Trench gate power semiconductor device

• US 7,939,886 B2
• Filed: 11/22/2005
• Issued: 05/10/2011
• Est. Priority Date: 11/22/2005
• Status: Active Grant

• Current Assignee: Shindengen Electric Manufacturing Company Limited
• Original Assignee: Shindengen Electric Manufacturing Company Limited
• Inventors: Watanabe, Yuji, Oshima, Kunihito, Matsuyama, Kazushige, Sasaoka, Fuminori, Takemori, Toshiyuki, Itoi, Masato
• Primary Examiner(s): Dang; Phuc T
• Application Number:
  US12/094,312
• Publication Number:
  US 20080315301A1
• Time in Patent Office: 1,995 Days
• Field of Search: 257/330, 257/331, 257/365, 257/382, 257/E29.125, 257/E29.257, 438/195, 438/585, 438/588
• US Class Current: 257/331
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• 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 29/4238 characterised by the surface lay-out
• CPC Class Codes: H01L 29/66348 with a recessed gate
• 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 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/7805 in antiparallel, e.g. freewheel diode
• CPC Class Codes: H01L 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A trench gate power MOSFET (1) includes: an n⁻-type epitaxial layer (12); a p-type body region (20) formed in the vicinity of an upper surface of the n⁻-type epitaxial layer (12); a plurality of trenches (14) formed so as to reach the n⁻-type epitaxial layer (12) from an upper surface of the p-type body region (20); and gates (18) formed in the trenches (14). In some regions facing the p-type body region (20) in the n⁻-type epitaxial layer (12), p-type carrier extracting regions (26a, 26b, 26c) are formed. According to the trench gate power MOSFET (1), holes generated in a cell region can be effectively collected through the p-type carrier extracting regions (26a, 26b, 26c) so as to further increase a speed of the switching operation.

Claims

1. A trench gate power semiconductor device comprising:

a semiconductor layer of first conductive type;

a body region of second conductive type opposite to the first conductive type, the body region formed in a vicinity of an upper surface of the semiconductor layer of first conductive type;

a plurality of first trenches formed so as to reach the semiconductor layer of first conductive type from an upper surface side of the body region of second conductive type; and

gates formed in the plurality of first trenches, wherein

a second trench of a depth smaller than a depth of the body region of second conductive type and including a metal layer connected with an electrode different from a gate electrode of electrodes formed on an upper surface of the semiconductor layer of first conductive type therein is formed in the body region of second conductive type, and

a carrier extracting region of second conductive type is formed on a lower surface of the second trench such that the carrier extracting region is connected to the metal layer and reaches the semiconductor layer of first conductive type.

2. A trench gate power semiconductor device according to claim 1, wherein the second trench is formed in all inter-trench regions which are respectively sandwiched between two neighboring first trenches of the plurality of first trenches.

3. A trench gate power semiconductor device according to claim 1, wherein the second trench is formed in a portion of regions of all inter-trench regions which are respectively sandwiched between two neighboring first trenches of the plurality of first trenches.

4. A trench gate power semiconductor device according to claim 1, wherein the second trench is formed in partial or whole regions of a portion of inter-trench regions of inter-trench regions which are respectively sandwiched between two neighboring first trenches of the plurality of first trenches.

5. A trench gate power semiconductor device according to claim 1, wherein the second trench is formed in a peripheral region further outside an outermost first trench of the plurality of first trenches.

6. A trench gate power semiconductor device according to claim 2, wherein the second trench is formed in a peripheral region outside an outermost first trench of the plurality of first trenches.

7. A trench gate power semiconductor device according to claim 6, wherein the second trench formed in the peripheral region has a width larger than a width of the second trench formed in the inter-trench region.

8. A trench gate power semiconductor device according to claim 6, wherein the carrier extracting region of second conductive type formed in the peripheral region is formed so as to reach a position deeper than the carrier extracting region of second conductive type formed in the inter-trench region.

9. A trench gate power semiconductor device according to claim 1, wherein the carrier extracting region of second conductive type is formed so as to reach a position of a depth larger than a depth of the plurality of first trenches.

10. A trench gate power semiconductor device according to claim 1, wherein on a portion of the carrier extracting region of second conductive type which is brought into contact with the second trench, a contact layer for reducing contact resistance with the metal layer filled in an inside of the second trench is formed.

11. A trench gate power semiconductor device according to claim 1, wherein the trench gate power semiconductor device is a power MOSFET.

12. A trench gate power semiconductor device according to claim 1, wherein the trench gate power semiconductor device is an IGBT.