US-12625022-B2 - Semiconductor pressure sensor and manufacturing method therefor

Abstract

A semiconductor pressure sensor according to the present disclosure includes: a first silicon substrate; a first silicon oxide film provided on the first silicon substrate and forming a closed space together with the first silicon substrate; a second silicon substrate provided on the first silicon oxide film; a gauge resistor provided on a surface layer of a surface of the second silicon substrate opposite to a surface on which the first silicon oxide film is provided at a position overlapping with the closed space in a plan view; a first electrode electrically connected to one end of the gauge resistor; and a second electrode electrically connected to another end of the gauge resistor.

Inventors

• Kimitoshi Sato

Assignees

• MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date

20260512

Application Date

20210330

Priority Date

20200707

Claims (7)

1. 1 . A semiconductor pressure sensor comprising: a first silicon substrate; a first silicon oxide film provided on the first silicon substrate and forming a closed space together with the first silicon substrate; a second silicon substrate provided on the first silicon oxide film; a gauge resistor provided on a surface layer of a surface of the second silicon substrate opposite to a surface on which the first silicon oxide film is provided at a position overlapping with the closed space in a plan view; a first electrode electrically connected to one end of the gauge resistor; and a second electrode electrically connected to another end of the gauge resistor, wherein the first silicon oxide film includes: a thick film portion having one surface in contact with the first silicon substrate and another surface in contact with the second silicon substrate; and a first thin film portion having one surface facing the first silicon substrate across the closed space and another surface in contact with the second silicon substrate, such that the thick film portion and the first thin film portion are parts of the first silicon oxide film.
2. 2 . The semiconductor pressure sensor according to claim 1 , further comprising: a second silicon oxide film provided on the second silicon substrate; and a protective film provided on the second silicon oxide film, wherein the protective film has a first groove provided at a position overlapping with the closed space in a plan view.
3. 3 . The semiconductor pressure sensor according to claim 1 , wherein the second silicon substrate has a second groove provided in a surface opposite to the surface on which the first silicon oxide film is provided along an outer edge of the closed space in a plan view.
4. 4 . The semiconductor pressure sensor according to claim 1 , wherein the first silicon oxide film has an opening provided in a center of the first thin film portion.
5. 5 . The semiconductor pressure sensor according to claim 1 , wherein the first silicon oxide film includes a second thin film portion thicker than the first thin film portion in a center of the first thin film portion.
6. 6 . The semiconductor pressure sensor according to claim 1 , wherein the second silicon substrate has a third groove provided in the surface on which the first silicon oxide film is provided on an inner periphery of the closed space in a plan view.
7. 7 . The semiconductor pressure sensor according to claim 1 , wherein the second silicon substrate has a dimple provided in the surface on which the first silicon oxide film is provided in a center of the closed space in a plan view.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present disclosure relates to a diaphragm type semiconductor pressure sensor that measures a minute pressure, and a manufacturing method for the semiconductor pressure sensor. Description of the Background Art Conventionally, a technique relating to a diaphragm type semiconductor pressure sensor has been disclosed (see, for example, Japanese Patent Application Laid-Open No. 2015-145801). A semiconductor pressure sensor that detects a minute pressure needs to increase the area of a diaphragm and reduce the thickness in order to increase the detection sensitivity to a pressure change. For example, the area of the diaphragm is 3 mm square or less, and the thickness is 20 μm or less. In a conventional semiconductor pressure sensor, it is difficult to form or process a film on the back surface of the diaphragm. Further, in the conventional semiconductor pressure sensor, it is difficult to control the stress of the diaphragm because only a laminated film provided on a surface of a silicon substrate influences the stress characteristics of the diaphragm. Therefore, a minute pressure applied to the diaphragm is buried in the influence of the stress (deformation of the diaphragm) due to the laminated film, and the minute pressure cannot be detected accurately. SUMMARY An object of the present disclosure is to provide a semiconductor pressure sensor capable of accurately detecting a minute pressure and a manufacturing method therefor. According to the present disclosure, there is provided a semiconductor pressure sensor according to the present disclosure includes: a first silicon substrate; a first silicon oxide film provided on the first silicon substrate and forming a closed space together with the first silicon substrate; a second silicon substrate provided on the first silicon oxide film; a gauge resistor provided on a surface layer of a surface of the second silicon substrate opposite to a surface on which the first silicon oxide film is provided at a position overlapping with the closed space in a plan view; a first electrode electrically connected to one end of the gauge resistor; and a second electrode electrically connected to the other end of the gauge resistor. According to the present disclosure, the semiconductor pressure sensor includes: the first silicon oxide film provided on the first silicon substrate and forming the closed space together with the first silicon substrate; the second silicon substrate provided on the first silicon oxide film; the gauge resistor provided on the surface layer of the surface of the second silicon substrate opposite to the surface on which the first silicon oxide film is provided at the position overlapping with the closed space in a plan view; the first electrode electrically connected to one end of the gauge resistor; and the second electrode electrically connected to the other end of the gauge resistor. Thus, it is possible to accurately detect a minute pressure. These and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing an example of a configuration of a semiconductor pressure sensor according to a first preferred embodiment; FIG. 2 is a cross-sectional view taken along the line A1-A2 of FIG. 1; FIG. 3 is a cross-sectional view taken along the line B1-B2 of FIG. 1; FIG. 4 is a flowchart showing an example of a manufacturing process of the semiconductor pressure sensor according to the first preferred embodiment; FIG. 5 is a plan view for explaining a manufacturing process of the semiconductor pressure sensor according to the first preferred embodiment; FIG. 6 is a cross-sectional view taken along the line A1-A2 of FIG. 5; FIG. 7 is a cross-sectional view taken along the line B1-B2 of FIG. 5; FIG. 8 is a plan view for explaining a manufacturing process of the semiconductor pressure sensor according to the first preferred embodiment; FIG. 9 is a cross-sectional view taken along the line A1-A2 of FIG. 8; FIG. 10 is a plan view for explaining a manufacturing process of the semiconductor pressure sensor according to the first preferred embodiment; FIG. 11 is a cross-sectional view taken along the line A1-A2 of FIG. 10; FIG. 12 is a plan view for explaining a manufacturing process of the semiconductor pressure sensor according to the first preferred embodiment; FIG. 13 is a cross-sectional view taken along the line A1-A2 of FIG. 12; FIG. 14 is a cross-sectional view taken along the line B1-B2 of FIG. 12; FIG. 15 is a cross-sectional view taken along the line A1-A2 of FIG. 12; FIG. 16 is a cross-sectional view taken along the line A1-A2 of FIG. 12; FIG. 17 is a plan view for explaining a manufacturing process of the semiconductor pressure sensor according to the first preferred embodi