JPH1047911A - Strain sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor strain sensor which has a desired characteristics within a limited dimension. SOLUTION: An insulation film 3 is formed on the front surface side of a substrate 2, and a recessed/protruded part 5 is formed on the insulation film 3. On the recessed/protruded part 5, a gauge pattern 4 is formed. The gauge pattern 4 is formed in solid along the recessed/protruded part 5, so that a gauge length in 2-dimension term is shortened. Inversely, when the gauge pattern 4 is formed on the same plane, actual gauge length will be lengthened, for larger resistance value. With constant resistance value, a gauge length and gauge width in 2-dimension can be smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a strain sensor (or strain gauge) such as a semiconductor strain sensor using a semiconductor and a metal thin film type strain sensor using a metal thin film.

[0002]

2. Description of the Related Art Semiconductor strain sensors and metal thin film strain sensors are already known. For example, in a semiconductor strain sensor, when a stress is applied to a semiconductor according to the piezo effect, the resistance of the semiconductor deformed by the stress changes. When a current is passed through the semiconductor and the current flowing through the semiconductor is detected,
The applied stress can be detected. This is the principle of operation of the semiconductor strain sensor. Such a semiconductor strain sensor is used as a strain gauge to detect the strain itself,
It is applied to a pressure sensor for detecting pressure, an acceleration sensor for detecting impact during acceleration, and the like. See, for example, JP-A-2-62928.

A semiconductor in a semiconductor strain sensor must be formed with predetermined characteristics (parameters). However, when the semiconductor strain sensor is applied to a pressure sensor or the like, an excessive current may flow through the detection circuit of the pressure sensor due to the configuration of the system such as the pressure sensor. Therefore, when a semiconductor strain sensor is used as a pressure sensor or the like, it is necessary to set the semiconductor portion to a higher resistance value than when using a semiconductor strain sensor for strain measurement. However, if the size of the pressure sensor and the size of the semiconductor strain sensor are reduced due to the space and the like in which the pressure sensor and the like are arranged, there is an inconvenience that the resistance value becomes lower than a desired value.

Conventionally, in such a case, the thickness of the gauge pattern corresponding to the resistance wire of the semiconductor strain sensor is reduced, the width of the gauge pattern is reduced, and the gauge length of the gauge pattern is reduced in plan. By increasing the length, the resistance value of the gauge pattern is increased, and the above-mentioned demands and inconveniences have been addressed. 4 and 5 show an example of a conventional semiconductor strain sensor, in which an insulating film 22 is formed on a surface of a deformable substrate 21, and a gauge pattern 23 is formed on the insulating film 22. . Incidentally, Japanese Patent Application Laid-Open No. 2-62
Japanese Patent No. 928 discloses a technique for increasing the gauge length of a gauge pattern in a plane to increase the resistance value of the gauge pattern.

The semiconductor strain sensor has been described above.
The metal thin film strain sensor is in the same situation as the semiconductor strain sensor.

[0006]

However, in such a conventional method, when the thickness of the gauge pattern is reduced or the width of the gauge pattern is reduced, a processing system is further required. There is a problem that it is difficult to obtain desired gauge characteristics.

In addition, in the conventional countermeasures, when the gauge length is lengthened in a plane, there is an inconvenience that it is not possible to meet the demand for miniaturization of the semiconductor strain sensor and, consequently, miniaturization of the pressure sensor and the like. .

[0008] The above-mentioned problem in the semiconductor strain sensor is the same as that in the metal thin film strain sensor.

Accordingly, an object of the present invention is to provide a strain sensor such as a semiconductor strain sensor and a metal thin film strain sensor which can solve such problems of the conventional technology.

[0010]

A strain sensor according to the present invention is a strain sensor in which a semiconductor member or a metal member is formed in a predetermined pattern on an insulating film or an insulating portion provided on a substrate. Alternatively, the semiconductor device has a structure in which a pattern forming portion on which the metal member is formed is formed with unevenness, and the semiconductor member or the metal member is formed with unevenness along the pattern forming surface of the insulating film or the insulating portion.

By making the pattern forming portion uneven, the length of the semiconductor member or the metal member can be increased according to the step (length) of the uneven surface without increasing the plane dimension of the strain sensor. As a result, the electric resistance value of the semiconductor member or the metal member increases.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor strain sensor according to a first embodiment of the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 and 2 show a first embodiment of a semiconductor strain sensor as an example of a strain sensor according to the present invention. 1 is a plan view of a main part of the semiconductor strain sensor 1. FIG.
FIG. 2 is a sectional view taken along line A- of FIG. In these figures, the substrate 2 is formed in a thin plate shape from a metal that can be deformed by pressing. An insulating film 3 is formed on the substrate 2 by sputtering, vapor deposition, CVD, dipping, or the like. The insulating film 3 has an uneven portion 5 having a step at a portion (pattern forming portion) where at least a part of the gauge pattern 4 described later is formed in detail. The uneven portion 5 of the insulating film 3 is formed by forming a plurality of grooves 5a on the surface side (upper side in FIG. 2) of the insulating film 3 by photolithography using dry etching or the like. Then, the gauge pattern 4 is formed on the surface of the insulating film 3 on which the uneven portions 5 are formed as described above. After a material having a desired electric resistance value is formed on the insulating film 3 by sputtering, vapor deposition, CVD, or the like, the gauge pattern 4 is formed on the groove 5a of the insulating film 3 as shown in FIG. 4a are formed three-dimensionally along the surface of the uneven portion 5 of the insulating film 3. Note that a lead wire is connected to each end of the gauge pattern 4.

According to the present embodiment as described above, since the gauge pattern 4 is three-dimensionally formed on the insulating film 3 by the steps made of unevenness, even if the semiconductor strain sensors have the same plane size (gauge). Even if the length is the same), the step lengthens the substantial length of the gauge pattern 4 and increases the resistance value of the gauge pattern 4. Therefore, a large current can flow through the semiconductor strain sensor of the present invention.
Conversely, if the resistance value of the semiconductor strain sensor 1 according to the present embodiment is made equal to the resistance value of the conventional strain gauge, the gauge length and the gauge width can be reduced. As a result, miniaturization of the semiconductor strain sensor 1 and, consequently, the semiconductor strain sensor 1
It is possible to reduce the size of various sensors and devices provided with.

Second Embodiment FIG. 3 is a sectional view (a sectional view corresponding to the sectional view of FIG. 2) showing a second embodiment of the semiconductor strain sensor of the present invention.
In FIG. 3, the substrate 6 is formed in a thin film shape from a synthetic resin that can be deformed by pressing. In the semiconductor strain sensor 1 of the present embodiment, as shown in FIG. 3, an uneven portion 7 is formed in advance on the surface side (upper side in the figure) of the substrate 6.
A gauge pattern 9 is formed thereon with an insulating film 8 interposed therebetween. The insulating film 8 and the gauge pattern 9 are formed in the same manner as in the first embodiment. Also, a plurality of grooves 8a are formed in the insulating film 8, and a plurality of grooves 9a are also formed in the gauge pattern 9, so that the gauge pattern 9 is formed three-dimensionally as a whole. If an appropriate insulating base material is used for the synthetic resin forming the substrate 6, the substrate 6
The film itself becomes an insulating portion, and the insulating film 8 can be omitted.

As described above, since the gauge pattern 9 can be formed three-dimensionally also in the present embodiment, the same effect as in the first embodiment can be exerted. Further, the semiconductor strain sensor 1 according to the present embodiment has
Since the gauge pattern 4 is formed three-dimensionally and has a large resistance value, it is not necessary to reduce the thickness of the gauge pattern 9, to reduce the width of the gauge pattern 9, or to increase the planar gauge length. It is easy to manufacture and does not increase the defective rate.

In each of the above embodiments, the groove 4
Although the shapes of a, 5a, 8a, and 9a are formed in a rectangular shape, the shape is not limited to this, and the gauge patterns 4 and 9 may be three-dimensional, and may have a waveform or a triangular groove shape. or,
The number of the grooves 4a, 5a, 8a, 9a and the method of forming the insulating films 3, 8 and the gauge patterns 4, 9 are not limited to the above embodiments, but may be appropriately changed according to design conditions and the like. it can. Further, the grooves 4a, 5a, 8a, 9a
Need not necessarily be formed in the gauge pattern portion, but can be formed in the wiring portion or the correction resistor portion.

As described above, a semiconductor strain sensor has been described as an example of the strain sensor of the present invention. However, the present invention is not limited to a semiconductor strain sensor. Can be applied similarly to the semiconductor strain sensor.

[0019]

As is clear from the above description, in the strain sensor of the present invention, the unevenness is formed on the insulating film and at least a part of the gauge pattern is formed on the unevenness, or the unevenness is formed on the substrate. Since the gauge pattern is formed three-dimensionally by forming a portion and forming at least a part of the gauge pattern via the insulating film on the uneven portion, the conventional gauge length is reduced. However, the actual length of the gauge pattern can be made longer than that of the conventional example, and the electrical resistance value can be made larger than that of the conventional example even if the size is the same as that of the conventional example. Conversely, according to the present invention, when the resistance value is the same as that of the conventional example, the planar gauge length and gauge width of the gauge pattern can be reduced, and the size of the strain gauge can be easily reduced. .

Further, according to the present invention, as described above, the gauge pattern is formed three-dimensionally to reduce the size of the strain sensor. Therefore, the thickness of the gauge pattern can be reduced. It is not necessary to reduce the width, the gauge pattern can be easily formed, and there is no increase in the defective rate and the accompanying increase in the manufacturing cost.

Since the strain sensor of the present invention can be formed with arbitrary characteristics under a limited dimension, according to the present invention, a strain sensor applicable to various uses can be manufactured.

[Brief description of the drawings]

FIG. 1 is a plan view of a principal part showing a first embodiment of a semiconductor strain sensor as an example of a strain sensor of the present invention.

FIG. 2 is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a sectional view showing a second embodiment of a semiconductor strain sensor as an example of the strain sensor of the present invention.

FIG. 4 is a plan view of a main part of a conventional strain gauge.

FIG. 5 is a sectional view taken along the line BB of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2, 6 Insulating film 4, 9 Gauge pattern 5, 7 Uneven part

Claims (1)

[Claims] 1. A strain sensor in which a semiconductor member or a metal member is formed in a predetermined pattern on an insulating film or an insulating portion provided on a substrate, wherein a pattern forming portion on which the semiconductor member or the metal member is formed is formed. A strain sensor formed in irregularities, wherein a semiconductor member or a metal member is formed in irregularities along a pattern forming surface of the insulating film or the irregularities of the insulating portion.