US-12628392-B2 - Switching element

US12628392B2US 12628392 B2US12628392 B2US 12628392B2US-12628392-B2

Abstract

A switching element includes a gate electrode and a source electrode disposed in each of trenches provided in a semiconductor substrate. A longitudinal direction of the trench is defined as a first direction, and the trenches are spaced from each other in a second direction intersecting the first direction. Each of the trenches extends in the first direction while being displaced in the second direction so as to satisfy that an inter-trench region between the adjacent trenches has narrow portions and wide portions alternately arranged in the first direction and alternately arranged in the second direction via the trenches. A source region is distributed across the narrow portion and the wide portion, and is in contact with the source electrode in the wide portion.

Inventors

Jun Saito

Assignees

DENSO CORPORATION
TOYOTA JIDOSHA KABUSHIKI KAISHA
MIRISE Technologies Corporation

Dates

Publication Date: 20260512
Application Date: 20230927
Priority Date: 20221006

Claims (8)

1 . A switching element comprising: a semiconductor substrate; a plurality of trenches on an upper surface of the semiconductor substrate; a gate insulating film covering an inner surface of each of the trenches; a gate electrode disposed in each of the trenches and insulated from the semiconductor substrate by the gate insulating film; and a source electrode on the upper surface of the semiconductor substrate, wherein the plurality of trenches is arranged on the upper surface such that a longitudinal direction of each of the trenches is defined as a first direction, the plurality of trenches is arranged on the upper surface and spaced from each other in a second direction intersecting the first direction, each of the trenches extends in the first direction while being displaced in the second direction on the upper surface so as to meet a first condition that an inter-trench region which is a semiconductor region defined between the trenches adjacent to each other has a plurality of narrow portions and a plurality of wide portions wider in the second direction than the narrow portion, and a second condition that the narrow portions and the wide portions are alternately arranged in the first direction, on the upper surface, and the narrow portions and the wide portions are alternately arranged in the second direction via the trenches, the semiconductor substrate includes: an n-type source region disposed in the inter-trench region over the narrow portion and the wide portion, in contact with the source electrode in the wide portion, and in contact with the gate insulating film in the narrow portion; a p-type body region disposed in the inter-trench region and in contact with the gate insulating film on a lower side of the source region in the narrow portion; and an n-type drift region distributed from the narrow portion to a region below the plurality of trenches and in contact with the gate insulating film on a lower side of the body region in the narrow portion.
2 . The switching element according to claim 1 , wherein the body region is distributed over the narrow portion and the wide portion, and is located below the source region in the wide portion, and the drift region is distributed over a lower part of the wide portion and a lower part of the narrow portion.
3 . The switching element according to claim 2 , wherein the semiconductor substrate includes a p-type electric field relaxation region in contact with the body region and in contact with the gate insulating film at a corner portion between a side surface of the trench adjacent to the wide portion and a bottom surface of the trench.
4 . The switching element according to claim 1 , wherein a width of the inter-trench region in the second direction decreases from the wide portion toward the narrow portion at a boundary portion between the narrow portion and the wide portion.
5 . The switching element according to claim 1 , wherein a connection trench is provided on the upper surface of the semiconductor substrate to connect the trenches through the narrow portion.
6 . The switching element according to claim 1 , wherein a width of the narrow portion in the second direction decreases from the wide portion toward a central part of the narrow portion, in each of the narrow portions, and the trenches on both sides of the narrow portion are connected to each other at the central part of the narrow portion.
7 . The switching element according to claim 1 , wherein the source region is in contact with the source electrode in each of the narrow portions.
8 . The switching element according to claim 1 , wherein the body region is in contact with the source electrode in each of the wide portions.

Description

CROSS REFERENCE TO RELATED APPLICATION This application is based on Japanese Patent Application No. 2022-161714 filed on Oct. 6, 2022, the disclosure of which is incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a switching element. BACKGROUND A switching element has trenches, and an interval is defined between the trenches. A gate electrode and a gate insulating film are disposed in each of the trenches. An n-type source region and a p-type body region are provided between the trenches. The source region is in contact with the gate insulating film at an upper end of each trench. The source region is in contact with a source electrode provided on the surface of the semiconductor substrate. The body region is in contact with the gate insulating film on the lower side of the source region. An n-type drift region is provided below the body region. SUMMARY A switching element includes: a semiconductor substrate; trenches provided on an upper surface of the semiconductor substrate; a gate insulating film covering an inner surface of each of the trenches; a gate electrode disposed in each of the trenches and insulated from the semiconductor substrate by the gate insulating film; and a source electrode provided on the upper surface of the semiconductor substrate. The trenches are arranged on the upper surface such that a longitudinal direction of each of the trenches is a first direction. The trenches are arranged on the upper surface and spaced from each other in a second direction intersecting the first direction. Each of the trenches extends in the first direction while being displaced in the second direction on the upper surface so as to meet a first condition that each inter-trench region which is a semiconductor region defined between the trenches adjacent to each other has narrow portions and wide portions wider in the second direction than the narrow portions, and a second condition that the narrow portions and the wide portions are alternately arranged along the first direction, on the upper surface, and the narrow portions and the wide portions are alternately arranged along the second direction via the trenches. The semiconductor substrate includes: an n-type source region disposed in each of the inter-trench regions over the narrow portion and the wide portion, in contact with the source electrode in the wide portion, and in contact with the gate insulating film in the narrow portion; a p-type body region disposed in each of the inter-trench regions and in contact with the gate insulating film on a lower side of the source region in the narrow portion; and an n-type drift region distributed from inside of each narrow portion to a region below the trenches and is in contact with the gate insulating film on the lower side of the body region in the narrow portion. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective and cross-sectional view illustrating a switching element according to a first embodiment. FIG. 2 is a cross-sectional view illustrating the switching element according to the first embodiment taken along the x direction. FIG. 3 is a cross-sectional view illustrating the switching element according to the first embodiment taken along the y direction. FIG. 4 is a plan view showing arrangement of trenches on the upper surface of the switching element according to the first embodiment. FIG. 5 is a cross-sectional view illustrating a switching element according to a first modification of the first embodiment taken along the x direction. FIG. 6 is a cross-sectional view illustrating a switching element according to a second modification of the first embodiment taken along the x direction. FIG. 7 is a plan view showing arrangement of trenches on the upper surface of a switching element according to a second embodiment. FIG. 8 is a plan view showing arrangement of trenches on the upper surface of a switching element according to a third embodiment. FIG. 9 is an explanatory view of a step of forming a trench in the switching element of the third embodiment. FIG. 10 is a plan view showing arrangement of trenches on the upper surface of a switching element according to a fourth embodiment. FIG. 11 is a plan view illustrating arrangement of trenches on an upper surface of a switching element according to a modification of the fourth embodiment. FIG. 12 is a plan view illustrating arrangement of trenches in a comparative example. DETAILED DESCRIPTION A switching element has trenches arranged at intervals. A gate electrode and a gate insulating film are disposed in each of the trenches. An n-type source region and a p-type body region are provided between the trenches. The source region is in contact with the gate insulating film at an upper end of each trench. The source region is in contact with a source electrode provided on the surface of the semiconductor substrate. The body region is in contact with the gate insulating film on the lower side of the source region. An