Source contact and metal scheme for high density trench MOSFET

• US 20060273380A1
• Filed: 06/06/2005
• 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:
  US11/147,075
• Publication Number:
  US 20060273380A1
• Time in Patent Office: Days
• US Class Current: 257/330
• CPC Class Codes: H01L 2224/05552 in top view
• CPC Class Codes: H01L 2224/05554 being square
• 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 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/37147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/40245 the item being metallic
• CPC Class Codes: H01L 2224/40247 Connecting the strap to a bond pad of the item
• 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 2224/84 : using a strap connector
• CPC Class Codes: H01L 2224/84801 : 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 24/84 : using a strap 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 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01042 : Molybdenum [Mo]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01072 : Hafnium [Hf]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/04941 : TiN
• 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 2924/181 : Encapsulation
• 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 perpendicular to a top surface into the source and body regions and filled with contact metal plug.

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 substantially perpendicular to a top surface into said source and body regions and filled with contact metal plug.

2. 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.

3. 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.

4. The MOSFET cell of claim 1 wherein:

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

5. The MOSFET cell of claim 3 further comprising:

a thick front metal layer disposed on top of said resistance-reduction layer for providing a contact layer for a wire or wireless bonding package.

6. The MOSFET cell of claim 1 further comprising:

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.

7. The MOSFET cell of claim 1 further comprising:

the source body contact trench further comprising a silicon trench formed by a silicon-etch after an oxide-etch for extending said source-body contract trench into a silicon substrate.

8. The MOSFET cell of claim 1 further comprising:

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.

9. The MOSFET cell of claim 1 further comprising:

the source body contact trench further comprising a trench opened by a dry oxide and silicon etch followed by a wet oxide layer to form irregular shaped trench sidewalls.

10. 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.

11. The MOSFET cell of claim 3 wherein:

said thin resistance-reduction conductive layer comprising a titanium (Ti) layer.

12. The MOSFET cell of claim 3 wherein:

said thin resistance-reduction conductive layer comprising a titanium nitride (TiN) layer.

13. The MOSFET cell of claim 5 wherein:

said front thick metal layer comprising an aluminum layer.

14. The MOSFET cell of claim 5 wherein:

said front thick metal layer comprising an AlCu layer.

15. The MOSFET cell of claim 5 wherein:

said front thick metal layer comprising an AlCuSi layer.

16. The MOSFET cell of claim 5 wherein:

said front thick metal layer comprising an Al/NiAu layer.

17. The MOSFET cell of claim 5 wherein:

said front thick metal layer comprising an AlCu/NiAu layer.

18. The MOSFET cell of claim 5 wherein:

said front thick metal layer comprising an AlCuSi/NiAu layer.

19. The MOSFET cell of claim 5 wherein:

said front thick metal layer comprising an NiAg layer.

20. The MOSFET cell of claim 5 wherein:

said front thick metal layer comprising an NiAu layer.

21. The MOSFET cell of claim 1 wherein:

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

22. The MOSFET cell of claim 1 wherein:

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

23. The MOSFET cell of claim 1 wherein:

said source-body contact trench having stepwise sidewalls and said contact metal plug filled in said source-body contact trench comprising a substantially cup shaped plug having a wider top contact area.

24. The MOSFET cell of claim 5 further comprising:

aluminum wires for connecting said thick front metal layer to a lead frame.

25. The MOSFET cell of claim 5 further comprising:

gold wires for connecting said thick front metal layer to a lead frame.

26. The MOSFET cell of claim 5 further comprising:

a cooper plate for connecting said thick front metal layer to a lead frame.

27. 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.

28. The method of claim 27 further comprising:

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

29. The method of claim 27 wherein:

said step of covering said MSOFET cell with an insulation layer further comprising a step of depositing two different oxide layers on top of said MOSFET cell and applying a differential oxide etch to form a source-body contact trench having a step-wise sidewall with a wider top opening.