Manufacturing method of silicon carbide semiconductor device

Patent metadata

Field	Value
Publication number	US-10748780-B2
Application number	US-201916353670-A
Country	US
Kind code	B2
Filing date	Mar 14, 2019
Priority date	Oct 5, 2016
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

In a manufacturing method of a silicon carbide semiconductor device, a semiconductor substrate made of silicon carbide and on which a base layer is formed is prepared, a trench is provided in the base layer, a silicon carbide layer is epitaxially formed on a surface of the base layer while filling the trench with the silicon carbide layer, the sacrificial layer is planarized by reflow after forming the sacrificial layer, and the silicon carbide layer is etched back together with the planarized sacrificial layer by dry etching under an etching condition in which an etching selectivity of the silicon carbide layer to the sacrificial layer is 1.

First claim

What is claimed is:

1. A manufacturing method of a silicon carbide semiconductor device, comprising:
preparing a semiconductor substrate made of silicon carbide and on which a base layer is formed;
providing a trench in the base layer;
epitaxially growing a silicon carbide layer on a surface of the base layer while filling the trench with the silicon carbide layer;
forming a sacrificial layer on a surface of the silicon carbide layer;
planarizing the sacrificial layer by reflow after forming the sacrificial layer; and
etching back the silicon carbide layer together with the sacrificial layer that is planarized by dry etching under an etching condition in which an etching selectivity of the silicon carbide layer to the sacrificial layer is 1,
wherein
the providing of the trench includes providing an alignment trench at a position different from the trench in the base layer,
the epitaxially growing the silicon carbide layer includes forming the silicon carbide layer to fill the alignment trench with the silicon carbide layer,
the forming the sacrificial layer includes forming the sacrificial layer also on the silicon carbide layer formed to fill the alignment trench, and
the etching back is performed until a facet included in a recess provided at a position corresponding to the alignment trench in the surface of the silicon carbide layer is removed.

2. The manufacturing method according to claim 1 , wherein
the etching back includes exposing a surface of the base layer and leaving the silicon carbide layer only in the trench.

3. The manufacturing method according to claim 1 , wherein
the forming the sacrificial layer includes forming one of PSG, BPSG, or SOG as the sacrificial layer.

4. The manufacturing method according to claim 1 , wherein
the preparing the semiconductor substrate on which the base layer is formed includes preparing a silicon carbide substrate of a first conductivity type or a second conductivity type as the semiconductor substrate, and forming, as the base layer, a drift layer of the first conductivity type made of silicon carbide having an impurity concentration lower than an impurity concentration of the silicon carbide substrate, a base region of the second conductivity type made of silicon carbide, and a source region of the first conductivity type made of silicon carbide having an impurity concentration higher than the impurity concentration of the drift layer on the silicon carbide substrate in a stated order,
the etching back includes forming a deep layer of the second conductivity type in the trench by performing the etching back until a surface of the source region is exposed, and
the manufacturing method further comprising:
after forming the deep layer, forming a trench gate structure in which a gate trench deeper than the base region is provided from the surface of the source region, a gate insulating film is formed on an inner wall surface of the gate trench, and a gate electrode is formed on the gate insulating film;
forming a source electrode electrically connected to the source region and the deep layer; and
forming a drain electrode on a rear surface of the semiconductor substrate.

5. The manufacturing method according to claim 1 , wherein
the preparing the semiconductor substrate on which the base layer is formed includes preparing a silicon carbide substrate of a first conductivity type as the semiconductor substrate, and forming, as the base layer, a drift layer of a first conductivity type made of silicon carbide having an impurity concentration lower than an impurity concentration of the silicon carbide on the silicon carbide substrate,
the etching back includes forming a deep layer of a second conductivity type in the trench by performing the etching back until a surface of the drift layer is exposed, and
the manufacturing method further comprising:
forming a Schottky electrode electrically connected to the drift layer and the deep layer; and
forming an ohmic electrode on a rear surface of the semiconductor substrate.

Assignees

• Denso Corp
• Toyota Motor Co Ltd

Inventors

• Takagi Shigeyuki
• Shimomura Masaki
• Takeuchi Yuichi
• Suzuki Katsumi
• Aoi Sachiko

Classifications

• H10P50/283

  by chemical means · CPC title

• H10P14/6529

  by exposure to a gas or vapour · CPC title

• H10W46/301

  for alignment · CPC title

• H10W46/00 Primary

  Marks applied to devices, e.g. for alignment or identification · CPC title

• H10P50/242 Primary

  of Group IV materials · CPC title