JPS62109370A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To reduce the irregularity and nonlinearity of a resistance between gauge elements by disposing the gauge elements tangentially and radially on a diaphragm in the vicinity. CONSTITUTION:A pair of gauges 2, 2' made of amorphous semiconductor are formed tangentially of a circle having a radius ra at the center O of a diaphragm 1 formed of a glass, stainless steel thin plate or an organic film as a center and gauge elements 3, 3' made of amorphous semiconductor are formed radially of the circle having a radius rb at the center O as a center at a suitable interval. The elements 2, 2', 3, 3' are disposed on the circles of the radii rb, ra to measure a pressure applied to the diaphragm 1. Since the elements 2, 2', 3, 3' are disposed at extremely near positions, the irregularity and the nonlinearity of the resistance value between the gauges 2, 2', 3, 3' can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a pressure sensor using an amorphous semiconductor as a gauge element.

Conventional technology Conventionally, this type of pressure sensor requires that the gauge element be epitaxially grown on a single crystal substrate, and that the diaphragm α, which is a single crystal substrate, is used to improve the sensitivity of the sensor and reduce nonlinearity. Gauge element A, A
', B, and B' must be arranged as shown in Fig. 2 (4) or Fig. 2 (b). However, in the case of the arrangement shown in Figure 2 (a), the distance between gauge elements A and A', and the distance between gauge elements A and A' and B and B' in the arrangement shown in Figure 2 (portion 1), respectively. ±7~ within the remote location, Ueno
There was a problem that the variation in each resistance value became large, such as variation in the numerical coefficient even within the chip.

In order to improve the above-mentioned defects, a semiconductor pressure sensor was developed in Japanese Patent Laid-Open No. 56-14 in which the variation in resistance value was reduced by forming the gauge element into an intertwined meandering pattern.
This is proposed in Publication No. 0669 and the like.

Problems to be Solved by the Invention However, even with the above-mentioned conventional devices, it is difficult to minimize variations in resistance values and nonlinearity for the following reasons.

A uniform pressure is uniformly applied to the diaphragm α of the semiconductor pressure sensor, and the stress in the tangential direction is as shown in Fig. 1 of the third garden.

Also, the next gauge element A + A provided on the diaphragm α
, B e The change in resistance of W is expressed as
πt σt (Gauge person)・・・・・・(1) Peni −
πt 6t + πr σt (Gauge B)...
...(2) (σr is the stress in the radial direction, σt is the pressure in the tangential direction (see port 1), πt, πr are 8i
It is expressed as the piezoresistance coefficient of the semiconductor. In the case of single crystal Si, normally πr >> πt, so Equation (1) and Equation (21 are entered) φπ7σ7 ...... (3) 10, medium π7σt ...... (4) The change is proportional to the stress.

However, equations (3) and (4) are approximate values, and near the center of the diaphragm where σt is large, equations (3) and (4)
Since the approximation of is deviated, nonlinear effects occur. It is advantageous to place the gauge A near the circumference where σ7〉σt.

Since the distance between A' and A' is far apart, the fluctuation in resistance value is still not resolved.

This invention was made for the purpose of improving the above-mentioned problems.

Means for Solving the Problem and Working Diaphragm Gauge elements made of amorphous semiconductors are placed close to each other on the diaphragm in the tangential direction and radial direction of a circle centered on the center O of the diaphragm. A semiconductor pressure sensor that reduces resistance variation and nonlinearity between each gauge element.

Example This invention will be described in detail with reference to an embodiment shown in FIG.

In the figure, 1 is a diaphragm formed on glass, a thin stainless steel plate, an organic film, etc. On a circle of radius rα centered on the center 0 of this diaphragm 1, a pair of amorphous semiconductors are arranged in the tangential direction of the circle. gauge 2
Gauge elements 3 and 3' made of amorphous semiconductor are formed at appropriate intervals in the radial direction of the circle on a circle having radius rb centered on the center 0.

Since amorphous semiconductors can be deposited regardless of the type of substrate 1, they can be easily deposited on glass, stainless steel, organic films, etc., and their arrangement on substrate I is not limited by crystal axes. , the arrangement of the above embodiments is also easy.

In the case of amorphous semiconductors, there is a piezoresistance effect similar to single crystal semiconductors, and this is determined only by the direction of current and stress. Therefore, the amorphous semiconductor is used as the gauge element 2.
, 2', 3, and 3', and by using the arrangement as in the above embodiment, the object of the present invention can be achieved.

Next, the reason will be explained. The stress σr in the radial direction and the stress σt in the tangential direction with respect to the pressure applied to the diaphragm 1 during use are expressed by the following equations.

σr−”/6)2(t l +U) α2− (3+U)
r2)(It-"/B12C(1+U) a'-+1
+3σ) r2] P: applied pressure, A: diaphragm thickness ■: Boisson's ratio α: 〃 radius Therefore, the gauge elements 2.2', 3, and 3' are placed on the circle with nine radius rb # rα. In particular, υ makes it possible to measure the pressure exerted on the diaphragm 1, and since each gauge element 2.2', 3.3' is arranged very close to each other, the gauge elements 2.2', 3.3'3.3' It becomes possible to reduce variations in resistance values and non-linearity between them.

Effects of the Invention As described in detail above, this invention arranges gauge elements close to each other in the tangential and radial directions on the diaphragm, thereby reducing variations in resistance values and nonlinearity between each gauge element. In addition, since it is only necessary to change the arrangement of the gauge elements, it can be implemented at low cost. Furthermore, by using an amorphous semiconductor for the gauge element, a similar material can be used for the rainbow substrate, and a pressure sensor suitable for the purpose can be easily obtained.

[Brief explanation of drawings]

Figure 1 is a layout diagram showing an embodiment of the invention; Figure 2 H)
, (b) and FIG. 1 diaphragm, 2.2' and 3.3' are gauge elements.

Claims (1)

[Claims] On the diaphragm 1, gauge elements 2, 2', 3, 3' made of amorphous semiconductor are arranged close to each other in the tangential direction and radial direction of a circle centered on the center O of the diaphragm 1.
A semiconductor pressure sensor made by arranging.