JPS633468A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To make it possible to adjust the pressure sensitivity of a diaphram, by forming a pressure-sensitivity adjusting thin film on the upper surface, or the lower surface, or both surfaces of the diaphragm of a semiconductor pressure sensor. CONSTITUTION:A diaphragm 5 is formed on a silicon chip 6 by anisotropic etching and the like. On the upper surface of the diaphragm, a protecting film 4 made of, e.g., an SiC film, is formed by a thin film technology such as a sputtering method. Pressure to be measured is introduced through a pressure introducing port 1. A voltage output is obtained from a diffused resistor, which is arranged on the diaphragm 5. The pressure sensitivity of the protecting film 4 is adjsuted by adjusting the thickness of the film. The protecting film 4 as the pressure-sensitivity adjusting thin film is formed on the upper surface of the diaphragm. However, the film 4 can be formed on the lower surface of the diaphragm 5 or can be formed on both upper and lower surfaces of the diaphragm 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor pressure sensor, and in particular to the structure of a diaphragm.

[Conventional technology]

Conventionally, the pressure sensitivity of this type of pressure sensor is determined by the film thickness of the sensing part of the diaphragm part, and it is known that the pressure sensitivity has a property that is inversely proportional to the square of the diaphragm thickness. has become an important point for this type of pressure sensor.

Conventionally, the technology for controlling diaphragm thickness has been to
There is a known technique in which etching is performed using anisotropic etching such as hydrazine from a P-type substrate while applying a positive electric field to the N-type layer using a substrate on which a shaped layer is epitaxially grown, and the etching stops at the PN junction interface. (Unexamined Japanese Patent Publication No. 59-152276).

Semiconductor pressure sensors integrate electronic circuits such as gauge resistors, which serve as sensitive elements, on the first main surface of a large number of unit cells arranged in a silicon wafer, and anisotropically etched, mechanically etched, etc. on a part of the second main surface. It is manufactured by forming a diaphragm by forming a dent through processing, etc., and then dividing it into unit cells, and making the unit cells into gougs.

[Problem that the invention seeks to solve]

The pressure sensitivity of the conventional semiconductor pressure sensor mentioned above is determined by the thickness of the N-type epitaxial layer, so in order to create a product group with different pressure sensitivities, it is necessary to prepare in advance substrates with different thicknesses of the N-type epitaxial layer. There was a drawback that there was.

An object of the present invention is to provide a semiconductor pressure sensor that allows adjustment of the pressure sensitivity of a diaphragm.

[Means for solving problems]

The semiconductor pressure sensor of the present invention is characterized in that a thin film for adjusting pressure sensitivity is formed on the upper surface, the lower surface, or both surfaces of the diaphragm.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

As shown in FIG. 1, a protective film 4 made of, for example, an SiC film is formed on the upper surface of a diaphragm of a silicon chip 6 on which a diaphragm 5 has been formed by anisotropic etching or the like by a thin film forming technique such as a sputtering method. The pressure to be measured is taken in through the pressure introduction port 1, and a voltage output is obtained by the diffusion resistor arranged on the diaphragm 5.

The pressure sensitivity of the protective film 4 is adjusted by adjusting the film thickness. Although the protective film 4 as a thin film for pressure sensitivity adjustment is formed on the upper surface of the diaphragm 5, it may be formed on the lower surface of the diaphragm 5 or on both the upper and lower surfaces of the diaphragm 5.

〔Effect of the invention〕

As explained above, the present invention has the effect of being able to adjust the pressure sensitivity of the diaphragm by forming a thin film on the diaphragm.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a semiconductor pressure sensor according to the present invention.

Claims (1)

[Claims] (1) A semiconductor pressure sensor characterized in that a thin film for adjusting pressure sensitivity is formed on the upper surface, the lower surface, or both surfaces of a diaphragm of the semiconductor pressure sensor.