Producing a semiconductor device by epitaxial growth

Patent metadata

Field	Value
Publication number	US-9647083-B2
Application number	US-201615142992-A
Country	US
Kind code	B2
Filing date	Apr 29, 2016
Priority date	Apr 30, 2015
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

A method of producing a semiconductor device is presented. The method comprises: providing a semiconductor substrate having a surface; epitaxially growing, along a vertical direction (Z) perpendicular to the surface, a back side emitter layer on top of the surface, wherein the back side emitter layer has dopants of a first conductivity type or dopants of a second conductivity type complementary to the first conductivity type; epitaxially growing, along the vertical direction (Z), a drift layer having dopants of the first conductivity type above the back side emitter layer, wherein a dopant concentration of the back side emitter layer is higher than a dopant concentration of the drift layer; and creating, either within or on top of the drift layer, a body region having dopants of the second conductivity type, a transition between the body region and the drift layer forming a pn-junction (Zpn). Epitaxially growing the drift layer includes creating, within the drift layer, a dopant concentration profile (P) of dopants of the first conductivity type along the vertical direction (Z), the dopant concentration profile (P) in the drift layer exhibiting a variation of a concentration of dopants of the first conductivity type along the vertical direction (Z).

First claim

The invention claimed is:

1. A method of producing a semiconductor device, comprising:
providing a semiconductor substrate having a surface;
epitaxially growing, along a vertical direction perpendicular to the surface, a back side emitter layer on top of the surface, wherein the back side emitter layer has dopants of a first conductivity type or dopants of a second conductivity type complementary to the first conductivity type;
epitaxially growing, along the vertical direction, a drift layer having dopants of the first conductivity type above the back side emitter layer, wherein a dopant concentration of the back side emitter layer is higher than a dopant concentration of the drift layer; and
creating, either within or on top of the drift layer, a body region having dopants of the second conductivity type, a transition between the body region and the drift layer forming a pn-junction;

wherein epitaxially growing the drift layer includes creating, within the drift layer, a dopant concentration profile of dopants of the first conductivity type along the vertical direction, the dopant concentration profile exhibiting a variation of a concentration of dopants of the first conductivity type along the vertical direction.

2. The method of claim 1 , wherein a maximum of the dopant concentration profile in the drift region is higher than a concentration of dopants of the first conductivity type at the pn-junction by a factor of at least 2.

3. The method of claim 1 , further comprising epitaxially growing, along the vertical direction, a buffer layer on top of the back side emitter layer before epitaxially growing the drift layer on top of the buffer layer, the buffer layer having dopants of the first conductivity type at a higher dopant concentration than the drift layer.

4. A method of producing a semiconductor device, comprising:
providing a semiconductor substrate having a surface;
epitaxially growing, along a vertical direction perpendicular to the surface, a back side emitter layer on top of the surface, wherein the back side emitter layer has dopants of a first conductivity type or dopants of a second conductivity type complementary to the first conductivity type;
epitaxially growing, along the vertical direction, a buffer layer on top of the back side emitter layer, the buffer layer having dopants of the first conductivity type;
epitaxially growing, along the vertical direction, a drift layer having dopants of the first conductivity type on top of the buffer layer, wherein each of a dopant concentration of the back side emitter layer and a dopant concentration of the buffer layer is higher than a dopant concentration of the drift layer; and
creating, either within or on top of the drift layer, a body region having dopants of the second conductivity type, a transition between the body region and the drift layer forming a pn-junction;

wherein epitaxially growing the buffer layer includes creating, within the buffer layer, a dopant concentration profile of dopants of the first conductivity type along the vertical direction, the dopant concentration profile exhibiting a variation of a concentration of dopants of the first conductivity type along the vertical direction.

5. The method of claim 4 , wherein the dopant concentration profile in the buffer layer exhibits at least one of a step-like increase and a step-like decrease of the dopant concentration along the vertical direction.

6. The method of claim 4 , wherein the dopant concentration profile in the buffer layer comprises at least one box-shaped section, wherein a first lateral edge of the at least one box-shaped section comprises a step-like increase of the dopant concentration along the vertical direction, and wherein a second lateral edge of the box-shaped section comprises a step-like decrease of the dopant concentration along the vertical direction.

7. The method of claim 5 , wherein the dopant concentration varies along the vertical direction by a factor of at least 2 over a distance of 1 μm at the at least one step-like increase and/or at the least one step-like decrease of the dopant concentration profile.

8. The method of claim 4 , wherein the dopant concentration profile in the buffer layer comprises at least one linear section exhibiting one of a linear increase and a linear decrease of the dopant concentration along the vertical direction over a distance of at least 10% of the total extension of the buffer layer along the vertical direction.

9. The method of claim 4 , wherein the dopant concentration profile in the buffer layer exhibits a plurality of local maxima.

10. The method of claim 9 , wherein the dopant concentration profile in the buffer layer exhibits at least one local minimum being located between two neighboring local maxima of the plurality of local maxima, and wherein a dopant concentration at the local minimum is lower than the dopant concentration of each of the neighboring local maxima by a factor of at least 2.

11. The method of claim 1 , wherein creating a dopant concentration profile by epitaxially growing, along the vertical direction, a semiconductor layer comprises a time dependent admixture of dopants.

12. The method of claim 4 , wherein creating a dopant concentration profile by epitaxially growing, along the vertical direction, a semiconductor layer comprises a time dependent admixture of dopants.

13. The method of one claim 1 , wherein creating the body region comprises epitaxially growing the body region on top of the drift layer along the vertical direction.

14. The method of claim 4 , wherein creating the body region comprises epitaxially growing the body region on top of the drift layer along the vertical direction.

Assignees

• Infineon Technologies Ag
• Infineon Technologies Austria Ag

Inventors

• Schloegl Daniel
• Baumgartl Johannes
• Kuenle Matthias
• Lercher Erwin
• Schulze Hans-Joachim
• Weiss Christoph

Classifications

• H10P30/22

  using masks · CPC title

• H10P30/20

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

• H10P14/3438

  Doping during depositing · CPC title

• H10P14/40

  of conductive or resistive materials · CPC title

• H10P14/24

  using chemical vapour deposition [CVD] · CPC title