WO2005065144B1 - Planarization method of manufacturing a superjunction device - Google Patents

Planarization method of manufacturing a superjunction device

Info

Publication number
WO2005065144B1
WO2005065144B1 PCT/US2004/041375 US2004041375W WO2005065144B1 WO 2005065144 B1 WO2005065144 B1 WO 2005065144B1 US 2004041375 W US2004041375 W US 2004041375W WO 2005065144 B1 WO2005065144 B1 WO 2005065144B1
Authority
WO
WIPO (PCT)
Prior art keywords
doped region
conductivity type
mesa
trenches
main surface
Prior art date
Application number
PCT/US2004/041375
Other languages
French (fr)
Other versions
WO2005065144A3 (en
WO2005065144A2 (en
Filing date
Publication date
Application filed filed Critical
Priority to JP2006545758A priority Critical patent/JP4417962B2/en
Priority to EP04813671A priority patent/EP1706899A4/en
Publication of WO2005065144A2 publication Critical patent/WO2005065144A2/en
Publication of WO2005065144A3 publication Critical patent/WO2005065144A3/en
Publication of WO2005065144B1 publication Critical patent/WO2005065144B1/en

Links

Abstract

A method of manufacturing a semiconductor device includes providing a substrate having first and second main surfaces. The substrate has a heavily doped region of a first conductivity at the second main surface and has a lightly doped region of the first conductivity at the first main surface. The method includes providing trenches and mesas in the substrate, implanting, at an angle, a dopant of the first conductivity into a sidewall of a mesa and implanting, at an angle, a dopant of a second conductivity into the mesa at another sidewall. The method includes oxidizing the sidewalls and bottoms of each trench and tops of the mesas to create a top oxide layer, etching back the top oxide layer to expose a portion of the mesa, depositing an oxide layer to cover the etched back top layer and mesa and planarizing the top surface of the device.

Claims

AMENDED CLAIMS received by the International Bureau on 27 January 2006 (27.01.2006)I claim:
1. A method of manufacturing a semiconductor device comprising;
providing a semiconductor substrate having first and second main surfaces opposite to each other, the semiconductor substrate having a heavily doped region of a first conductivity type at the second main surface and having a lightly doped region of the first conductivity type at the first main surface;
forming in the semiconductor substrate a plurality of trenches and a plurality of mesas, each of the plurality of trenches having a first extending portion extending from the first main surface toward the heavily doped region to a first depth position, each of the plurality of trenches being disposed between adjacent mesas, each of the plurality of mesas having sidewall surfaces;
implanting a dopant of the first conductivity type into a preselected mesa region of the semiconductor substrate at a sidewall surface of one mesa so as to form at the sidewall surface of the at least one mesa a first doped region of the first conductivity type having a doping concentration lower than that of the heavily doped region;
implanting a dopant of the second conductivity type into the preselected mesa region at a sidewall surface opposite to the sidewall implanted with the dopant of the first conductivity type, to provide a second doped region of the second conductivity type at the sidewall surface opposite to the sidewall implanted with the dopant of the first conductivity type;
oxidizing the sidewalls and bottoms of at least the trenches adjacent to the preselected mesa region and the top of the preselected mesa region to create a top oxide layer;
etching back the top oxide layer to expose a preselected portion of the preselected mesa; depositing an oxide layer using a process selected from a group that includes tetraethylorthosilicate (TEOS) and spun-on-glass (SOG) oxide deposition to cover the etched back top layer and preselected mesa; and
planarizing the top surface of the device.
2. The method according to claim 1 , further comprising:
providing a third doped region of the second conductivity type at the first main surface of the first and second doped regions to be electrically connected to the second doped region;
providing a fourth doped region of the first conductivity type at at least one of the first main surface and a sidewall surface of the one tronch such that the fourth doped region is opposite to the first doped region with the third doped region posed therebetween; and
providing a gate electrode layer opposite to the third doped τegion between the first and fourth doped regions, with a gate insulation layer interposed therebetween.
3. The method according to claim 2, wherein the gate electrode layer is formed on the first main surface.
4. The method according to claim 1 , further comprising:
providing a third doped region of the second conductivity type at the first main surface of the first and second doped regions to be electrically connected to the second doped region.
5. The method according to claim 1 , wherein a diffusion length of each of the dopants of the fast and second conductivity types in manufacturing the semiconductor device is longer than a distance from the sidewall surfaces of the adjacent pair of trenches to the P-N junction of the first and second doped regions.
6. A method of manufacturing a semiconductor device comprising:
providing a semiconductor substrate having first and second main surfaces opposite to each other, the semiconductor substrate having Λ heavily doped region of a first conductivity type at the second main surface and having a lightly doped region of the first conductivity type at the first main surface;
forming in the semiconductor substrate a plurality of trenches and a plurality of mesa regions, each of the plurality of mesa regions having a first extending portion extending from the first main surface toward the heavily doped region to a first depth position and having a sidewall surface, each of the plurality of mesa regions being surrounded by one of the plurality of trenches;
implanting a dopant of the first conductivity type into a preselected group of mesa regions of the plurality of mesa regions at a sidewall surface in one of the plurality of trenches to form at the sidewall surface of each of the preselected group of mesa regions a first doped region of the first conductivity type having a doping concentration lower than that of the heavily doped region;
implanting a dopant of a second conductivity type into the preselected group of mesa regions at a sidewall surface opposite to the sidewall implanted with the dopant of the first conductivity type to provide a second doped region of the second conductivity type at the sidewall surtace opposite to the sidewall implanted with the dopant of the first conductivity type; oxidizing at least the bottom of each of the trenches adjacent to the preselected group of mesa regions and sidewalls and the tops of the preselected group of mesa regions to create a top oxide layer,
etching back the top oxide layer to expose a preselected portion of the preselected group of mesa regions;
depositing an oxide layer using a process selected from a group that includes tetraethylorthosilicate (TEOS) and spun-on-glass (SOG) o>ide deposition to cover the etched back top layer and preselected mesa; and
planarizmg the top surface of the device.
7. The method according to claim 6, further comprising:
providing a third doped region of the second conductivity type at the first main surface of the first and second doped regions to be electrically connected to the second doped region;
providing a fourth doped region of the first conductivity type at one of the first main surface and a sidewall surface of the one trench such that the fourth doped region is opposite to the first doped region with the third doped region posed therebetween; and
providing a gate electrode layer opposite to the third doped region between the first and fourth doped regions, with a gate insulation layer interposed therebetween.
8. The method according to claim 6, wherein the gate electrode layer is armed on the first main surface.
9. The method according to claim 6, further comprising: providing a third doped region of the second conductivity type at the first main surface of the first and second doped τegions to be electrically connected to the second doped region.
10. The method according to claim 6, further comprising:
providing an electrode layer in ohmic contact with the first doped region.
11. The method according to claim 6, wherein a diffusion length of each of the dopants of the fast and second conductivity types in manufacturing the semiconductor device is longer than a distance from the sidewall surfaces of the adjacent pair of trenches to a P-N junction of the first and second doped regions.
12. The method according to claim 1 , wherein each of the plurality of trenches has an approximate equal width relative to the other trenches.
13. The method according to claim 1 , wherein each of the sidewall surfaces has a predetermined inclination angle maintained relative to the first main surface.
14. The method according to claim 1, wherein the implanting of the dopant of the first conductivity type is performed at a first predetermined angle of implant.
15. The method according to claim 1 , wherein the implanting of the dopant of the second conductivity type is performed at a second predetermined angle of implant.
16. The method according to claim 6, wherein each of the plurality of trenches has an approximate equal width relative to the other trenches.
17. The method according to claim 6, wherein each of the sidewall surfaces has a predetermined inclination angle maintained relative to the first main surface.
18. The method according to claim 6, wherein the implanting of the dopant of the first conductivity type is performed at a first predetermined angle of implant.
19. The method according to claim 6, wherein the implanting of the dopant of the second conductivity type is performed at a second predetermined angle of implant.
20. A semiconductor device comprising:
a semiconductor substrate having first and second main surfaces opposite to each other, the semiconductor substrate having a heavily doped region of a first conductivity type at the second main surface and having a lightly doped region of the first conductivity type at the first main surface,
the first main surface including a plurality of trenches and a plurality of mesas, each of the plurality of trenches having a first extending portion extending from the first main surface toward the heavily doped region to a first depth position, each of the plurality of trenches being disposed between adjacent mesas, each of the plurality of mesas having sidewall surfaces;
a first doped region of the first conductivity type having a doping concentration lower than that of the heavily doped region formed at a sidewall surface of at least one mesa; a second doped region of the second conductivity type formed at a sidewall surface opposite to the sidewaU surface having the first doped region;
a top oxide layer formed on the sidewalls and bottoms of at least the trenches adjacent to the preselected mesa region and the top of the preselected mesa region; and
a second oxide layer formed using a process selected from a group that includes tetraethylorthosilicate (TEOS) and spun-on-glass (SOQ) oxide deposition that covers at least an etched back portion of the top layer and the preselected mesa region.
PCT/US2004/041375 2003-12-19 2004-12-10 Planarization method of manufacturing a superjunction device WO2005065144A2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2006545758A JP4417962B2 (en) 2003-12-19 2004-12-10 Planarization method in the manufacture of superjunction devices
EP04813671A EP1706899A4 (en) 2003-12-19 2004-12-10 Planarization method of manufacturing a superjunction device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US53146703P 2003-12-19 2003-12-19
US60/531,467 2003-12-19

Publications (3)

Publication Number Publication Date
WO2005065144A2 WO2005065144A2 (en) 2005-07-21
WO2005065144A3 WO2005065144A3 (en) 2006-03-02
WO2005065144B1 true WO2005065144B1 (en) 2006-04-20

Family

ID=34748767

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2004/041375 WO2005065144A2 (en) 2003-12-19 2004-12-10 Planarization method of manufacturing a superjunction device

Country Status (6)

Country Link
US (1) US7199006B2 (en)
EP (1) EP1706899A4 (en)
JP (1) JP4417962B2 (en)
KR (1) KR100879588B1 (en)
TW (1) TWI353621B (en)
WO (1) WO2005065144A2 (en)

Families Citing this family (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4417962B2 (en) * 2003-12-19 2010-02-17 サード ディメンジョン (スリーディ) セミコンダクタ インコーポレイテッド Planarization method in the manufacture of superjunction devices
US7023069B2 (en) * 2003-12-19 2006-04-04 Third Dimension (3D) Semiconductor, Inc. Method for forming thick dielectric regions using etched trenches
EP1701686A4 (en) * 2003-12-19 2009-07-01 Third Dimension 3D Sc Inc Method of manufacturing a superjunction device with conventional terminations
US7439583B2 (en) * 2004-12-27 2008-10-21 Third Dimension (3D) Semiconductor, Inc. Tungsten plug drain extension
TWI401749B (en) 2004-12-27 2013-07-11 Third Dimension 3D Sc Inc Process for high voltage superjunction termination
EP1710843B1 (en) * 2005-04-04 2012-09-19 STMicroelectronics Srl Integrated power device
WO2006116219A1 (en) * 2005-04-22 2006-11-02 Icemos Technology Corporation Superjunction device having oxide lined trenches and method for manufacturing a superjunction device having oxide lined trenches
US7446018B2 (en) 2005-08-22 2008-11-04 Icemos Technology Corporation Bonded-wafer superjunction semiconductor device
US7429772B2 (en) * 2006-04-27 2008-09-30 Icemos Technology Corporation Technique for stable processing of thin/fragile substrates
US7723172B2 (en) 2007-04-23 2010-05-25 Icemos Technology Ltd. Methods for manufacturing a trench type semiconductor device having a thermally sensitive refill material
US8580651B2 (en) * 2007-04-23 2013-11-12 Icemos Technology Ltd. Methods for manufacturing a trench type semiconductor device having a thermally sensitive refill material
US8012806B2 (en) 2007-09-28 2011-09-06 Icemos Technology Ltd. Multi-directional trenching of a die in manufacturing superjunction devices
US8159039B2 (en) 2008-01-11 2012-04-17 Icemos Technology Ltd. Superjunction device having a dielectric termination and methods for manufacturing the device
US7846821B2 (en) 2008-02-13 2010-12-07 Icemos Technology Ltd. Multi-angle rotation for ion implantation of trenches in superjunction devices
US7795045B2 (en) * 2008-02-13 2010-09-14 Icemos Technology Ltd. Trench depth monitor for semiconductor manufacturing
US8030133B2 (en) 2008-03-28 2011-10-04 Icemos Technology Ltd. Method of fabricating a bonded wafer substrate for use in MEMS structures
US7807576B2 (en) * 2008-06-20 2010-10-05 Fairchild Semiconductor Corporation Structure and method for forming a thick bottom dielectric (TBD) for trench-gate devices
US20110198689A1 (en) * 2010-02-17 2011-08-18 Suku Kim Semiconductor devices containing trench mosfets with superjunctions
US9490372B2 (en) * 2011-01-21 2016-11-08 Semiconductor Components Industries, Llc Method of forming a semiconductor device termination and structure therefor
US8598654B2 (en) 2011-03-16 2013-12-03 Fairchild Semiconductor Corporation MOSFET device with thick trench bottom oxide
JP2013175655A (en) * 2012-02-27 2013-09-05 Toshiba Corp Power semiconductor device and method of manufacturing the same
US8946814B2 (en) 2012-04-05 2015-02-03 Icemos Technology Ltd. Superjunction devices having narrow surface layout of terminal structures, buried contact regions and trench gates
US9576842B2 (en) 2012-12-10 2017-02-21 Icemos Technology, Ltd. Grass removal in patterned cavity etching
US9391135B1 (en) 2015-03-23 2016-07-12 Semiconductor Components Industries, Llc Semiconductor device
CN106158955A (en) 2015-03-30 2016-11-23 中芯国际集成电路制造(上海)有限公司 Power semiconductor and forming method thereof
US9991338B2 (en) 2015-09-17 2018-06-05 Semiconductor Components Industries, Llc Electronic device including a conductive structure surrounded by an insulating structure
US10497602B2 (en) 2016-08-01 2019-12-03 Semiconductor Components Industries, Llc Process of forming an electronic device including forming an electronic component and removing a portion of a substrate
FR3061357B1 (en) * 2016-12-27 2019-05-24 Aledia METHOD FOR PRODUCING AN OPTOELECTRONIC DEVICE COMPRISING AN ENGRAVING STEP ON THE REAR SIDE OF THE GROWTH SUBSTRATE

Family Cites Families (59)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4158206A (en) 1977-02-07 1979-06-12 Rca Corporation Semiconductor device
JPS5553462A (en) 1978-10-13 1980-04-18 Int Rectifier Corp Mosfet element
US5019522A (en) 1986-03-21 1991-05-28 Advanced Power Technology, Inc. Method of making topographic pattern delineated power MOSFET with profile tailored recessed source
US5045903A (en) 1988-05-17 1991-09-03 Advanced Power Technology, Inc. Topographic pattern delineated power MOSFET with profile tailored recessed source
US4895810A (en) 1986-03-21 1990-01-23 Advanced Power Technology, Inc. Iopographic pattern delineated power mosfet with profile tailored recessed source
US5677867A (en) * 1991-06-12 1997-10-14 Hazani; Emanuel Memory with isolatable expandable bit lines
US5472888A (en) 1988-02-25 1995-12-05 International Rectifier Corporation Depletion mode power MOSFET with refractory gate and method of making same
CN1019720B (en) 1991-03-19 1992-12-30 电子科技大学 Power semiconductor device
JPH05190663A (en) * 1992-01-07 1993-07-30 Iwatsu Electric Co Ltd Manufacture of semiconductor integrated circuit
JPH05304297A (en) 1992-01-29 1993-11-16 Nec Corp Semiconductor power device and manufacture thereof
US5506421A (en) * 1992-11-24 1996-04-09 Cree Research, Inc. Power MOSFET in silicon carbide
CN1035294C (en) 1993-10-29 1997-06-25 电子科技大学 Withstand voltage layer with special shaped doped island for semiconductor device
US5435888A (en) 1993-12-06 1995-07-25 Sgs-Thomson Microelectronics, Inc. Enhanced planarization technique for an integrated circuit
US5665633A (en) * 1995-04-06 1997-09-09 Motorola, Inc. Process for forming a semiconductor device having field isolation
JP3402043B2 (en) * 1996-01-22 2003-04-28 日産自動車株式会社 Field effect transistor
WO1997029518A1 (en) 1996-02-05 1997-08-14 Siemens Aktiengesellschaft Field effect controlled semiconductor component
US5926713A (en) * 1996-04-17 1999-07-20 Advanced Micro Devices, Inc. Method for achieving global planarization by forming minimum mesas in large field areas
US5744994A (en) 1996-05-15 1998-04-28 Siliconix Incorporated Three-terminal power mosfet switch for use as synchronous rectifier or voltage clamp
KR0183886B1 (en) 1996-06-17 1999-04-15 김광호 Trench element isolation method of semiconductor device
JP3327135B2 (en) 1996-09-09 2002-09-24 日産自動車株式会社 Field effect transistor
JP3607016B2 (en) 1996-10-02 2005-01-05 株式会社半導体エネルギー研究所 Semiconductor device and manufacturing method thereof, and portable information processing terminal, head mounted display, navigation system, mobile phone, camera, and projector
JP3618517B2 (en) 1997-06-18 2005-02-09 三菱電機株式会社 Semiconductor device and manufacturing method thereof
US5976947A (en) 1997-08-18 1999-11-02 Micron Technology, Inc. Method for forming dielectric within a recess
US6239463B1 (en) 1997-08-28 2001-05-29 Siliconix Incorporated Low resistance power MOSFET or other device containing silicon-germanium layer
US6337499B1 (en) * 1997-11-03 2002-01-08 Infineon Technologies Ag Semiconductor component
US6081009A (en) 1997-11-10 2000-06-27 Intersil Corporation High voltage mosfet structure
DE19909282A1 (en) * 1998-03-06 1999-11-11 Nat Semiconductor Corp Formation of an oxide isolation structure in silicon
CN1223004C (en) * 1998-07-23 2005-10-12 三菱电机株式会社 Semiconductor device and manufacture thereof
US6291856B1 (en) 1998-11-12 2001-09-18 Fuji Electric Co., Ltd. Semiconductor device with alternating conductivity type layer and method of manufacturing the same
DE19854915C2 (en) 1998-11-27 2002-09-05 Infineon Technologies Ag MOS field effect transistor with auxiliary electrode
EP1011146B1 (en) 1998-12-09 2006-03-08 STMicroelectronics S.r.l. Method of manufacturing an integrated edge structure for high voltage semiconductor devices
US6452230B1 (en) 1998-12-23 2002-09-17 International Rectifier Corporation High voltage mosgated device with trenches to reduce on-resistance
US6190970B1 (en) 1999-01-04 2001-02-20 Industrial Technology Research Institute Method of making power MOSFET and IGBT with optimized on-resistance and breakdown voltage
US6222229B1 (en) 1999-02-18 2001-04-24 Cree, Inc. Self-aligned shield structure for realizing high frequency power MOSFET devices with improved reliability
US6198127B1 (en) 1999-05-19 2001-03-06 Intersil Corporation MOS-gated power device having extended trench and doping zone and process for forming same
EP1058303A1 (en) 1999-05-31 2000-12-06 STMicroelectronics S.r.l. Fabrication of VDMOS structure with reduced parasitic effects
JP3851744B2 (en) * 1999-06-28 2006-11-29 株式会社東芝 Manufacturing method of semiconductor device
DE19964214C2 (en) 1999-09-07 2002-01-17 Infineon Technologies Ag Method for producing a drift zone of a compensation component
GB9929613D0 (en) 1999-12-15 2000-02-09 Koninkl Philips Electronics Nv Manufacture of semiconductor material and devices using that material
US6214698B1 (en) 2000-01-11 2001-04-10 Taiwan Semiconductor Manufacturing Company Shallow trench isolation methods employing gap filling doped silicon oxide dielectric layer
US6392273B1 (en) * 2000-01-14 2002-05-21 Rockwell Science Center, Llc Trench insulated-gate bipolar transistor with improved safe-operating-area
GB0012138D0 (en) * 2000-05-20 2000-07-12 Koninkl Philips Electronics Nv A semiconductor device
US6399998B1 (en) * 2000-09-29 2002-06-04 Rockwell Technologies, Llc High voltage insulated-gate bipolar switch
US6509220B2 (en) 2000-11-27 2003-01-21 Power Integrations, Inc. Method of fabricating a high-voltage transistor
JP4088033B2 (en) 2000-11-27 2008-05-21 株式会社東芝 Semiconductor device
US6608350B2 (en) 2000-12-07 2003-08-19 International Rectifier Corporation High voltage vertical conduction superjunction semiconductor device
US6424007B1 (en) 2001-01-24 2002-07-23 Power Integrations, Inc. High-voltage transistor with buried conduction layer
US6710403B2 (en) * 2002-07-30 2004-03-23 Fairchild Semiconductor Corporation Dual trench power MOSFET
WO2002069394A1 (en) 2001-02-27 2002-09-06 Fairchild Semiconductor Corporation Process for depositing and planarizing bpsg for dense trench mosfet application
US6512267B2 (en) * 2001-04-12 2003-01-28 International Rectifier Corporation Superjunction device with self compensated trench walls
US6551881B1 (en) * 2001-10-01 2003-04-22 Koninklijke Philips Electronics N.V. Self-aligned dual-oxide umosfet device and a method of fabricating same
ITTO20011038A1 (en) * 2001-10-30 2003-04-30 St Microelectronics Srl PROCEDURE FOR THE MANUFACTURE OF AN INTEGRATED SEMICONDUCTIVE SLICE FOR ELECTRONIC DEVICES AND A STRUCTURE FOR THE DECOUPLING AND
JP3993458B2 (en) * 2002-04-17 2007-10-17 株式会社東芝 Semiconductor device
JP4928947B2 (en) * 2003-12-19 2012-05-09 サード ディメンジョン (スリーディ) セミコンダクタ インコーポレイテッド Manufacturing method of super junction device
JP4417962B2 (en) * 2003-12-19 2010-02-17 サード ディメンジョン (スリーディ) セミコンダクタ インコーポレイテッド Planarization method in the manufacture of superjunction devices
US7023069B2 (en) * 2003-12-19 2006-04-04 Third Dimension (3D) Semiconductor, Inc. Method for forming thick dielectric regions using etched trenches
TWI348219B (en) * 2003-12-19 2011-09-01 Third Dimension 3D Sc Inc A method for manufacturing a superjunction device with wide mesas
EP1701686A4 (en) * 2003-12-19 2009-07-01 Third Dimension 3D Sc Inc Method of manufacturing a superjunction device with conventional terminations
WO2014029810A2 (en) * 2012-08-24 2014-02-27 Roche Diagnostics Gmbh Insulin pump and methods for operating the insulin pump

Similar Documents

Publication Publication Date Title
WO2005065144B1 (en) Planarization method of manufacturing a superjunction device
TWI399815B (en) High voltage structure and methods for vertical power devices with improved manufacturability
US7199006B2 (en) Planarization method of manufacturing a superjunction device
US7052982B2 (en) Method for manufacturing a superjunction device with wide mesas
JP4928947B2 (en) Manufacturing method of super junction device
US6204097B1 (en) Semiconductor device and method of manufacture
US8519476B2 (en) Method of forming a self-aligned charge balanced power DMOS
US6987040B2 (en) Trench MOSFET with increased channel density
CN101800252B (en) Groove-shaped Schottky barrier rectifier and manufacture method thereof
JP2007515080A5 (en)
KR20070116219A (en) Process for high voltage superjunction termination
WO2005065127B1 (en) A method for forming thick dielectric regions using etched trenches
JP2004342660A (en) Semiconductor device and its manufacturing method
US20020175342A1 (en) Two-mask trench schottky diode
JP2009200300A (en) Semiconductor device, and method of manufacturing the same
CN104103519A (en) Method for manufacturing semiconductor power device
US6558984B2 (en) Trench schottky barrier rectifier and method of making the same
US8642427B1 (en) Semiconductor device and method for fabricating the same
US20190058038A1 (en) Forming a Superjunction Transistor Device
US20210320171A1 (en) Superjunction semiconductor device and method of manufacturing superjunction semiconductor device
CN210443554U (en) Shielded gate trench MOSFET with integrated ESD protection
CN115394851B (en) Semiconductor device and method for manufacturing the same
CN112531026B (en) Lateral diffusion metal oxide semiconductor device and manufacturing method thereof
US10546948B1 (en) Electronic device including an insulated gate bipolar transistor having a field-stop region and a process of forming the same
CN1331201C (en) Low-cost method for semiconductor device with high channel density