Trench MOSFET having shielded electrode integrated with trench Schottky rectifier

• US 8,274,113 B1
• Filed: 05/12/2011
• Issued: 09/25/2012
• Est. Priority Date: 05/12/2011
• Status: Active Grant

• Current Assignee: Force Mos Technology Co., Ltd.
• Original Assignee: Force Mos Technology Co., Ltd.
• Inventors: Hsieh, Fu-Yuan
• Primary Examiner(s): Richards, N Drew
• Assistant Examiner(s): DIALLO, MAMADOU L
• Application Number:
  US13/106,082
• Time in Patent Office: 502 Days
• Field of Search: 257288-350, 257/401, 257/901
• US Class Current: 257/334
• CPC Class Codes: H01L 29/0878 Impurity concentration or distribution
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• 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 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/42372 characterised by the conducting layer, e.g. the length, the sectional shape or the lay-out H01L29/42324 takes precedence
• CPC Class Codes: H01L 29/47 Schottky barrier electrodes H01L29/435 takes precedence
• CPC Class Codes: H01L 29/7806 the other device being a Schottky barrier diode
• 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 29/8725 of the trench MOS barrier type [TMBS]

Abstract

A trench MOSFET having shielded gate in parallel with trench Schottky rectifier is formed on a single chip to further increase the efficiency of the trench MOSFET having shielded electrode. As the size of present device is getting smaller and smaller, the trench Schottky rectifier of this invention is able to be shrink and, at the same time, to achieve lower forward voltage drop and lower reverse leakage current.

Claims

1. An integrated circuit comprising a plurality of trench MOSFETs and a plurality of trench Schottky rectifiers horizontally disposed in to different areas further comprising:

a substrate of a first conductivity type;

an epitaxial layer of said first conductivity type over said substrate said epitaxial layer having a lower doping concentration than said substrate;

a plurality of gate trenches extending into said epitaxial layer;

a trench MOSFET comprising a gate electrode over a shielded electrode in said gate trench wherein said gate electrode and said shielded electrode insulated from each other by an inter-electrode insulation layer wherein said gate electrode insulated from a source region of said first conductivity type and body region of a second conductivity type by a first gate insulation layer and said shield electrode insulated from said epitaxial layer by a second gate insulation layer;

said gate electrode surrounded by said source region encompassed in said body region above said shielded electrode;

said gate electrode connected to a gate metal and said shielded electrode to a source metal;

a source-body contact trench opened in said trench MOSFET through said source region and extended into said body region and filled with a contact metal plug overlying a barrier metal layer therein, said contact metal plug filled in said source-body contact trench connected to said source metal;

a trench Schottky rectifier formed into said epitaxial layer in a different area from said trench MOSFET had having a Schottky barrier layer lined in a Schottky contact trench filled with said contact metal plug overlying said barrier metal layer directly contacting said Schottky contact trench bottom and sidewalls, and between a pair of adjacent gate trenches wherein said source and body regions do not exist, said contact metal plug filled in said Schottky contact trench connected with an anode metal;

said gate trenches in said trench MOSFET and trench Schottky rectifier having a greater trench depth than said Schottky contact trench into said epitaxial layer;

said Schottky rectifier formed at least along sidewalls of said Schottky contact trench in said epitaxial layer, separated from said pair of adjacent gate trenches by said epitaxial layer without having said source and body regions surrounding said Schottky contact trench sidewalls;

at least a gate contact trench in trench MOSFET area opened through a contact insulation layer and extended into said gate electrode in a wide gate trench having greater trench width than said gate trenches in said trench MOSFET area, and filled with said contact metal plug overlying said barrier metal layer therein, said contact metal plug filled in said gate contact trench connected with said gate metal; and

said source metal and said anode metal connected together as a source/anode metal.

2. The integrated circuit of claim 1, wherein said gate trenches in said trench Schottky rectifier are filled with said gate electrode over said shielded electrode.

3. The integrated circuit of claim 2, wherein said gate electrode in said trench Schottky rectifier area extends to a wide gate electrode in a wide gate trench having a greater trench width than said gate trenches in said trench Schottky rectifier area, and at least a gate contact trench in said trench MOSFET area opened through a contact insulation layer and extended into said gate electrode, and filled with said contact metal plug overlying a barrier layer therein, said contact metal plug filled in said gate contact trench connected with said source/anode metal and separated from said gate electrode in said trench MOSFET area.

4. The integrated circuit of claim 1, wherein said gate trenches in said trench Schottky rectifier are filled with said shielded electrode only.

5. The integrated circuit of claim 4, wherein said shielded electrode in said trench Schottky rectifier area extends to a wide shielded electrode in a wide gate trench having a greater trench width than said gate trenches in said trench Schottky rectifier area, and at least a shielded contact trench in said trench MOSFET area opened through a contact insulation layer and extended into said shielded electrode, and filled with said contact metal plug overlying a barrier metal layer therein, said contact metal plug filled in said shielded contact trench connected with said source/anode metal.

6. The integrated circuit of claim 1, wherein said barrier metal layer lines in said source-body and Schottky contact trenches is Ti/TiN or Co/TiN.

7. The integrated circuit of claim 1, wherein said contact metal plug overlying said barrier metal layer is tungsten.

8. The integrated circuit of claim 1, wherein said Schottky barrier layer comprises TiSi2 (Ti Silicide) or CoSi2 (Co Silicide).

9. The integrated circuit of claim 1, wherein said source/anode metal and gate metal are Ti/Aluminum alloys, Ti/TiN/Aluminum alloys, or Ti/TiN/Copper disposed on top of said contact insulation layer and said contact metal plugs.

10. The integrated circuit of claim 1, wherein said Schottky barrier layer lines along sidewalls and bottom of each said Schottky contact trench.

11. The integrated circuit of claim 1, wherein said Schottky barrier layer lines along only sidewalk of each said Schottky contact trench in said epitaxial layer.

12. The integrated circuit of claim 1, wherein said epitaxial layer is a single epitaxial layer.

13. The integrated circuit of claim 1, wherein said epitaxial layer is a double epitaxial layer with a doping concentration of the top epitaxial layer less than that of the bottom epitaxial layer.

14. The integrated circuit of claim 1 further comprises a body contact region of said second conductivity type formed only within said body region wrapping sidewalls and bottom of each said source-body contact trench, but not formed within said trench Schottky rectifier, wherein said body contact region has a higher doping concentration than said body region.

15. The integrated circuit of claim 1 further comprises a Schottky barrier height enhancement region of said first conductivity having doping concentration less than said epitaxial layer, formed within said epitaxial layer in said trench Schottky rectifier and wrapping sidewalls and the bottom of each said Schottky contact trench in said trench Schottky rectifier.

16. The integrated circuit of claim 1 further comprises a Schottky barrier height enhancement region of said second conductivity formed within said epitaxial layer in said trench Schottky rectifier and wrapping sidewalls and bottom of each said Schottky contact trench in said trench Schottky rectifier.

17. The integrated circuit of claim 1, wherein said contact metal plugs filled in said source-body contact trench and said gate contact trench in said trench MOSFET, and said Schottky contact trench in said trench Schottky rectifier extend to cover top surface of said contact insulation layer connected with gate metal and said source/anode metal, respectively.

18. The integrated circuit of claim 17, wherein said metal contact metal plug is Tungsten (W) layer deposited over a Ti/TiN or Co/TiN barrier metal layer, covering said contact insulation layer.

19. The integrated circuit of claim 17, wherein said source/anode metal and said gate metal are Ti/Aluminum alloys, Ti/TiN/Aluminum alloys, or Ti/TiN/Copper disposed on top of said contact metal plugs.

20. The integrated circuit of claim 1, wherein said first gate insulation layer has a thickness along said gate trenches less than that of said second gate insulation layer.