JPH07113707A - Semiconductor multi-function sensor - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to enable high-accuracy measurement by thinning only the thin plate thickness of the differential pressure detection unit while keeping the thin portion of the static pressure detection unit constant. Another object of the present invention is to provide a multi-function sensor having different differential pressure measurement ranges. [Structure] Static pressure detection A semiconductor multi-function sensor having a static pressure detection unit in which the final shape of a thin-walled portion is formed by a crystal plane in which etching does not proceed by anisotropic etching. [Effect] By changing the etching time, a static pressure measurement range can be made constant without changing the pattern shape, and a semiconductor multi-function sensor compatible with different differential pressure measurement ranges can be manufactured. It has a great economic effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor composite function sensor, and more particularly to an etching type semiconductor composite function having a structure suitable for changing only the measurement range of a differential pressure detection unit without changing the measurement range of a static pressure detection unit. Regarding sensors.

[0002]

2. Description of the Related Art In a differential pressure transmitter used for flow rate measurement,
As a differential pressure sensor for converting a differential pressure into an electric signal, there is a semiconductor differential pressure sensor having a structure in which a gauge resistance is diffused and formed on a semiconductor substrate and a back surface is a thin-walled pressure-sensitive silicon diaphragm to detect a pressure difference applied to both sides.

Further, the differential pressure transmitter measures the temperature and the static pressure in order to correct the influence of the temperature change and the high pressure (static pressure) applied to both sides of the differential pressure sensor in the differential pressure output signal, and corrects them by an external circuit. The method is taken. Specifically, JP-A-60-6137
As described in Japanese Patent Publication, a semiconductor strain gauge group that is sensitive to differential pressure is provided on the thin portion of the differential pressure silicon diaphragm, and a semiconductor gauge group that is sensitive to temperature and static pressure are detected on the thin portion of the static pressure detection silicon diaphragm at the fixed portion. A semiconductor strain gauge group that is sensitive to is formed.

The differential pressure detecting thin portion and the static pressure detecting thin portion are simultaneously formed by anisotropic etching in an alkaline etching solution such as a potassium hydroxide solution. At this time, each of the detectors has the same etching depth and becomes a detector with a shape that obtains the optimum characteristics in the used measurement range, and is converted into an electric signal proportional to the differential pressure, temperature, and static pressure, and the external circuit is used. Corrects errors due to the temperature and static pressure of the differential pressure detection signal.

[0005]

In the differential pressure measurement, the pressure (static pressure) applied to the high pressure side and the low pressure side is used in a pressure range of several MPa to several tens MPa, which is several tens of times, depending on the process conditions. Since the semiconductor pressure sensor can perform sufficiently high-accuracy measurement with a single sensor in a measurement range of about several tens of times, an ordinary multi-function sensor can handle the static pressure detection unit with the same sensor.

However, the differential pressure measurement depends on the object to be measured.
The measurement range is different from 0 Pa to several MPa and 10,000 times or more. For this reason, a single sensor cannot cover the entire range, and several types of sensors with different measurement ranges are required. For these sensors, it is necessary to form a thin plate thickness corresponding to the differential pressure measurement range.

In the multi-function sensor in which the thin portion is formed by anisotropic etching, the differential pressure thin portion and the static pressure thin portion are formed at the same time, so the differential pressure thin portion and the static pressure thin portion have the same plate thickness. However, it is difficult to change the plate thickness only for the differential pressure thin section by changing the differential pressure measurement range.When manufacturing differential pressure detection sections with different differential pressure measurement ranges, change the thin section area of the static pressure detection section. Since it is necessary to simply change the thickness of the thin portion, it was a major obstacle in production.

The present invention solves the above-mentioned obstacles, and enables high-precision measurement by thinning only the thin plate thickness of the differential pressure detecting unit while keeping the thin portion of the static pressure detecting unit constant. Another object of the present invention is to provide a multi-function sensor having different differential pressure measurement ranges.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a differential pressure detecting portion comprising a differential pressure detecting thin portion and a semiconductor strain gauge resistance is provided on a semiconductor substrate, and a peripheral fixing portion comprises a V-shaped thin hole portion and a semiconductor strain gauge resistance. It is composed of a static pressure detection unit, and in the state where the static pressure detection thin wall portion shape is kept constant, only the differential pressure detection thin wall portion shape is etched, and only the differential pressure measurement range can be changed.

[0010]

A semiconductor multi-function sensor using a semiconductor silicon single crystal substrate having a crystal plane (100) has a semiconductor strain gauge resistance on one side and a strain-sensitive thin portion for detecting a differential pressure on the other side and a static pressure detecting for static pressure detection. The strain-sensitive thin portion is formed by anisotropic etching with an alkaline solution such as an aqueous potassium hydroxide solution.

In anisotropic etching, the etching rate greatly differs depending on the crystal plane, and etching in the <111> axis direction does not proceed. Therefore, (1
11) When the surface is exposed, etching of the surface stops in that state, and thereafter, the shape is maintained regardless of the etching time.

The static pressure detecting thin wall portion is formed into a shape of a quadrangular pyramid hole whose etching exposed surface is the entire surface (111) to form an optimum strain-sensitive portion. In subsequent etching, only the differential pressure thin wall portion is etched. Is progressing, and sensors of various differential pressure measuring ranges having optimum differential pressure sensitivity can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS.

FIG. 1 is a top view of an embodiment showing the principle configuration of the multi-function sensor of the present invention, and FIG. 2 is a vertical sectional view of FIG.

In FIGS. 1 and 2, 1 is a crystal plane (100)
Silicon single crystal sensor substrate (hereinafter referred to as sensor substrate)
The fixed thick portion 12 is airtightly fixed to the fixed base 2.

The central portion of the sensor substrate 1 is deformed in accordance with the pressure difference applied to both surfaces, that is, the differential pressure. On the thin portion 11, the differential pressure detecting semiconductor for converting the deformation into an electric signal. The strain gauge group 111 is formed by the diffusion method. Further, a temperature detecting semiconductor gauge 121 for converting a temperature change into an electric signal is formed in a part of the outer peripheral fixed thick portion 12 of the sensor substrate 1 by the same diffusion method as the differential pressure detecting semiconductor strain gauge. Further, a static pressure thin portion 13 is formed on the other part of the outer peripheral fixing portion 12 of the sensor substrate 1 by a quadrangular pyramid hole having a thin surface of four <111> crystal planes. Further, the semiconductor strain gauge 131 for static pressure detection is formed by the same diffusion method as the differential pressure and temperature detection gauge.

The thin portion 11 for detecting the differential pressure and the thin portion 13 for detecting the static pressure are simultaneously formed in the aqueous potassium hydroxide solution by anisotropic etching.

The static pressure detection thin portion 13 has four side openings parallel to the <110> crystal axis, and the etching surface is a quadrangular pyramid hole shape in which all the (111) crystal faces are formed, and the progress of etching is stopped. Formed in a thin shape with a square pyramid hole for optimum performance. As a result, after that, only the differential pressure detecting thin portion 11 is etched, and the differential pressure detecting thin portion 11 having optimum performance for the required differential pressure measuring range is obtained.

According to the above-described embodiment of the present invention, even if the anisotropic etching time is extended, the dimension of the static pressure detecting thin portion does not change. Therefore, only the differential pressure thin portion can be changed. It is possible to easily obtain a highly accurate semiconductor compound function sensor of various differential pressure measurement ranges by changing only the etching time without changing.

[0020]

According to the present invention, by changing the etching time, it is possible to change the plate thickness of the thin portion of the differential pressure detecting portion without changing the shape of the thin portion of the static pressure detecting portion. Without this, it is possible to easily manufacture a semiconductor multi-function sensor that is different only in the differential pressure measurement range, which is a great economical advantage.

[Brief description of drawings]

FIG. 1 is a top view of a semiconductor multi-function sensor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon single crystal sensor substrate, 2 ... Fixing base, 11 ... Differential pressure detection thin part, 12 ... Perimeter fixed thick part, 13 ... Static pressure detection thin part, 111 ... Differential pressure detection semiconductor strain gauge, 121
… Temperature detection semiconductor gauge, 131… Static pressure detection semiconductor strain gauge.

Claims (3)

[Claims] 1. A semiconductor function sensor having a differential pressure detector and a static pressure detector on a semiconductor substrate, wherein the static pressure detector is a V-shaped thin portion. 2. The semiconductor substrate according to claim 1, which is a semiconductor silicon single crystal substrate having a (100) crystal plane, wherein the opening of the V-shaped thin portion of the static pressure detection portion has a <110> crystal axis on all sides. And the processed hole wall surface is (11
1) A semiconductor compound function sensor characterized by having a crystal plane. 3. The differential pressure detection unit and the static pressure detection unit according to claim 1,
A semiconductor multi-function sensor characterized by simultaneously forming a thin portion by anisotropic etching.