Semiconductor device and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-2017207331-A1
Application number	US-201715404509-A
Country	US
Kind code	A1
Filing date	Jan 12, 2017
Priority date	Jan 18, 2016
Publication date	Jul 20, 2017
Grant date	—

Abstract

A performance of a semiconductor device including an RC-IGBT is improved. An AlNiSi layer (a layer containing aluminum (Al), nickel (Ni), and silicon (Si)) is formed between a back surface of a semiconductor substrate and a back surface electrode. Thus, a favorable ohmic junction can be obtained between the back surface electrode and an N + -type layer constituting a cathode region in an embedded diode, and a favorable ohmic junction can be obtained between the back surface electrode and a P-type layer constituting a collector region in an IGBT. The AlNiSi layer contains 10 at % or more of each of the aluminum (Al), the nickel (Ni), and the silicon (Si).

First claim

What is claimed is:

1 . A semiconductor device comprising:
a semiconductor substrate having a first main surface and a second main surface on an opposite side to the first main surface; a first electrode formed on a side closer to the first main surface; a second electrode formed on a side closer to the second main surface; a first semiconductor layer of a first conductivity type which is formed in a first region in the semiconductor substrate so as to be exposed to the second main surface; a second semiconductor layer of a second conductivity type different from the first conductivity type, which is formed in a second region different from the first region in the semiconductor substrate so as to be exposed to the second main surface; a junction layer which is formed in contact with the first semiconductor layer and the second semiconductor layer and which contains aluminum, silicon, and a first metal having a lower reflectance on a wavelength of visible light beam than a reflectance of the aluminum; and the second electrode formed in contact with the junction layer.

2 . The semiconductor device according to claim 1 ,
wherein the first metal is nickel, titanium, vanadium, molybdenum, or platinum.

3 . The semiconductor device according to claim 1 ,
wherein the junction layer contains 10 at % or more of each of the aluminum, the silicon, and the first metal.

4 . The semiconductor device according to claim 1 ,
wherein a thickness of the junction layer is 100 nm or more and 500 nm or less.

5 . The semiconductor device according to claim 1 ,
wherein the first conductivity type is a P-type, and the second conductivity type is an N-type, and an impurity concentration of the second semiconductor layer is higher than an impurity concentration of the first semiconductor layer.

6 . The semiconductor device according to claim 5 ,
wherein a plurality of the second semiconductor layers are arranged at an equal interval from one another in the first semiconductor layer in a plan view, and the second semiconductor layer has a circular shape in a plan view.

7 . The semiconductor device according to claim 1 , further comprising:
a third semiconductor layer of the first conductivity type which is formed in the semiconductor substrate so as to have a first depth from the first main surface; a fourth semiconductor layer of the second conductivity type which is formed in a third semiconductor layer so as to have a second depth smaller than the first depth from the first main surface; a fifth semiconductor layer of the second conductivity type which is formed in the semiconductor substrate between the third semiconductor layer and the second semiconductor layer and between the first semiconductor layer and the second semiconductor layer; a trench which is formed in the semiconductor substrate so as to penetrate the fourth semiconductor layer and the third semiconductor layer from the first main surface and which reaches the fifth semiconductor layer; a third electrode formed inside the trench through an insulating film; and the first electrode electrically connected to the third semiconductor layer and the fourth semiconductor layer.

8 . A semiconductor device comprising:
a semiconductor substrate having a first main surface and a second main surface on an opposite side to the first main surface; a first electrode formed on a side closer to the first main surface; a second electrode formed on a side closer to the second main surface; a first semiconductor layer of an N-type conductivity which is formed in the semiconductor substrate so as to be exposed to the second main surface; a junction layer which is formed in contact with the first semiconductor layer and which contains aluminum, silicon, and a first metal having a lower reflectance on a wavelength of visible light beam than a reflectance of the aluminum; and the second electrode formed in contact with the junction layer.

9 . The semiconductor device according to claim 8 ,
wherein the first metal is nickel, titanium, vanadium, molybdenum, or platinum.

10 . The semiconductor device according to claim 8 ,
wherein the junction layer contains 10 at % or more of each of the aluminum, the silicon, and the first metal.

11 . The semiconductor device according to claim 8 ,
wherein a thickness of the junction layer is 100 nm or more and 500 nm or less.

12 . The semiconductor device according to claim 8 , further comprising:
a second semiconductor layer of the N-type conductivity which is formed in the semiconductor substrate so as to be exposed to the first main surface; a third semiconductor layer of a P-type conductivity which is formed in the semiconductor substrate between the first semiconductor layer and the second semiconductor layer; a trench which is formed in the semiconductor substrate so as to penetrate the second semiconductor layer and the third semiconductor layer from the first main surface and which reaches the first semiconductor layer; a third electrode formed inside the trench through an insulating film; and the first electrode electrically connected to the second semiconductor layer.

13 . The semiconductor device according to claim 8 , further comprising:
a second semiconductor layer of a P-type conductivity which is formed in the semiconductor substrate between the first semiconductor layer and the first main surface so as to be exposed to the first main surface; and the first electrode formed in contact with the second semiconductor layer.

14 . A method of manufacturing a semiconductor device, comprising the steps of:
(a) ion-implanting first impurities of a first conductivity type into a first region in a back surface of a semiconductor substrate to form a first semiconductor layer exposed to the back surface of the semiconductor substrate; (b) ion-implanting second impurities of a second conductivity type different from the first conductivity type into a second region different from the first region in the back surface of the semiconductor substrate to form a second semiconductor layer exposed to the back surface of the semiconductor substrate; (c) forming a first metal film on the back surface of the semiconductor substrate; (d) forming a second metal film on the first metal film; (e) irradiating a stacked film formed of the first metal film and the second metal film with laser beam to form a junction layer contacting the back surface of the semiconductor substrate; and (f) forming a back surface electrode in contact with the junction layer, wherein the first metal film is made of an aluminum alloy containing silicon, the second metal film is made of a first metal having a lower reflectance on a wavelength of visible light beam than a reflectance of aluminum, and the junction layer is a layer containing the aluminum, the silicon and the first metal.

15 . The method of manufacturing the semiconductor device according to claim 14 ,
wherein the first metal is nickel, titanium, vanadium, molybdenum, or platinum.

16 . The method of manufacturing the semiconductor device according to claim 14 ,
wherein the junction layer contains 10 at % or more of each of the aluminum, the silicon, and the first metal.

17 . The method of manufacturing the semiconductor device according to claim 14 ,
wherein a thickness of the junction layer is 100 nm or more and 500 nm or less.

18 . The method of manufacturing the semiconductor device according to claim 14 ,
wherein the first conductivity type is a P-type, and t

Assignees

• Renesas Electronics Corp

Inventors

• Nakanishi Sho
• Fujii Yuji

Classifications

• H10P30/20

  into semiconductor materials, e.g. for doping · CPC title

• H10D64/0115

  to silicon carbide · CPC title

• H10D64/0114

  to diamond, semiconducting diamond-like carbon or graphene · CPC title

• H10D64/0112

  using conductive layers comprising silicides · CPC title

• H10W20/20

  Interconnections within wafers or substrates, e.g. through-silicon vias [TSV] · CPC title