JPS62118259A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To obtain an acceleration sensor which exactly senses the acceleration component in only one direction by providing plural deflecting parts to a semiconductor acceleration sensor consisting of a weight part and deflecting parts. CONSTITUTION:The (100) face of an Si substrate is etched by an alkaline etching soln. to expose the (111) face. The weight part which moves when applied with an acceleration and the deflecting parts 4, 5 which generate deflecting stress according to the movement of the weight part and are formed like leaves. An impurity such as B or P is diffused on the deflecting parts 4, 5 to form resistors 6, 7. Since the two deflecting parts 4, 5 are disposed, the sensor has rigidity with respect to the y direction and the twist direction and is movable only in the z direction.

Description

[Detailed Description of the Invention] [Summary] In a semiconductor acceleration sensor consisting of a weight portion and a flexible portion, a plurality of flexible portions are provided to maintain rigidity and accurately sense acceleration.

[Industrial application field]

The present invention relates to an acceleration sensor, and particularly to an acceleration sensor that accurately senses acceleration in a certain direction.

[Conventional technology]

As shown in FIG. 2, a conventional acceleration sensor has a (100) plane of a silicon substrate as its main surface, and has a portion that senses acceleration in two directions, for example.

Assuming that the mass of the weight portion 1 is m, in FIG. 2, when the sensor receives acceleration α in two directions, a force F=mα is applied to the weight portion 1, and as a result, the flexure portion 2, which has a thin plate, is bent. The resistance value of the resistor 3 changes due to the piezoresistance effect expressed by the following equation from the stress T generated thereby.

1Δρ1=ρ1π11T1 Δρ: Amount of change in resistivity due to stress ρ: Resistivity without strain π: Piezoresistance coefficient A semiconductor acceleration sensor detects acceleration from this change in resistance value. As shown in FIG. 2, the conventional semiconductor acceleration sensor consists of a weight part 1 and a thin flexible part 2 that is linked to the moving part 1. The flexible part 2 has a sales promotion resistor 3 formed on its surface. It senses acceleration and is miniaturized to improve sensitivity and accuracy.

[Problem that the invention seeks to solve]

The flexible portion 2 shown in FIG. 2 may be deflected not only in the two directions of acceleration measurement, but also in the y and torsion directions. Therefore, resistance changes caused by deflection in the y direction and torsional direction and resistance caused by deflection in two directions coexist, creating a problem in accurately sensing acceleration components in only two directions.

An object of the present invention is to provide an acceleration sensor that accurately senses acceleration components in only one direction.

[Means for solving problems]

The above-mentioned problem is solved according to the present invention, which includes a weight portion formed by processing a semiconductor substrate and a thin flexible portion that moves in conjunction with the weight portion and supports the weight portion. The problem is solved by an acceleration sensor characterized in that a plurality of bending parts are provided in the sensor.

[For production]

That is, in the present invention, an acceleration sensor is provided with a plurality of flexible parts that interlock with and support the weight part, thereby providing rigidity in, for example, the lateral and torsional directions, and accurately sensing only the vertical direction.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a perspective view for explaining one embodiment of the present invention. In FIG. 1, the silicon substrate (1
By etching the 00) surface with an alkaline etching solution, the 011) surface is exposed and a weight portion 1 that moves when acceleration is applied, and thinned flexible portions 4 and 5 where deflection stress is generated by the movement of the weight portion 1 are formed. ing. Resistors 6.7 formed by diffusing impurities such as boron or phosphorus are shown on the bent portions 4.5, respectively.

As a result of the two flexible parts 4 and 5, it has rigidity in the y direction and the torsional direction, and is movable in only two directions. Note that 8 is a bonding pad that serves as a terminal for measuring the resistance value.

〔Effect of the invention〕

According to the present invention, it is possible to create an acceleration sensor that has a flexible portion that deforms in only one direction, making it possible to detect acceleration with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a perspective view for explaining one embodiment of the present invention, and FIG. 2 is a perspective view showing a conventional acceleration sensor. l... Weight part, 2.4.5... Deflection part,
3.6.7... Diffusion resistance, 8... Bonding pad that serves as a terminal for measuring resistance value. Figure 1 Conventional example Figure 2

Claims (1)

[Claims] 1. An acceleration sensor comprising a weight portion formed by processing a semiconductor substrate and a thin flexible portion that moves in conjunction with the weight portion and supports the weight portion, and has a resistance in the flexible portion, wherein a plurality of the flexible portions are provided. An acceleration sensor characterized by: