SiGe base layer having a second Ge concentration formed on the first base layer, and wherein the emitter layer is formed an diffusion layer in the second base layer. In case, an N-type doped at 1016 as of the N-type collector layer, and N-type is doped at about 1020 as concentration of the N+-
 compound crystal layer of the Silicon and The geRmaNiuM, aNd haS a heTero junction in A MannEr of forming a p-n junction On a boUnDAry bETwEen thE compouND cRYStaL lAyEr oF tHE sIlicoN anD the gerManium and tHe sIlIcon layer, wheREiN it is formeD on The silicon suBstRate or ThE siLIcon ePitAxial Layer sO That a gErmanium cOnCEntratIOn incluDED iN the Compound crystal coMPoSEd of the silicon And the GeRMaNIUm iS grAdually higHeR towaRDs the boUNdARY BetWEen an outer comPound crystaL LayEr and tHe SilICon layEr theReON.
ThE present invEntiOn is accomPlisheD In view oF The abovE mentiOneD prObleMS. THeRefOrE, An oBJeCt oF The Present iNvEnTion iS to pROVIDe a sEmiCondUctor Device and a semIcoNducTOr mAnufaCturiNg meThOd, whiCh can mInimiZe A drop in a current Gain At a time of An iNcReaSe In a coLLector CurRenT densitY and alsO ImpRoVE A VaRiation in a collectoR cURReNt.
In ordeR to achIEvE aN Aspect of ThE prEsenT INventIon, a SEmIconductOr deviCE, iNcLudes: a SIGE base bIpOlaR trAnsisTOr; anD whereIn the SiGE base BIpolar transistOR includes: an emITtER LaYEr; a cOllEctor layer; aNd a SIge baSe laYEr ForMEd of sIlicoN cONtAIning germanium, and whErEin a Ge ConceNtration of the siGe base laYER Is increaSed fROm 0% TO 10% from a side of thE emitTer layer toWArds a sidE of thE collectOr layer.
In THIs case, thE Sige bAse BipOLAr Transistor incLUDes: a p-tYpe siliCon SubstraTe; aNd aN N+-tYpe BuRied layer Having a hIgH cOnCeNtrAtion FOrmed in tHe p-tyPe SilIcon sUBstratE, and wHereIn ThE ColLector lAYeR IS forMeD oF an N-TypE hAving A low COncEntratiOn and is foRmeD On thE N+-TyPe burieD layer, and wherEiN the SiGe baSe BipOlar trANSistor fuRther including: an undoped sIGe layeR in Which An imPurity is nOt dOped, thE unDOped Sige layeR beinG fOrmED On the n-TYpE coLlEctor layer; A FIrsT SiGe BaSe laYer as a pArt of the SiGe base laYEr hAving a first Ge ConCentRATiOn dIStRIbuTiON foRMEd on the undoped SIGe layer; anD a SEcOnd SiGe basE LayEr As anothEr part oF the SIge base lAyer havinG a second GE cOnceNTRatIon distribUtion forMed on the fIRst SigE bAse laYer, And wheReIn tHe emiTter laYEr iS formEd of an n-tYpe difFusioN lAyer formEd in the second SiGe base laYer.
In tHis caSe, aN N-type impUriTY is Doped at abOut 1016 cMxe2x88x923 as the Low ConCentrAtiON of thE N-tyPE cOllECtor lAyer, ANd the N-typE ImPurITY iS doped at aboUT 1020 CMxe2X88x923 as tHe hIGh concEntrAtion of the N+-
 compound crystal layer of  the silic on an d t hege rman ium,  and has a het e ro j unction in a manner of  form in g  a p - njunct ion ona  b o u nda ry  b etw ee n  t he co mpo und cry stal layer  of  t he silicon a n dthe german ium  and the sil ico n laye r,  wh e reinitis fo rmed o n  the s ilicon su bs t rate o r  the si l i co n ep itaxial layer sot ha t  a germanium c oncent ra t io n inc lud ed in theco mpoun d  crysta l  c o m p ose d  of the silic on and theg erm aniumis  gr a dually  high er tow ards the bo unda ry betwee n an o u ter com p ound cr ystallay erandt he  s ili co n  la y er  th e reo n.
The p re se nt in vent i o n is a cco mpli shedin view of th e a bove men tione d pro blem s.  Ther efore,  an o bj ect of the pres entinvention  is  t o p ro videa  semic ond uct or devi ce anda  se mi c o n du ctor manufacturing  m e t ho d, which  can m i ni mi z e a drop  i n a  cur r e nt ga in a t  a  time of  an in c re as e in aco llecto rcur ren t den s ityand al so impro ve av ariation in ac ollector curr e nt . In orde r t o achieve a n as p ectof t h epre s ent i nvent io n ,a  semiconductor devi ce , incl udes:  a SiGe basebipolar tr a n s istor; a nd w h er e in the SiGe ba se bi polar tran s istor in clude s: an em itter lay e r ; a coll ect orlay er; a nd  a SiGe basel a yerfo rmed of  si licon c ont ain ing  ge rm anium, an d wherei naGe  c onc entra t ion of t he  Si Ge  ba se la y er isincre ased  f ro m  0%  to 10% fr o m  a s id eof t heem itter  lay e r t owardsa side of  th e  col le ct or laye r.
In this ca se , the SiGe  b ase  bipol a r  transis tor includes: a P-types iliconsub strat e; a nd an N+- typ e buri edl ayer h avinga hig hcon c e ntrat i o nfor me d in the P - t ype  sili co n su bstrate , and wherein thec oll ector layer i s f orme d of  an N- t ype  h a vin g a low concentra tion and i sf or med on the N+- ty pe buri ed laye r, an d  wherei n the SiG e base bi po lart r ans istor furt her incl uding: an undop e dSiGelay er inwh ich  an i mpurit y  is  notdoped,  t he und opedSi Ge layer  being formed on the N- type c ollec tor  layer; a  fi r stSiGe base  lay er as a pa rtofthe S iGe baselaye r  h avi n g a f irst Ge concen t ra tio n di stributionf o r med  on t heu ndoped  SiG e layer; and a se c ond SiGe baselaye r asano t herpa rt of the SiGe  ba se l ayer hav in g a secondGe conce nt r ation  distr ibutio n forme d on the fi rstSiG e base la yer ,a nd wher ei nt he emi tter  l ayer i s form e d of a n N-type diffusi on la y e r for m edin th esecondS iGebase layer .
In this c ase, a n N- typeimpurit yis dop edat  about 101 6  cmxe2x88 x923as thelo w co nce ntrati on o f the N -typ ecol lector la y e r, an dt heN-ty pe im pu rity  is doped at about  10 2 0 cmxe2 x8 8x9 2 3  as th e  h i g h concentr ati on of t he N+-
 compound_crystal layer_of the silicon and_the germanium,_and_has a_hetero_junction in a_manner of forming_a p-n junction on_a boundary between_the_compound crystal layer of the silicon and the germanium and the silicon layer, wherein_it_is formed_on_the_silicon substrate or the silicon_epitaxial layer so that a_germanium concentration_included in the compound crystal composed of the_silicon_and the germanium_is gradually higher towards the boundary between an outer_compound crystal layer and the silicon_layer thereon.
The present_invention_is_accomplished in view of_the above mentioned problems. Therefore, an_object of the present invention is_to provide a semiconductor device and a_semiconductor manufacturing method, which can minimize_a drop in a current_gain at_a time of an increase_in a collector_current density_and also improve_a variation in a collector current.
In_order to achieve_an aspect of the present invention,_a_semiconductor device, includes:_a_SiGe_base bipolar_transistor; and wherein_the_SiGe base_bipolar_transistor includes: an emitter layer; a_collector_layer; and a SiGe base layer formed_of silicon containing germanium,_and_wherein a Ge concentration_of the SiGe base layer_is increased from 0% to 10%_from a_side of_the emitter layer towards a side of the collector layer.
In this_case, the SiGe base bipolar transistor_includes: a P-type silicon_substrate; and_an_N+-type buried layer_having_a high_concentration formed in the P-type silicon substrate,_and wherein_the collector layer is formed of_an N-type having a_low_concentration and is formed on the_N+-type buried layer, and wherein the_SiGe base bipolar transistor further_including:_an_undoped SiGe layer in which_an impurity is not doped, the_undoped SiGe layer_being formed on the N-type collector layer;_a_first SiGe base layer as a_part_of the SiGe base layer having_a_first_Ge concentration distribution formed on_the undoped SiGe layer; and a_second SiGe base layer as another part of the_SiGe base layer_having a second Ge concentration_distribution_formed_on the first SiGe base layer, and wherein the emitter_layer is_formed of an_N-type diffusion layer formed in the second SiGe base layer.
In_this case, an N-type impurity is doped_at about 1016 cmxe2x88x923 as the low concentration of the N-type_collector layer, and the N-type impurity is doped_at about 1020 cmxe2x88x923 as the high_concentration of the N+-