Semiconductor device with a porous portion, wafer composite and method of manufacturing a semiconductor device

Patent metadata

Field	Value
Publication number	US-11476111-B2
Application number	US-202016811192-A
Country	US
Kind code	B2
Filing date	Mar 6, 2020
Priority date	Mar 6, 2019
Publication date	Oct 18, 2022
Grant date	Oct 18, 2022

Abstract

A semiconductor substrate includes a base portion, an auxiliary layer and a surface layer. The auxiliary layer is formed on the base portion. The surface layer is formed on the auxiliary layer. The surface layer is in contact with a first main surface of the semiconductor substrate. The auxiliary layer has a different electrochemical dissolution efficiency than the base portion and the surface layer. At least a portion of the auxiliary layer and at least a portion of the surface layer are converted into a porous structure. Subsequently, an epitaxial layer is formed on the first main surface.

First claim

What is claimed is:

1. A method of manufacturing a semiconductor device, comprising:
providing a semiconductor substrate that comprises a base portion, an auxiliary layer on the base portion, and a surface layer on the auxiliary layer, wherein the surface layer is in contact with a first main surface of the semiconductor substrate, and wherein the auxiliary layer has a higher electrochemical dissolution efficiency than the base portion and the surface layer;
converting into a porous structure:
(i) at least a portion of the auxiliary layer that, before the converting, has the higher electrochemical dissolution efficiency than the base portion and the surface layer; and
(ii) at least a portion of the surface layer; and

forming, after the converting, an epitaxial layer on the first main surface.

2. The method according to claim 1 , comprising:
separating the epitaxial layer from the base portion along the porous structure.

3. The method according to claim 1 , wherein
the epitaxial layer and the semiconductor substrate differ in at least one main constituent.

4. The method according to claim 1 , wherein
a mean net dopant concentration in the auxiliary layer is at least 100 times a mean net dopant concentration in the surface layer.

5. The method according to claim 1 , wherein
the surface layer and the auxiliary layer have a same conductivity type.

6. The method according to claim 1 , wherein
the semiconductor substrate is a silicon carbide substrate.

7. The method according to claim 1 , wherein
the first main surface is exposed during formation of the porous structure.

8. The method according to claim 1 , comprising:
forming, prior to the converting, a mask on the first main surface, wherein mask openings in the mask expose first sections of the surface layer.

9. The method according to claim 8 , comprising:
recessing, prior to the converting, the first sections to form pits in the first main surface.

10. The method according to claim 8 , comprising:
implanting, prior to the converting, dopants into the first sections.

11. The method according to claim 9 , comprising:
implanting, prior to the converting, dopants into the first sections.

12. A method of manufacturing a semiconductor device, comprising:
providing a semiconductor substrate, wherein the semiconductor substrate comprises a base portion and an auxiliary layer on the base portion;
forming pits in the auxiliary layer; and
converting at least a portion of the auxiliary layer into a porous structure, wherein the porous structure comprises a layered portion and laterally separated columnar portions, and wherein the layered portion is formed at a distance to a first main surface of the semiconductor substrate and the laterally separated columnar portions extend from the pits to the layered portion.

13. The method according to claim 12 , comprising:
forming, after the converting, an epitaxial layer on the first main surface; and
separating the epitaxial layer from the base portion along the layered portion.

Assignees

• Infineon Technologies Ag

Inventors

• Moder Iris
• Goller Bernhard
• Hoechbauer Tobias Franz Wolfgang
• Rupp Roland
• Santos Rodriguez Francisco Javier
• Schulze Hans-Joachim

Classifications

• H10P90/15

  by making porous regions on the surface · CPC title

• H10P50/69

  using masks for semiconductor materials · CPC title

• H10P30/40

  into insulating materials · CPC title

• H10P14/6349

  Deposition of epitaxial materials · CPC title

• H10P14/2904

  Silicon carbide · CPC title