US 12,745,418 B2Granted

Semiconductor device and method of manufacturing semiconductor device

AssigneeFuji Electric Co., Ltd.

InventorsYasushi Niimura, Kazuya Yamaguchi

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Abstract

A semiconductor device has a semiconductor substrate of a first conductivity type; a drift layer of the first conductivity type; a base layer of a second conductivity type; an active region through which a main current flows and having source regions of the first conductivity type, trenches, gate insulating films, and gate electrodes; and a termination region surrounding a periphery of the active region. The termination region has a conductive film electrically connected to the gate electrode, a field oxide film that insulates the conductive film from the drift layer, and a contact hole that penetrates through the conductive film and reaches the field oxide film. The contact hole is embedded in the field oxide film such that a thickness of the field oxide film below the contact hole has is 54 nm to 85 nm thinner than a thickness of the field oxide film outside the contact hole.

Claims9

Dependent claims

A semiconductor device having

an active region through which a main current flows, and
a termination region surrounding a periphery of the active region in a plan view of the semiconductor device,
the semiconductor device comprising:
a semiconductor substrate of a first conductivity type, the semiconductor substrate having a main surface;
a drift layer of the first conductivity type, provided at the main surface of the semiconductor substrate;
a base layer of a second conductivity type, provided at a surface layer of the drift layer;
in the active region;
a source region of the first conductivity type, selectively provided in a surface layer of the base layer,
a trench reaching the drift layer from a surface of the source region, and
a gate electrode provided in the trench via a gate insulating film;
and
in the termination region;
a conductive film electrically connected to the gate electrode,
a field oxide film that insulates the conductive film and the drift layer from each other, and
a contact hole that penetrates through the conductive film and reaches the field oxide film, wherein
the contact hole is embedded in the field oxide film such that a thickness of the field oxide film below the contact hole is 15.4%-24.3% thinner than a thickness of the field oxide film outside the contact hole.

13 more elements

A method of manufacturing a semiconductor device having:

a semiconductor substrate of a first conductivity type and having a main surface;
a drift layer of the first conductivity type disposed on the main surface of the semiconductor substrate;
an active region provided at a front surface of the drift layer and through which a main current flows;
and a termination region surrounding a periphery of the active region, the method comprising:
forming a base layer of a second conductivity type at a surface layer of the drift layer;
forming a field oxide film at a surface of the drift layer in the termination region;
forming a trench reaching the drift layer from a surface of the base layer;
forming a gate insulating film in an entire area of an upper surface of the base layer;
depositing a polysilicon in an entire area of an upper surface of the gate insulating film;
etching the polysilicon, thereby, forming a gate electrode in the trench and a conductive film of the termination region;
selectively forming a source region of the first conductivity type in a surface layer of the base layer;
forming an interlayer insulating film in an entire area of an upper surface of the drift layer;
partially removing the interlayer insulating film, thereby, forming a first contact hole reaching the base layer in the active region and a second contact hole reaching the conductive film in the termination region;
performing a heat treatment, thereby, forming an oxide film in the first contact hole in the active region and in the second contact hole in the termination region;
performing etching, thereby, removing the oxide film;
and
forming a source electrode at the first contact hole in the active region and forming a gate metal electrode at the second contact hole in the termination region, wherein
the heat treatment is performed using a first gas containing oxygen only at a beginning of the heat treatment and during a period thereafter, the oxygen is cut.

15 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/495,467Filed 26 Oct 2023
Priority: JP 2022-1931011 Dec 2022
Published: US 2024/0186407 A16 Jun 2024
Granted: 22 Sep 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H10D 30/665
Vertical dmos [vdmos] fets: having edge termination structures
H10D 30/0297
Of vertical dmos [vdmos] fets: using recessing of the gate electrodes, e.g. to form trench gate electrodes
H10D 30/668
Vertical dmos [vdmos] fets: having trench gate electrodes, e.g. UMOS transistors
H10D 62/393
Semiconductor regions connected to electrodes not carrying current to be rectified, amplified or switched, e.g. channel regions: body regions of…