Silicon carbide semiconductor device and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-10790201-B2
Application number	US-201916278314-A
Country	US
Kind code	B2
Filing date	Feb 18, 2019
Priority date	Aug 31, 2016
Publication date	Sep 29, 2020
Grant date	Sep 29, 2020

Abstract

When a film thickness of a second epitaxial film is measured, an infrared light is irradiated from a surface side of the second epitaxial film onto a base layer on which a first epitaxial film and the second epitaxial film are formed. A reflected light from an interface between the first epitaxial film and the base layer and a reflected light from a surface of the second epitaxial film are measured to obtain a two-layer film thickness, which is a total film thickness of the first epitaxial film and the second epitaxial film. The film thickness of the second epitaxial film is calculated by subtracting a one-layer film thickness, which is a film thickness of the first epitaxial film, from the two-layer film thickness.

First claim

What is claimed is:

1. A manufacturing method of a silicon carbide semiconductor device comprising:
preparing a structure in which a first epitaxial film having a film thickness of 5 μm to 14 μm is formed on a base layer made of silicon carbide;
irradiating an infrared light from a surface side of the first epitaxial film, and measuring a first film thickness, which is the film thickness of the first epitaxial film, by Fourier transform infrared spectroscopy based on a reflected light from an interface between the first epitaxial film and the base layer and a reflected light from a surface of the first epitaxial film;
forming a second epitaxial film having a film thickness of 0.5 μm to 2.0 μm on the first epitaxial film;
irradiating an infrared light from a surface side of the second epitaxial film, and measuring a second film thickness, which is a total film thickness of the first epitaxial film and the second epitaxial film, by Fourier transform infrared spectroscopy based on the reflected light from the interface between the first epitaxial film and the base layer and a reflected light from a surface of the second epitaxial film; and
calculating the film thickness of the second epitaxial film by subtracting the first film thickness from the second film thickness, and controlling the film thickness of the second epitaxial film.

2. The manufacturing method according to claim 1 , further comprising
forming an ion implantation layer on the first epitaxial film by ion implantation, wherein
the second epitaxial film is formed after forming the ion implantation layer.

3. The manufacturing method according to claim 1 , wherein
the preparing the structure in which the first epitaxial film is formed includes preparing a substrate of a first conductivity type or a second conductivity type as the base layer, and forming a drift layer of the first conductivity type having a lower impurity concentration than an impurity concentration of the substrate on the substrate as the first epitaxial film, and
the forming the second epitaxial film includes forming a base region of the second conductivity type on the drift layer as the second epitaxial film,
the manufacturing method further comprising:
forming a source region made of silicon carbide of the first conductivity type having a higher impurity concentration than the impurity concentration of the drift layer on an upper layer portion of the base region;
forming a trench gate structure including a gate trench provided deeper than the base region from a surface of the source region, a gate insulating film formed on an inner wall surface of the gate trench, and a gate electrode formed on the gate insulating film;
forming a source electrode electrically connected to the source region and the base region; and
forming a drain electrode on a rear surface side of the substrate.

4. The manufacturing method according to claim 3 , wherein
the forming the source region includes epitaxially growing the source region on the base region,
the manufacturing method further comprising:
irradiating an infrared light from a surface side of a third epitaxial film using the source region as the third epitaxial film, and measuring a third film thickness that is a total film thickness of the first epitaxial film, the second epitaxial film, and the third epitaxial film by Fourier transform infrared spectroscopy based on a reflected light from the interface between the first epitaxial film and the base layer and a reflected light from a surface of the third epitaxial film; and
calculating a film thickness of the third epitaxial film by subtracting the second film thickness from the third film thickness.

5. A manufacturing method of a silicon carbide semiconductor device comprising:
preparing a structure in which a first epitaxial film having a film thickness of 5 μm to 14 μm is formed on a base layer made of silicon carbide;
irradiating an infrared light from a surface side of the first epitaxial film, and measuring a first film thickness, which is the film thickness of the first epitaxial film, by Fourier transform infrared spectroscopy based on a reflected light from an interface between the first epitaxial film and the base layer and a reflected light from a surface of the first epitaxial film;
forming a second epitaxial film having a film thickness of 0.5 μm to 2.0 μm on the first epitaxial film;
irradiating an infrared light from a surface side of the second epitaxial film, and measuring a second film thickness, which is a total film thickness of the first epitaxial film and the second epitaxial film, by Fourier transform infrared spectroscopy based on the reflected light from the interface between the first epitaxial film and the base layer and a reflected light from a surface of the second epitaxial film;
calculating the film thickness of the second epitaxial film by subtracting the first film thickness from the second film thickness; and
removing the second epitaxial film by etching back by the film thickness that is calculated.

6. The manufacturing method according to claim 5 , further comprising
providing a trench in the first epitaxial film before growing the second epitaxial film, wherein
the growing the second epitaxial film includes burying the second epitaxial film in the trench, and
the removing the second epitaxial film by etching back includes leaving the second epitaxial film only in the trench by removing the second epitaxial film by etching back by the film thickness that is calculated.

7. The manufacturing method according to claim 6 , wherein
the preparing the structure in which the first epitaxial film is formed includes preparing a substrate of a first conductivity type or a second conductivity type as the base layer, and epitaxially growing a drift layer of the first conductivity type having a lower impurity concentration than an impurity concentration of the substrate, a base region of the second conductivity type, and a source region made of silicon carbide of the first conductivity type having a higher impurity concentration than the impurity concentration of the drift layer in order on the substrate as the first epitaxial layer,
the providing the trench includes providing the trench that penetrates through the base region from the source region and reaches the drift layer, and
the growing the second epitaxial layer includes epitaxially growing a second conductivity type layer as the second epitaxial film, and
the removing the second conductivity type layer includes leaving the second conductivity type layer in the trench to provide a deep layer of the second conductivity type,
the manufacturing method further comprising:
forming a trench gate structure including a gate trench deeper than the base region from the surface of the source region, a gate insulating film formed on an inner wall surface of the gate trench, and a gate electrode formed on the gate insulating film;
forming a source electrode electrically connected to the source region and the base region; and
forming a drain electrode over a rear surface side of the substrate.

Assignees

• Denso Corp
• Toyota Motor Co Ltd

Inventors

• Amano Akira
• SATOMURA Takayuki
• Takeuchi Yuichi
• Suzuki Katsumi
• Aoi Sachiko

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P74/23

  characterised by multiple measurements, corrections, marking or sorting processes · CPC title

• H10P30/204

  into Group IV semiconductors · CPC title

• H10P30/21

  of electrically active species · CPC title

• H10D62/8325

  Silicon carbide · CPC title