SEMICONDUCTOR DEVICE

• US 20180076317A1
• Filed: 11/17/2017
• Published: 03/15/2018
• Est. Priority Date: 12/25/2008
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: NAKANO, Yuki, NAKAMURA, Ryota
• Granted Patent: US 10,693,001 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 21/046 using ion implantation
• CPC Class Codes: H01L 21/0485 Ohmic electrodes
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• 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 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/401 Multistep manufacturing processes
• 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 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• CPC Class Codes: H01L 29/66068 the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
• CPC Class Codes: H01L 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/7803 structurally associated with at least one other device assemblies H01L25/00; integrated circuits H01L27/00
• CPC Class Codes: H01L 29/7805 in antiparallel, e.g. freewheel diode
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A semiconductor device includes a semiconductor layer made of SiC. A transistor element having an impurity region is formed in a front surface portion of the semiconductor layer. A first contact wiring is formed on a back surface portion of the semiconductor layer, and defines one electrode electrically connected to the transistor element. The first contact wiring has a first wiring layer forming an ohmic contact with the semiconductor layer without a silicide contact and a second wiring layer formed on the first wiring layer and having a resistivity lower than that of the first wiring layer.

Claims

1. A semiconductor device, comprising:

a semiconductor layer made of SiC, the semiconductor layer having a front surface and a back surface;

a gate trench formed in a surface portion of the semiconductor layer;

a gate insulating film formed on an inner surface of the gate trench;

a gate electrode embedded in the gate trench and on the gate insulating film;

a body region of a second conductivity type formed in the semiconductor layer and defining one part of a side surface of the gate trench;

a source region of a first conductivity type formed on a front surface side of the body region in the semiconductor layer;

a source trench penetrating the source region from the front surface of the semiconductor layer; and

a source electrode integrally extending from a region above the gate electrode to an inner side of the source trench.

2. The semiconductor device according to claim 1, wherein the source trench has a depth that is deeper than that of the gate trench.

3. The semiconductor device according to claim 1, further comprising a drain electrode formed on the back surface of the semiconductor layer.

4. The semiconductor device according to claim 3, wherein the source electrode and/or the drain electrode have a multilayer structure.

5. The semiconductor device according to claim 1, wherein

the body region includes a body contact region formed on a side surface of the source trench, and

the source electrode is in contact with the body contact region in the source trench.

6. The semiconductor device according to claim 5, wherein

the body contact region is covered with the source region from the front surface side of the semiconductor layer, and

the body contact region is not exposed from the front surface of the semiconductor layer.

7. The semiconductor device according to claim 1, further comprising a second conductivity type layer formed in a bottom portion of the gate trench in the semiconductor layer.

8. The semiconductor device according to claim 1, wherein the source electrode is in direct contact with an inner surface of the source trench.

9. The semiconductor device according to claim 1, wherein the source trench has a width that is greater than that of the gate trench.

10. The semiconductor device according to claim 1, further comprising an insulating film covering the gate electrode such that the insulating film is protruded upward from the front surface of the semiconductor layer.

11. The semiconductor device according to claim 4, wherein the multilayer structure includes a polysilicon layer in the portion in contact with the semiconductor layer and a metal layer on the polysilicon layer.

12. The semiconductor device according to claim 11, wherein an intermediate layer containing Ti is interposed between the polysilicon layer and the metal layer.

13. The semiconductor device according to claim 12, wherein

the metal layer has a layer containing Al, and

the intermediate layer has a structure obtained by laminating a Ti layer and a TiN layer in this order from the side of the polysilicon layer.

14. The semiconductor device according to claim 1, wherein

the gate insulating film has a bottom portion located on a bottom surface of the gate trench and a side portion located on a side surface of the gate trench, and

a thickness of the bottom portion and a thickness of the side portion are different from each other.

15. The semiconductor device according to claim 14, wherein the thickness of the bottom portion of the gate insulating film is thinner than the thickness of the side portion of the gate insulating film.

16. The semiconductor device according to claim 15, wherein the thickness of the bottom portion of the gate insulating film is 150 to 500 Å

.

17. The semiconductor device according to claim 15, wherein the thickness of the side portion of the gate insulating film is 300 to 1000 Å

.