US-12628405-B2 - Semiconductor device, method for manufacturing semiconductor device, inverter circuit, drive device, vehicle, and elevator

Abstract

A semiconductor device according to an embodiment includes a silicon carbide layer, a silicon oxide layer having a peak frequency of a longitudinal wave optical mode of 1245 cm −1 or more at a position 0.5 nm away from the silicon carbide layer, and a region located between the silicon carbide layer and the silicon oxide layer and having a nitrogen concentration of 1×10 21 cm −3 or more. The concentration distribution of nitrogen in the silicon carbide layer, the silicon oxide layer, and the region has a peak in the region.

Inventors

• Tatsuo Shimizu

Assignees

• KABUSHIKI KAISHA TOSHIBA

Dates

Publication Date

20260512

Application Date

20230302

Priority Date

20220912

Claims (12)

1. 1 . A semiconductor device comprising: a silicon carbide layer; a silicon oxide layer having a peak frequency of a longitudinal wave optical mode of 1245 cm −1 or more at a position 0.5 nm away from the silicon carbide layer; and a region located between the silicon carbide layer and the silicon oxide layer and having a nitrogen concentration of 1×10 21 cm −3 or more, wherein a concentration distribution of nitrogen in the silicon carbide layer, the silicon oxide layer, and the region has a peak in the region, and a concentration of nitrogen at a first position 1 nm away from the peak toward the silicon oxide layer is 1×10 18 cm −3 or less, and a concentration of carbon at the first position is 1×10 18 cm −3 or less.
2. 2 . A semiconductor device comprising: a silicon carbide layer; a silicon oxide layer having a peak frequency of a longitudinal wave optical mode of 1245 cm −1 or more at a position 0.5 nm away from the silicon carbide layer; and a region located between the silicon carbide layer and the silicon oxide layer and having a nitrogen concentration of 1×10 21 cm −3 or more, wherein a concentration distribution of nitrogen in the silicon carbide layer, the silicon oxide layer, and the region has a peak in the region, and a concentration of nitrogen at a second position 1 nm away from the peak toward the silicon carbide layer is 1×10 18 cm −3 or less.
3. 3 . The semiconductor device according to claim 1 , wherein the peak has a nitrogen concentration of 1×10 22 cm −3 or more.
4. 4 . The semiconductor device according to claim 1 , further comprising a gate electrode interposing the silicon oxide layer with the silicon carbide layer.
5. 5 . An inverter circuit comprising the semiconductor device according to claim 1 .
6. 6 . A drive device comprising the semiconductor device according to claim 1 .
7. 7 . A vehicle comprising the semiconductor device according to claim 1 .
8. 8 . An elevator comprising the semiconductor device according to claim 1 .
9. 9 . The semiconductor device according to claim 2 , wherein the peak has a nitrogen concentration of 1×10 22 cm −3 or more.
10. 10 . The semiconductor device according to claim 2 , further comprising a gate electrode interposing the silicon oxide layer with the silicon carbide layer.
11. 11 . An inverter circuit comprising the semiconductor device according to claim 2 .
12. 12 . A drive device comprising the semiconductor device according to claim 2 .

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2022-144470, filed on Sep. 12, 2022, the entire contents of which are incorporated herein by reference. Embodiments described herein relate generally to a semiconductor device, a method for manufacturing a semiconductor device, an inverter circuit, a drive device, a vehicle, and an elevator. BACKGROUND Silicon carbide (SiC) is expected as a material for next-generation semiconductor devices. As compared with silicon (Si), silicon carbide has excellent physical properties such as a band gap of three times, a breakdown field strength of about 10 times, and a thermal conductivity of about three times. By utilizing this characteristic, a semiconductor device capable of operating at a low loss and a high temperature can be realized. For example, when a metal oxide semiconductor field effect transistor (MOSFET) is formed using silicon carbide, there is a problem that carrier mobility decreases. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of a semiconductor device according to a first embodiment; FIG. 2 is a diagram illustrating a crystal structure of a SiC semiconductor; FIG. 3 is a diagram illustrating a peak frequency of a longitudinal wave optical mode in a gate insulating layer of the semiconductor device according to the first embodiment; FIG. 4 is a diagram illustrating an element concentration distribution of the semiconductor device according to the first embodiment; FIG. 5 is a process flow diagram of a method for manufacturing the semiconductor device according to the first embodiment; FIG. 6 is a process flow diagram of a method for manufacturing a semiconductor device according to a comparative example; FIG. 7 is a diagram illustrating a peak frequency of a longitudinal wave optical mode in a gate insulating layer of the semiconductor device according to the comparative example; FIG. 8 is a diagram illustrating an element concentration distribution of the semiconductor device according to the comparative example; FIG. 9 is an explanatory diagram of defects in the gate insulating layer according to the comparative example; FIG. 10 is a schematic cross-sectional view of a semiconductor device according to a second embodiment; FIG. 11 is a schematic cross-sectional view of a semiconductor device according to a third embodiment; FIG. 12 is a schematic diagram of a drive device according to a fourth embodiment; FIG. 13 is a schematic diagram of a vehicle according to a fifth embodiment; FIG. 14 is a schematic diagram of a vehicle according to a sixth embodiment; and FIG. 15 is a schematic diagram of an elevator according to a seventh embodiment. DETAILED DESCRIPTION A semiconductor device according to an embodiment includes: a silicon carbide layer; a silicon oxide layer having a peak frequency of a longitudinal wave optical mode of 1245 cm−1 or more at a position 0.5 nm away from the silicon carbide layer; and a region located between the silicon carbide layer and the silicon oxide layer and having a nitrogen concentration of 1×1021 cm−3 or more, in which a concentration distribution of nitrogen in the silicon carbide layer, the silicon oxide layer, and the region has a peak in the region. Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same or similar members and the like are denoted by the same reference numerals, and the description of the members and the like once described is appropriately omitted. In the following description, when there are notations of n+, n, and n−, and p+, p, and p−, the relative level of the impurity concentration in each conductivity type is represented. That is, n+ indicates that the n-type impurity concentration is relatively higher than n, and n− indicates that the n-type impurity concentration is relatively lower than n. In addition, p+ indicates that the p-type impurity concentration is relatively higher than p, and p− indicates that the p-type impurity concentration is relatively lower than p. In addition, an n+-type and an n−-type may be simply referred to as an n-type, and a p+-type and a p−-type may be simply referred to as a p-type. Unless otherwise specified, the impurity concentration of each region is represented by, for example, the value of the impurity concentration in the central portion of each region. The impurity concentration can be measured by, for example, secondary ion mass spectrometry (SIMS). The relative level of the impurity concentration can also be determined from the level of the carrier concentration obtained by, for example, scanning capacitance microscopy (SCM). The distance such as the width and depth of the impurity region can be obtained by, for example, SIMS. Also, the distance such as the width and depth of the impurity region can be obtained from, for example, the SCM image. The d