JPH02296116A - Vibration detecting device - Google Patents

Abstract

PURPOSE:To improve accuracy and to decrease a cost by fixing two vibrating plates to the side surfaces of thick parts, and forming a strain detecting part. CONSTITUTION:In a strain detecting part 11, vibrating plates 12a and 12b are fixed to the side surfaces of thick parts 8a and 8b with a bonding agent 16 and fixed to a fixing stage 13. When vibration is applied to such a vibration detecting apparatus, the strain detecting part 11 acts as a mass. Force F1 acts, and two vibrating plates 12a and 12b are vibrated. Then, the resistance value of a piezoelectric resistor 2 is changed. The change in resistance value is taken out with a Wheatstone bridge circuit as an electric signal. Thus a highly accurate vibration detecting device can be manufactured at a low cost.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an imaging detection device widely used in general industry, and in particular, to a mechanical imaging and detection device that utilizes the piezoresistance effect in which the resistance value of a semiconductor changes with stress. The present invention relates to a vibration detection device that converts vibrations into electrical signals.

[Conventional technology]

An example of a conventional vibration detection device is shown in Fig. 7, another example is shown in Fig. 8, and further examples are shown in Figs. 9 and 10. In the detector, a spring 32 is attached to a U-shaped fixed base 31, and a mass part 30 and a vibration transmission rod 33 are attached to the center of the spring 32. The fixed base 31 is set with one point in the middle of the vibration transmission rod 33 as the fulcrum 34.
A recording pen 35 is attached to the tip of the vibration transmitting rod 33, and the recording pen 35 is recorded on a recording paper attached to the fixed base 31. In FIG. When applied, the force F2 acts on the mass part 30, and the spring 3
2 vibrates. Due to this vibration, the recording pen 35 attached to the tip of the vibration transmission rod 33 vibrates as shown at 82, and the recording is recorded on the recording paper 36. In addition to the above-mentioned method of using a vibration transmitting rod, the vibration detection device that uses the vibration of a spring has a method in which, for example, a magnet attached to the spring is vibrated by the vibration of the spring, and the surrounding area of the magnet is A method is known in which vibration is detected by generating an induced voltage in a fixed coil.

Next, the example shown in FIG. 8 is a vibration detection device that uses a strain gauge to detect strain caused by vibration of a diaphragm, and includes a fixed part 41, a diaphragm 42 attached perpendicularly to the fixed part 41, and an itt attached to the tip of the diaphragm 42.
Strain gauges 43a and 43b are attached to opposite surfaces of the diaphragm 42. 8th
In the figure, when vibration A is applied to the fixed base 41, a force F3 acts on the mass portion 44, causing the diaphragm 42 to vibrate. This vibration causes the strain gauges 43a and 4 attached to the diaphragm 42 to
3b, B3-P and B3-N distortions occur, respectively.
converted into an electrical signal.

Finally, in the examples shown in FIGS. 9 and 10, the principle is the same as that of the device shown in FIG. In mass part,
A piezoresistor 52 for detecting strain is built into the base of the surface of the diaphragm 57. This manufacturing method will be explained below.0 For example, a p-type piezoresistor 52 is formed on the surface of the root portion of a diaphragm 57 on an n-type silicon substrate 51 using an impurity diffusion formation technique, and an oxide film 53 is formed thereon using a thermal oxidation formation technique. , and a nitride film 55 for 0th order surface protection for wiring is formed using an aluminum vapor deposited film 54. For wiring with the outside, a part of the nitride film 55 is removed by etching, and a cavity 60 is formed by a zero-order chemical etching technique to form a pad 56, and a diaphragm 57 and a mass part 58 are formed.
complete. In FIG. 1O, when vibration A is applied to the fixed base 59, a force F4 acts on the mass part 5, causing the diaphragm 57 to vibrate. This vibration causes a strain B4 in the p-type piezoresistor 52 built into the surface of the root portion of the diaphragm 57, which is converted into an electrical signal.

[Problem to be solved by the invention]

However, in each of the vibration detection devices shown in FIGS. 7 and 8 described above, after detecting a vibration signal, peripheral circuits for processing the signal, such as a signal characteristic correction circuit, a signal amplification circuit, a temperature compensation circuit, etc. It is necessary to install them as separate elements, which increases the cost. Also, Figures 9 and 10
In the vibration detection device shown in the figure, a semiconductor substrate includes a fixed base and a diaphragm.

The mass part and the piezoresistor have a -° body configuration, and it is easy to build the above-mentioned peripheral circuit into a part of the fixed base made of this semiconductor substrate using RC technology. However, in this vibration detection device, the diaphragm and the mass part are manufactured as an integral structure using chemical etching technology, and it is difficult to manufacture the thickness and width of the diaphragm and the dimensions of the mass part with high precision using chemical etching technology. However, as a vibration detection device, there is a problem of low accuracy.

The invention! ! ! ! The object of the present invention is to solve the above-mentioned problems and provide a vibration detection device in which the piezoresistor of the vibration detection device and its peripheral circuit are integrated on a semiconductor substrate, and the dimensions of the diaphragm and the 'it part can be manufactured with high precision. It's about doing.

[Means to solve the problem]

In order to solve the above-mentioned problem, in the vibration detection device of the present invention, a groove is dug in the center of one surface of the semiconductor substrate, reaching from one end to the other end. A strain detecting section including a thin section and a thick section on both sides of the thin section, and a piezoresistor formed at the boundary between the thin section and the thick section on the other surface of the semiconductor substrate; It consists of two diaphragms installed perpendicularly and in parallel on a fixed base, and the strain detection section fixes the thick parts on both sides between the two diaphragms to each of the diaphragms. do it like this.

[Effect]

In the vibration detection device of the present invention, the strain detection section is formed by etching a groove in the center of the semiconductor substrate, forming a thin section and thick sections on both sides, and detecting strain at the boundary between the thin section and the thick section. It is designed to incorporate a piezoresistor for detection,
The technology of forming thin-walled parts by digging grooves by etching has been established as a technology for mass-producing silicon pressure-sensitive diaphragms for pressure sensors used in a wide range of industrial fields, including automobiles, and the dimensions of the thin-walled parts are high. It can be manufactured with high precision, and as a result, strain detectors with small variations in sensitivity and high accuracy can be manufactured.

In addition, since the diaphragm is a separate component from the strain detector made of a semiconductor substrate, it is easy to select and adjust its material and shape, and the variation in sensitivity of the vibration detection device is small (
It is possible to manufacture products with high precision. Furthermore, peripheral circuits for signal processing and the like can be built into the thick portion of the semiconductor substrate constituting the strain detector using IC technology, and an integrated circuit configuration can be achieved without requiring separate circuit elements.

〔Example〕

An embodiment of the vibration detection device of the present invention will be described with reference to FIGS. 1 to 6. FIG. 5 is a plan view of a strain detection section used for vibration detection in the vibration detection device of the present invention, and FIG. 6 is a sectional view taken along the line cc' in FIG. The manufacturing process will be explained below in order. On the surface of the n-type silicon substrate 1, two p-type piezoresistors 2 are installed on the left and right sides using impurity diffusion technology at the boundaries between the thin-walled portion 7 and thick-walled portions 8a and 8b, which will be manufactured later.
Form one by one. An oxide film 3 is formed on this, and this surface is protected by a zero-order silicon nitride film 5 which connects these piezoresistors 2 with an aluminum wiring &I film 4. After that, a part of the silicon nitride film 5 is removed to form a band portion 6.
expose. Finally, a hole 1l19 is etched on the back surface of the n-type silicon substrate 1, and thick inner parts 8a and 8b are formed at the same time as the thin part 7, thereby completing the strain detection part 11.

In addition, if necessary, peripheral circuits for signal processing, etc. are built into the surface of the thick portion using IC technology.

As shown in FIG. 1, this strain detecting section 11 is fixed to the side surfaces of the thick portion with diaphragms 12a and 12b, respectively, using an adhesive 16 or the like, and then fixed to a fixing base 13. As shown in FIG. 2, the diaphragm 12a or 12b can also be used as a printed circuit board, and the figure shows that the pad portion 6 of the distortion wheel output portion 11 and the external wiring 14 of the printed circuit board 12a are connected by an aluminum wire 15. Indicates a connected state. Although not shown, it is also possible to mount peripheral circuits on the fixed base 13 that could not be incorporated into the strain detection section.

When the vibration indicated by A in FIG. 1 is applied to the vibration detection device thus completed, the strain detection section 11 acts as a mass, and the force Pl acts to cause the two diaphragms 12a and 12b to vibrate. Figure 3 shows the state of the strain detection section at that time, and p
A strain of 81-P is generated in one 28 of the shaped piezoresistors 2, and a strain of 81-N is generated in the other 2b, and the resistance value thereof changes. This change in resistance value is extracted as an electrical signal by the Wheatstone bridge circuit shown in FIG.

[Effects of the Invention] According to the present invention, the distortion of the main part of this vibration detection device can be reduced by utilizing the technology for mass production of silicon pressure-sensitive diaphragms of pressure sensors already used in a wide range of industrial fields including automobiles. The detection section can be manufactured with high precision, the peripheral circuitry for signal processing etc. can be built into the thick part of the strain detection section made of a semiconductor substrate using IC technology, and the strain detection section made of a diaphragm and a semiconductor substrate. Since the diaphragm is made into a separate component, the selection and adjustment of the material and shape of the diaphragm are facilitated, and a highly accurate vibration detection device with small variations in sensitivity can be obtained at low cost.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of the vibration detection device of the present invention, FIG.
4 is a signal detection circuit diagram of the strain detection section, FIG. 5 is a plan view of the strain detection section, and FIG. 6 is a sectional view taken along the line c-c' in FIG. 5. , FIG. S is a sectional view of an example of a conventional vibration detection device, FIG. 8 is a sectional view of another example of a conventional vibration detection device, and FIG. 9 is a sectional view of yet another example of a conventional vibration detection device. , FIG. 10 is a sectional view taken along the line DD' in FIG. 9. 1: Semiconductor substrate 2: Piezoresistor 7 Two thin parts 8a 8b: Thick part 9: Groove 11: Strain detection parts 12a, 12b: Vibration plate 13: Fixed base Fig. 1 Fig. 5 Fig. 6 Fig. 3 Fig. 7 Figure 8

Claims (1)

[Claims] 1) A groove reaching from one end to the other end is dug in the center of one surface of the semiconductor substrate, thereby forming a thin part in the center of the semiconductor substrate and thick parts on both sides thereof. formed, and
a strain detection section in which a piezoresistance is formed at the boundary between a thin wall portion and a thick wall portion on the other surface of the semiconductor substrate; a fixing base; and two parts mounted perpendicularly and parallel to the fixing base. 2. A vibration detection device comprising: a diaphragm, wherein the strain detection section is formed between the two diaphragms by fixing thick portions on both sides of the diaphragm to the diaphragm.