Structure for avalanche improvement of ultra high density trench MOSFET

• US 20060273384A1
• Filed: 09/26/2005
• Published: 12/07/2006
• Est. Priority Date: 06/06/2005
• Status: Abandoned Application

• Current Assignee: M-Mos Sdn., Bhd., M-Mos Semiconductor Sdn. Bhd.
• Original Assignee: M-Mos Sdn., Bhd.
• Inventors: Hshieh, Fwu-Iuan
• Application Number:
  US11/236,007
• Publication Number:
  US 20060273384A1
• Time in Patent Office: Days
• US Class Current: 257/330
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05655 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/371 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/37124 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/37144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/37147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/37155 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/48624 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48655 Nickel (Ni) as principal constituent
• CPC Class Codes: H01L 2224/48724 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48755 Nickel (Ni) as principal constituent
• CPC Class Codes: H01L 2224/4903 Connectors having different sizes, e.g. different diameters
• CPC Class Codes: H01L 2224/49051 Connectors having different shapes
• CPC Class Codes: H01L 2224/49111 the connectors connecting two common bonding areas, e.g. Litz or braid wires
• CPC Class Codes: H01L 2224/73221 Strap and wire connectors
• CPC Class Codes: H01L 2224/83801 : Soldering or alloying
• CPC Class Codes: H01L 2224/85 : using a wire connector
• CPC Class Codes: H01L 24/26 : Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
• CPC Class Codes: H01L 24/37 : of an individual strap connector
• CPC Class Codes: H01L 24/40 : of an individual strap connector
• CPC Class Codes: H01L 24/45 : of an individual wire connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/49 : of a plurality of wire connectors
• CPC Class Codes: H01L 24/83 : using a layer connector
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• CPC Class Codes: H01L 29/41766 : with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/456 : on silicon
• CPC Class Codes: H01L 29/66727 : with a step of recessing the source electrode
• CPC Class Codes: H01L 29/66734 : with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7813 : with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01018 : Argon [Ar]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01028 : Nickel [Ni]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01042 : Molybdenum [Mo]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• CPC Class Codes: H01L 2924/0133 : Ternary Alloys
• CPC Class Codes: H01L 2924/04941 : TiN
• CPC Class Codes: H01L 2924/1305 : Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/1306 : Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/20755 : larger or equal to 50 microns less than 60 microns
• CPC Class Codes: H01L 2924/2076 : equal to or larger than 100 microns
• CPC Class Codes: H01L 2924/30105 : Capacitance

Abstract

A trenched metal oxide semiconductor field effect transistor (MOSFET) cell that includes a trenched gate surrounded by a source region encompassed in a body region above a drain region disposed on a bottom surface of a substrate. The MOSFET cell further includes a source-body contact trench opened with sidewalls substantially extend vertically relative to a top surface into the source and body regions and filled with contact metal plug. A body-resistance reduction region doped with body-doped is formed to surround the source-body contact trench to reduce a body-region resistance between the source-body contact metal and the trenched gate to improve an avalanche capability.

Claims

1. A trenched metal oxide semiconductor field effect transistor (MOSFET) cell comprising a trenched gate surrounded by a source region encompassed in a body region above a drain region disposed on a bottom surface of a substrate, wherein said MOSFET cell further comprising:

a source-body contact trench opened with sidewalls extended substantially vertical relative to a top surface into said source and body regions and filled with contact metal plug; and

a body-resistance-reduction region doped with a body-resistance-reduction-dopant disposed in said body region immediately near said source-body contact trench whereby an avalanche capability of said MOSFET cell is enhanced.

2. The MOSFET cell of claim 1 wherein:

said body-resistance-reduction-dopant is a dopant of a same conductivity type as a body dopant doped in said body region.

3. The MOSFET cell of claim 1 wherein:

said body-resistance-reduction region further surrounding of said source-body contact trench.

4. The MOSFET cell of claim 1 wherein:

said body-resistance-reduction region further disposed immediately below a bottom of said source-body contact trench.

5. The MOSFET cell of claim 1 wherein:

said sidewalls of said source-body contact trench converging with a small tilted angle relative to a perpendicular direction to said top surface of said substrate.

6. The MOSFET cell of claim 1 further comprising:

a buried region doped with a source-dopant disposed below said body region whereby said avalanche capability is further enhanced.

7. The MOSFET cell of claim 1 wherein:

the contact metal plug further comprising a Ti/TiN barrier layer surrounding a tungsten core as a source-body contact metal.

8. The MOSFET cell of claim 1 further comprising:

an insulation layer covering a top surface over said MOSFET cell wherein said source body contact trench is opened through said insulation layer; and

a thin resistance-reduction conductive layer disposed on a top surface covering said insulation layer and contacting said contact metal plug whereby said resistance-reduction conductive layer having a greater area than a top surface of said contact metal plug for reducing a source-body resistance.

9. The MOSFET cell of claim 1 wherein:

said contact metal plug filled in said source body contact trench comprising a substantially cylindrical shaped plug.

10. The MOSFET cell of claim 1 wherein:

the source body contact trench further comprising an oxide trench formed by an oxide-etch through an oxide layer covering a top surface said MOSFET device.

11. The MOSFET cell of claim 1 wherein:

the source body contact trench further comprising a trench formed by etching with different gas ratios of C4F8/CO/O2/Ar plasma for an oxide etch and CF4/O2/Cl2 plasma for a dry silicon etch for extending said sidewalls of said source-body contract trench into said substrate with a small tilt angle relative to a perpendicular direction to a top surface of said substrate.

12. The MOSFET cell of claim 1 wherein:

the source body contact trench further comprising a trench formed by etching with different gas ratios of C3F6/CO/O2/Ar plasma for an oxide etch and CF4/O2/Cl2 plasma for a dry silicon etch for extending said sidewalls of said source-body contract trench into said substrate with a small tilt angle relative to a perpendicular direction to a top surface of said substrate.

13. The MOSFET cell of claim 1 wherein:

the source body contact trench further comprising a trench formed by etching with different gas ratios of C4F8/CO/O2/Ar plasma for an oxide etch and HBr/O2/Cl2 plasma for a dry silicon etch for extending said sidewalls of said source-body contract trench into said substrate with a small tilt angle relative to a perpendicular direction to a top surface of said substrate.

14. The MOSFET cell of claim 1 wherein:

the source body contact trench further comprising a trench formed by etching with different gas ratios of C3F6/CO/O2/Ar plasma for an oxide etch and HBr/O2/Cl2 plasma for a dry silicon etch for extending said sidewalls of said source-body contract trench into said substrate with a small tilt angle relative to a perpendicular direction to a top surface of said substrate.

15. The MOSFET cell of claim 1 wherein:

the source body contact trench further comprising a trench opened by a dry oxide and silicon etch whereby a critical dimension (CD) of said source-body contact trench is better controlled.

16. The MOSFET cell of claim 1 wherein:

the contact metal plug further contacts said source region on trench sidewalls of said source body contact trench and contact metal plug contacts said body region through a bottom surface of said source body contact trench.

17. The MOSFET cell of claim 1 wherein:

said MOSFET cell further comprising a N-channel MOSFET cell.

18. The MOSFET cell of claim 1 wherein:

said MOSFET cell further comprising a P-channel MOSFET cell.

19. The MOSFET cell of claim 1 wherein:

said body-resistance-reduction region further surrounding said source-body contact trench extending over volumes in said body surrounding sidewalls and bottom portions of said source-body contact trench.

20. A method for manufacturing a trenched metal oxide semiconductor field effect transistor (MOSFET) cell comprising a step of forming said MOSFET cell with a trenched gate surrounded by a source region encompassed in a body region above a drain region disposed on a bottom surface of a substrate, the method further comprising:

covering said MOSFET cell with an insulation layer and applying a contact mask for opening a source-body contact trench with sidewalls substantially perpendicular to a top surface of said insulation layer into said source and body regions; and

forming a body-resistance-reduction region by implanting a body-resistance-reduction-dopant in said body region immediately near said source-body contact trench whereby an avalanche capability of said MOSFET cell is enhanced.

21. The method of claim 20 wherein:

said step of implanting said body-resistance-reduction-dopant is a step of implanting a dopant of a same conductivity type as a body dopant doped in said body region.

22. The method of claim 20 wherein:

said step of forming said body-resistance-reduction region further comprising a step of forming said body-resistance-reduction region surrounding said source-body contact trench.

23. The method of claim 20 wherein:

said step of forming said body-resistance-reduction region further comprising a step of forming said body-resistance-reduction region immediately below a bottom of said source-body contact trench.

24. The method of claim 20 wherein:

said step of opening said source-body contact trench further comprising a step of opening said source-body contact trench with said sidewalls converging with a small tilted angle relative to a perpendicular direction to said top surface of said substrate.

25. The MOSFET cell of claim 20 further comprising:

forming a buried region by implanting source-dopant ions below said body region for further enhancing said avalanche capability.

26. The method of claim 20 further comprising:

filling said source-body contact trench with contact metal plug.

27. The method of claim 20 wherein:

said step of forming said source body contact trench further comprising a carrying out an oxide etch with different gas ratios of C4F8/CO/O2/Ar plasma followed by carrying out a dry silicon etch with CF4/O2/Cl2 plasma for extending said sidewalls of said source-body contract trench into said substrate with a small tilt angle relative to a perpendicular direction to a top surface of said substrate.

28. The method of claim 20 wherein:

said step of forming said source body contact trench further comprising a carrying out an oxide etch with different gas ratios of C3F6/CO/O2/Ar plasma followed by carrying out a dry silicon etch with CF4/O2/Cl2 plasma for extending said sidewalls of said source-body contract trench into said substrate with a small tilt angle relative to a perpendicular direction to a top surface of said substrate.

29. The method of claim 20 wherein:

said step of forming said source body contact trench further comprising a carrying out an oxide etch with different gas ratios of C4F8/CO/O2/Ar plasma followed by carrying out a dry silicon etch with HBr/O2/Cl2 plasma for extending said sidewalls of said source-body contract trench into said substrate with a small tilt angle relative to a perpendicular direction to a top surface of said substrate.

30. The method of claim 20 wherein:

said step of forming said source body contact trench further comprising a carrying out an oxide etch with different gas ratios of C3F6/CO/O2/Ar plasma followed by carrying out a dry silicon etch with HBr/O₂/Cl2 plasma for extending said sidewalls of said source-body contract trench into said substrate with a small tilt angle relative to a perpendicular direction to a top surface of said substrate.

31. The method of claim 20 wherein:

said step of forming said body-resistance-reduction region further comprising a step of forming said body-resistance-reduction region surrounding both sidewalls and bottom portions of said source-body contact trench.