JPH04184232A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To obtain a sensor with a high sensitivity by arranging a plurality of diaphragms varied in thickness on one surface of a chip while a strain gauge is provided on the other surface thereof corresponding thereto. CONSTITUTION:Thickness of first and second diaphragms are represented by h1 and h2 and radii of first and second strain gauges 11 and 12 by a1 and a2 and a relationship therebetween is expressed by a1/h1=a2/h2. Then, when a pressure is applied to the diaphragms 13 and 14, they are deformed and an equal voltage is obtained form the strain gauges 11 and 12 per pressure. Thus, output is doubled for each one pressure thereby achieving a higher sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a semiconductor pressure sensor in which a diaphragm is formed on one side of a chip and a strain gauge is provided on the other side of the chip in correspondence with the diaphragm. It is related to sensors.

[Prior Art] Fig. 3 is a plan view of a chip of a conventional semiconductor pressure sensor. The strain gauge (3) provided along the chip (1) is a diaphragm that is a pressure receiving part located in the center of the chip (1).

In the above semiconductor pressure sensor, the diaphragm (3
), the diaphragm (3) deforms, the electrical resistance of the strain gauge (2) changes along with the deformation, and the change in resistance is output as a voltage.

[Problems to be Solved by the Invention] Since the conventional semiconductor pressure sensor has been refined as described above, it has a problem that it has only one output for one pressure, and has poor sensitivity to minute pressure.

This invention was made in order to solve such problems, and an object of the present invention is to provide a highly sensitive semiconductor pressure sensor that can obtain multiple times more output per pressure than conventional ones. shall be.

[Means for Solving the Problems] A semiconductor pressure sensor according to the present invention includes a plurality of diaphragms having different thicknesses formed on one surface of a chip, and a plurality of diaphragms having different thicknesses formed on the other surface of the chip, respectively corresponding to these diaphragms. It is equipped with strain gauges.

[Function] In the semiconductor pressure sensor of the present invention, when pressure is applied to the diaphragm, the plurality of diaphragms deform, and a plurality of outputs are obtained from each strain gauge for one pressure.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a side sectional view of FIG. A first strain gauge (12) is provided along the circumference, and a second strain gauge (12) is provided along the circumference inside the first strain gauge (11).
(13) is a first diaphragm formed on the back surface of the chip (10) corresponding to the first strain gauge (11), (14) is a second diaphragm formed on the back surface of the chip (10).
This is a second diaphragm formed to correspond to the strain gauge (12). Then, the first diaphragm (13
) and the thickness of the second diaphragm (14) h l, h
2 and the radius at, a of the first strain gauge (11) and the second strain gauge (12) is shown by the following equation.

a, a2 1h 2 In the semiconductor pressure sensor refined as above,
When pressure is applied to the first diaphragm (13) and second diaphragm (14), which are pressure receiving parts, the first diaphragm (13) and the second diaphragm (14) deform, and the Equal voltages are obtained from the first strain gauge (11) and the second strain gauge (12), that is, two equal outputs are obtained for one pressure, the output is doubled, and the sensitivity is increased accordingly. will improve.

In addition, in the above embodiment, a semiconductor pressure sensor having a first diaphragm (13) and a second diaphragm (14) has been described, but a semiconductor pressure sensor having three or more diaphragms and a corresponding strain gauge may also be used. In that case, the sensitivity of the semiconductor pressure sensor increases depending on the number of diaphragms.

[Effects of the Invention] As explained above, according to the semiconductor pressure sensor of the present invention, a plurality of diaphragms with different thicknesses are formed on one surface of the chip, and these diaphragms are formed on the other surface of the chip. By providing strain gauges corresponding to each, it is possible to obtain an output that is several times as large as the negative pressure, which has the effect of improving sensitivity even to minute pressures.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a side sectional view of FIG. 1, FIG. 3 is a plan view showing an example of a conventional semiconductor pressure sensor, and FIG. FIG. In the figure, (10) is a chip, (11) is a first strain gauge, (12) is a second strain gauge, (13) is a first diaphragm, and (14) is a second diaphragm. Note that the same reference numerals in each mouth indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A semiconductor pressure sensor comprising: a plurality of diaphragms having different thicknesses formed on one surface of a chip; and strain gauges provided on the other surface of the chip, corresponding to each of the diaphragms.