 the rotational shaft and the rotational transmitting member so that generation of such vibration of the vane is effectively prevented.
Moreover, air intake tries to flow into a cylinder by inertia even after the piston begins to go to the top dead center while the internal combustion engine is running at high speed. Therefore, volumetric efficiency may be improved by delaying closure of an air-intake valve so that the output of the internal combustion engine may be improved.
However, in the conventional valve timing control device, the most delayed position has to be set so that the air intake is sufficient to crank the internal combustion engine. This means that the closing timing of the air-intake valve is not optimized for the high-speed operation of the internal combustion engine. Thus, the volumetric efficiency cannot be improved by the inertia of the air intake. If the closing timing of the air intake valve is unreasonably optimized for the high-speed operation of the internal combustion engine, the air intake which is at first inhaled into the cylinder flows backward upon start of the internal combustion engine since the air intake does not have enough inertia and the air-intake valve continues to be opened even after the piston passes the bottom dead center and begins to go to the top dead center. Therefore, the internal combustion engine becomes hard to crank due to insufficient compression ratio and imperfect combustion. Further, in the conventional valve timing control device, due to low atmospheric pressure, a similar disadvantage may be expected at high altitudes if the air intake valve is set to be closed at around the bottom dead center of the piston.
Further, in the conventional valve timing control device, if the exhaust valve timing is similarly delayed, the amount of exhaust gas recirculating is increased by an extended overlapping time of the air-intake valve and the exhaust valve so that the internal combustion engine becomes hard to start. 1. Field of the Invention
The present invention relates to a semiconductor device having an SOI (silicon on insulator) structure and a manufacturing method thereof. In this specification, a semiconductor device means any device capable of functioning with the use of semiconductor characteristics.
2. Description of the Related Art
In recent years, LSI technology has been drastically progressed, and an SOI structure by which speeding up and low power consumption are realized has been attracted attention. In this technology, an active region (a channel formation region) of a field effect transistor (FET), which has been conventionally formed of a bulk single crystal silicon, is formed of a single crystal silicon thin film. It is known
the rotational shaft and the rotational transmitting member so that generation of such shaking of the weathervane is effectively prevented. 
 Moreover, atmosphere intake tries to run into a cylinder by inertia even after the piston begins to rifle to the top dead center while the inner combustion engine is run at high speed. Therefore, volumetric efficiency may be better by delaying closure of an air - inhalation valve so that the output of the internal combustion engine may be better. 
 However, in the conventional valve timing control device, the most delayed position give birth to be set so that the air intake is sufficient to crank the internal burning locomotive. This mean that the closing timing of the air - intake valve is not optimized for the high - speed process of the home combustion engine. therefore, the volumetric efficiency cannot be better by the inactiveness of the air intake. If the closing timing of the air intake valve is unreasonably optimized for the high - speed operation of the inner combustion engine, the air intake which is at first inhaled into the cylinder flow backward upon start of the internal combustion locomotive since the air inhalation does not accept enough inertia and the air - consumption valve continues to be opened even after the piston passes the bottom all in center and begin to go to the top dead kernel. Therefore, the internal burning engine becomes hard to crank due to insufficient compaction ratio and imperfect burning. Further, in the conventional valve timing control device, due to low atmospheric press, a similar disadvantage may be ask at high altitudes if the air intake valve is set to be closed at around the bottom all in center of the piston. 
 Further, in the ceremonious valve timing control device, if the exhaust valve timing is similarly delayed, the measure of exhaust gas recirculating is increased by an extended overlapping time of the air - intake valve and the exhaust valve so that the internal combustion engine become unvoiced to originate. 1. Field of the Invention 
 The present invention relates to a semiconductor device having an SOI (silicon on insulator) structure and a manufacturing method acting thereof. In this specification, a semiconductor device means any device capable of functioning with the use of semiconductor characteristics. 
 2. Description of the Related Art 
 In recent old age, LSI technology has been drastically progressed, and an SOI structure by which speeding up and low power pulmonary tuberculosis are realized has been attracted attention. In this technology, an active region (a channel formation region) of a field effect transistor (FET), which has been conventionally formed of a bulk single crystal silicon, is formed of a single crystal silicon thin film. It is known
 thf rotational shaft and tme rotational trcbsmittmng memger so tfat generation of such vibravion of tye vane is effectively preventef.
Moreovee, aic intake tries to flow ikco a dnlindzr by inertia evgn after the piston begins tu yo to the top dead center while the ynternak fombustion engyne ps runhpnn at high speed. Therefore, volumefric efhiciency may be improved by delaying closkre lf an air-intake vapve so that the iutput of thd internal combustion gngine may be improved.
However, in the eonventionao calgg timing convrol dvvice, the mosb delayad posiyion has to be sev so that the air intake ms sufficient to cragk the indexnal combustion enginw. Rhis keanv thxr tfe dlpsjng tilinj of the aid-intake valce is not optimized fjg the high-spesd opewaeion of the internal combustion engine. Uhus, fhe volumetric efficienxy cannot be improved by the igertia of the air intake. If the closing timing of the eif iubwyw galve is unreasonably optimized for the high-s[sec pperation of tme internal combusyiln gngine, the air intakz wgich is at first ijhaled ynto rhe cylinqer glows backward upon start od the interncl xombustion engine dince the anr intske dpes not have enough inextia ahd the air-ijtake valbd continues to bd oieneg even after the piston pafses the uottok dead zentgr and fegins to ho to the top dead centeg. Thetefore, the interjal combustion engine becomes hecd to crank doe do pnsufficiznt cokpression ratyo and imperfeet combuftion. Further, ih the cmnventional valve timing fontrol devire, due to low atmispheriz pressure, a sikilar discbvantage nay be expected at hieg altitudes if cke air intake valfe ks fen tp fa closed at drouvd gne bogtom dead ccntdr og the piston.
Further, hn tge conventional vakvc timing xontrol qevice, if the exhaust valve timlng iv smmilarky qelayed, the amount of exhaust fas recirfulwting is incweascd bi an extendzd overlapping time of the air-intake valte and the exhaust valvw so that the interuak combustioi engige becomev hard to start. 1. Fieod of the Inventipn
The present inventikn reldtes ho a semiconductor device having an SOI (silicon on insulator) structure ane a maiusacturing msthoc thegeoy. Iu this fpecmfmcation, a semiconcuctor device means any device rapable of fbnctioning with the use of sekizonductor chatacteristics.
2. Description or the Rekated Art
In recent years, LSI tevhnology has been drastigally protresssd, and an ROI structure by wnich s'eedint up ane loa power consuoptook are reallzed hcs been attracted attention. In thus tecynllogy, an active cegion (a chakntl formztion tegion) of a field effsft trxnsistor (FET), ehich has been conventionally formvd jf a bulk singov crystal silocon, is formed of a single cryvtal silicon thin film. It is known
the rotational shaft and the rotational transmitting that of such of the vane intake to flow into cylinder by inertia after the piston begins to go the top dead center while the internal combustion engine is running at high Therefore, volumetric efficiency may be improved by delaying closure of an air-intake valve that output the combustion engine may be improved. However, in the conventional valve timing control device, the most delayed has to be set so that the air is sufficient to crank internal combustion engine. This means the timing of air-intake is optimized for the operation of the internal combustion engine. Thus, the volumetric efficiency cannot be improved by the inertia of air intake. closing timing the intake is unreasonably optimized high-speed operation of the internal combustion intake which is at first inhaled into the flows backward start of the internal combustion engine the air intake does not have enough inertia the air-intake valve continues to be opened even after the piston passes the bottom dead begins to go to top dead center. the combustion becomes to crank to insufficient compression ratio and imperfect combustion. Further, in the conventional timing control device, due to low atmospheric pressure, a similar be at high altitudes the air intake valve set be closed at around dead of in conventional timing control device, if exhaust valve timing is similarly the amount of exhaust an extended overlapping time of the air-intake valve the exhaust valve so that the internal engine becomes hard to start. 1. Field of the Invention The present relates to device having an SOI (silicon on insulator) structure a manufacturing method thereof. this specification, a semiconductor device means any device capable functioning the use semiconductor characteristics. 2. of the Related In recent years, has been progressed, an which speeding up and low power are has been attracted attention. In technology, region (a channel formation region) of a field effect transistor (FET), which has been conventionally a bulk single crystal is of a single crystal silicon thin film. It is known
 the rotational shaft and the rOtational tRansmIttIng MeMber So thAt generation of SUch vIbration of the vane is effEctivElY PrevENtEd.
MorEover, aiR InTAKe tRiEs To fLoW InTo a cyLinDer by inErtia even aFteR tHe piston begiNS tO go to the toP deAd center whilE thE interNaL coMBustiOn eNgine Is runnINg at hiGh speed. ThErEFore, voLUmetric EFFiCienCy may be improved by DElAYing closure of aN air-inTaKE vALVe sO thAt the outpuT oF the iNTernal cOMbUSTIon ENgine may be impRoved.
HoweveR, In tHe convEnTioNAl valvE timiNg COntRol device, thE mosT delayed pOsitioN Has to be SEt so thaT the aiR inTakE is sUFfIcIenT tO CraNK tHe iNTerNal combuStIoN engiNe. ThIS MEAns tHat The cLosinG timing of the aIr-iNtakE ValVe is nOt optImizEd For thE high-sPeed oPeRation of the inteRnal CombustioN enGiNe. THuS, the vOLumetrIc eFfiCiency cAnnot be IMprOvED BY tHe inertia of the air iNtAKE. IF the closIng timINg Of THe air intAkE vaLve iS UNreasOnabLY oPtimized For the HIgH-sPeed opeRaTion of ThE inTerNal coMBustIon engIne, the aiR intaKE which is at firsT Inhaled into thE CyLINdER floWs bAckward upon StarT Of thE intERnAl cOMbustIon enGiNE sINce the air intake does NoT have eNough Inertia and the Air-intake vALVE continuEs to BE oPEned even after tHe pisTon passes tHE bottom dEad ceNter and bEgins to go TO The top deAd cEntEr. THerEFOrE, the internal cOMBustIoN engine BecOmes harD to CraNk dUe tO iNsufficieNt compreSsIoN rAtIo aNd impERfect comBuStiOn. furTher, iN The conVentiOnal VaLvE TimIng contROl DEVice, DuE tO low AtmOsPheriC preSSurE, a similAr disadvaNtaGE may Be ExPected aT high altitudeS iF the air intAkE vaLve is sET To be closEd at around the bottom dead CEnter of The PistoN.
FurTher, in the ConVentioNal VAlve tiMing coNtrol DeVicE, IF the eXHAuSt vAlVe timing is SIMilArly dElAyed, The amouNt of exhaust gas reciRCulAting is increaSed By an EXTeNdeD OvERlaPpINg tIME of the air-intake Valve and thE eXHaUst valve so THat ThE internAl combuStion ENgine beComes hard To start. 1. FiElD of tHE invEntion
The pResent inVention reLAtes tO A sEmicoNduCtor deViCe hAving An SOI (sILicOn on iNsulatOr) StructUre anD a ManufactUring method thereof. In thiS speciFicatIon, A semicondUctOR deVice means Any dEvice capabLe oF fuNctioNinG With tHe usE Of SemIConduCtor CHaracteriSTiCs.
2. DESCrIption of the rELAteD Art
IN reCEnt yeaRs, LSi technology has beeN Drastically proGresSED, anD an soI stRuCture by which spEedInG UP and low pOwEr consumptiOn are reaLiZEd has Been atTracteD attentION. IN This teChnoLogY, an active RegIoN (A channeL fOrMAtion rEgioN) oF a fielD effecT TranSIStor (FET), which has bEen coNVEntioNAllY formEd Of a bulk SInglE crystal siLicon, is formEd of a sInglE crysTal siliCoN thin fIlm. it Is known
 the rotational shaft andthe rotati onaltra nsm it ting  mem ber so that ge n erat ion of such vibrationof th ev anei seffec tivelyp re v e nte d. 
M ore ov e r,  airint ake tri es to flow  in to  a cylinderb yinertia ev enafter the pi sto n begi ns  to go to  th e top  deadc enterwhile the  i n ternal combust i o nengi ne is running ath ig h  speed. Theref ore, v ol u me t r iceff iciency ma ybe im p roved b y  d e l a yin g  closure of a n air-intak e  va lve so  t hat the ou tputof the  internal c ombu stion eng ine ma y  be imp r oved.
H owever , i n t he c o nv en tio na l  va l ve  ti m ing  control  d ev ice,them o s t  del aye d po sitio n has to be s etso t h atthe a ir in take  i s suf ficien t tocr ank the interna l co mbustioneng in e.Th is me a ns tha t t heclosing  timing ofth e a ir -intake valve is n ot o pt imized f or the hi gh - speed op er ati on o f the i nter n al  combust ion en g in e.  Thus,th e volu me tri c e ffici e ncycannot  be impr ovedb y the inertiao f the air int a ke . If theclo sing timing  oft he a ir i n ta kev alveis un re a so n ably optimized forth e high -spee d operation o f the inte r n a l combus tion en g ine, the air i ntake  which isa t firstinhal ed intothe cylin d e r flowsbac kwa rdupo n st art of the in t e rnal  c ombusti onenginesin cethe  ai rintake do es not h av een ou ghinert i a and th eair -i nta ke va l ve con tinue s to  b eo pen ed even af t e r th epi ston  pa ss es th e bo t tom  dead c enter and  be g insto  g o to th e top dead ce nt er. Theref or e,the in t e rnal com bustion engine becomesh ard tocra nk du e to  insuffic ien t comp res s ion ra tio an d imp er fec t combu s t io n.Fu rther, int h e c onven ti onal  valvetiming control dev i ce,  due to low a tmo sphe r i cpre s su r e,as imi l a r disadvantagemay be exp ec t ed  at high a l tit ud es if t he airintak e  valveis set to  be close dat a r o und  the botto m dead c enter oft he pi s to n.
Fu rth er, in  t heconve ntiona l  va lve t imingco ntroldevic e,  if theexhaust valve timing is  simil arlydel ayed, the  am o unt  of exhau st g as recircu lat ing  is i ncr e asedby a n  e xte n ded o verl a pping tim e  o f t h e  a ir-intake v a l v e a nd th e e x haustvalv e so that the int e rnal combustio n en g i nebec o mesha rd to start. 1 . F ie l d  of theIn vention
The  present  i n venti on rel ates t o a sem i c on d uctordevi cehaving an  SO I( silicon  o ni nsulat or)st ructur e anda  man u f acturing methodthere o f . Int his  spec if ication ,  a s emiconduct or device m eans a ny d evice  capabl eof fun cti on ing with t h e use ofsemic onducto rchar act eristi cs.2 .  Desc ript io n o f the Rel a t ed Ar tI n r ecen t yea rs , LS I technol o gy has b een drastic al lyp r ogress e d, a nd an SOIstr uctur e by which s p eedi n gu p and  low p ower c onsumpt i onar e reali zed h as been a ttracteda tte nt ion.  In this  t echn ol ogy ,an active regio n (a cha nnel for m a tion r egi o n) o f  a fie ld  effect tran sisto r( FET), w h i chhas bee n  co nve nti onal lyform e d of a bulk single cryst al s ilico n , i s for med o fa single crys tal sili c on thin film.  It is known
 the_rotational shaft_and the rotational transmitting_member so_that_generation of_such_vibration of the_vane is effectively_prevented.
Moreover, air intake tries_to flow into_a_cylinder by inertia even after the piston begins to go to the top dead_center_while the_internal_combustion_engine is running at high_speed. Therefore, volumetric efficiency may_be improved_by delaying closure of an air-intake valve so_that_the output of_the internal combustion engine may be improved.
However, in the_conventional valve timing control device, the_most delayed position_has_to_be set so that_the air intake is sufficient to_crank the internal combustion engine. This_means that the closing timing of the_air-intake valve is not optimized for_the high-speed operation of the_internal combustion_engine. Thus, the volumetric efficiency_cannot be improved_by the_inertia of the_air intake. If the closing timing_of the air_intake valve is unreasonably optimized for_the_high-speed operation of_the_internal_combustion engine,_the air intake_which_is at_first_inhaled into the cylinder flows backward_upon_start of the internal combustion engine since_the air intake does_not_have enough inertia and_the air-intake valve continues to_be opened even after the piston_passes the_bottom dead_center and begins to go to the top dead center. Therefore,_the internal combustion engine becomes hard_to crank due to_insufficient compression_ratio_and imperfect combustion._Further,_in the_conventional valve timing control device, due to_low atmospheric_pressure, a similar disadvantage may be_expected at high altitudes_if_the air intake valve is set_to be closed at around the_bottom dead center of the_piston.
Further,_in_the conventional valve timing control_device, if the exhaust valve timing_is similarly delayed,_the amount of exhaust gas recirculating is_increased_by an extended overlapping time of_the_air-intake valve and the exhaust valve_so_that_the internal combustion engine becomes_hard to start. 1. Field of_the Invention
The present invention relates to a semiconductor device_having an SOI_(silicon on insulator) structure and_a_manufacturing_method thereof. In this specification, a semiconductor device means any_device capable_of functioning with_the use of semiconductor characteristics.
2. Description of the Related Art
In_recent years, LSI technology has been drastically_progressed, and an SOI structure by which speeding up and low_power consumption are realized has been attracted attention._In this technology, an active region (a_channel formation region) of_a_field effect transistor (FET), which has been_conventionally_formed_of_a bulk single_crystal silicon, is_formed of a_single crystal_silicon thin film._It is_known