JPS61132832A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To absorb and soften a distortion caused by a temperature variation, to deteriorate no output characteristic of a sensor, and also to reduce the cost of manufacture and parts by providing a cylindrical supporting base and an annular pedestal on a base, and suspending and fixing a sensor body to this pedestal. CONSTITUTION:A cylindrical supporting base 3 consisting of stainless steel is fixed by using an adhesive agent onto a base 11 of a case 1 of a semiconductor pressure sensor, and thereafter, an annular pedestal 4 consisting of silicon is fixed to the upper end face of the supporting base 3. Subsequently, a sensor body 2 which has formed a piezo-resistance element 2c consisting of P type silicon is fixed in a suspending state by sticking the upper face of a base part 2b to the pedestal 4. In this way, even if a fluid to be measured or an ambient temperature is varied and the base 11 is brought to thermal expansion, a distortion transmitted to the sensor body 2 through the pedestal 4 is absorbed and softened remarkably, and also it is not required to provide a compensating resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor pressure sensor that mainly detects the pressure of fluid such as gas or liquid using a pressure sensitive element such as a piezoresistive element.

[Prior art]

Generally, this type of semiconductor pressure sensor has a piezoresistive element installed in a silicon diaphragm, and the resistance value of the piezoresistive element changes in response to deformation of the diaphragm due to a pressure difference between the two sides of the diaphragm. It is configured to be used.

FIG. 2 is a cross-sectional structural diagram showing a conventional semiconductor pressure sensor. An installation base 9 is fixed on a base 11 constituting a case 1 using an adhesive 8, and a sensor main body 2 is mounted on this installation base 9. The sensor main body 2 is connected to the lead pins 5a, 5b via the lead wires 4a, 4b, and the cap 12 is fitted and fixed to the base 11 so as to cover these.

A pressure introduction port 11a is connected to the base 11 at a portion facing region A on one side of the diaphragm portion 2a, and a pressure introduction pipe 12a is connected to the top of the cap 12 facing region B on the other side of the diaphragm portion 2a. I'm being forced to do it.

- In an n-type silicon semiconductor substrate, the main body 2 has a diaphragm part 2a with a thinner center part and an annular base part 2b with a thicker peripheral part, and impurities are diffused into multiple locations on the surface of the diaphragm part 2a. The lower surface of the annular base 2b is fixed on a mounting base 9, and together with the mounting base 9, it is fixed on a base 11. The installation stand 9 is made of silicon and has an annular shape, and is provided to absorb and alleviate strain caused by the difference in thermal expansion coefficient between the base 11 and the sensor body 2 due to temperature changes together with the adhesive 8.
JP-A-59-102131, JP-A-55-1714).

[Problem that the invention seeks to solve]

However, in the conventional semiconductor pressure sensor as described above, the function of absorbing and alleviating thermal strain between the base 11 and the sensor body 2 is insufficient (the output characteristics of the sensor body 2 change, resulting in a significant drop in detection accuracy). There were some inconveniences that affected me.

For this reason, a conventional method has been adopted in which a compensating resistor exhibiting pressure characteristics similar to those of the piezoresistive element is disposed outside the case 1 to eliminate output fluctuations due to distortion due to temperature changes.

However, when such a method is adopted, there are problems in that the cost of parts increases, the number of manufacturing steps increases, and the cost of the product inevitably increases.

[Means for solving problems]

The present invention has been made in view of the above circumstances, and its purpose is to support the sensor body by interposing a cylindrical support stand or an annular support stand on the base, thereby reducing thermal strain. An object of the present invention is to provide a semiconductor pressure sensor that has an increased absorption and relaxation function and can significantly reduce the influence of thermal strain on output characteristics.

The semiconductor pressure sensor according to the present invention is characterized in that the semiconductor pressure sensor has a sensor main body having a diaphragm portion formed with a pressure-sensitive element having a piezoresistance effect fixed in a case, and one end portion is fixed on the base of the case. The sensor comprises a cylindrical support stand standing upright, and an annular pedestal concentrically fixed to the other end of the support stand, and the sensor body is suspended and fixed to the lower surface of the pedestal. shall be.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a cross-sectional structural diagram of a semiconductor pressure sensor according to the present invention (hereinafter referred to as a product of the present invention), in which 1 indicates a case and 2 indicates a sensor body. Case 1 is a base 11. The sensor main body 2 is disposed on a base il consisting of a cap 12 with a support stand Wi4 interposed therebetween, and the sensor main body 2 is connected to a lead wire 5a.

5b to lead pins 6a and 5b, and in this state, cap 12 is placed to cover sensor body 2, and the lower end periphery of camp 12 is externally fitted and fixed to base 11, so that they are integrally connected to each other. ing.

The diaphragm part 2 of the sensor body 2 is located in the center of the base 11.
A pressure introduction hole 11a is opened facing one side area A separated by a, and a plurality of lead pins 6a and 6b are erected through the peripheral edge in an airtight manner.

On the other hand, in the center of the top of the camp 12, there is a pressure introduction port 12a facing the area B on the other side separated by the diaphragm part 2a.
It is forced to open.

The support stand 3 is made of stainless steel and has a cylindrical shape, and its lower end is fixed to the center of the upper surface of the base stand 11 using an adhesive. The pedestal 4 is made of silicon and is formed into an annular shape, and has an outer diameter that is approximately equal to the outer diameter of the support 3 and an inner diameter that is smaller than that of the support 3. The diameter of the support base 3 increases as the diameter increases towards the end, and the lower end surface is fixed to the upper end surface of the support base 3 using an adhesive.

The sensor main body 2 is made of n-type silicon and has a thin center part to form a diaphragm part 2a, and a thick peripheral part to form a circular base part 2b. A piezoresistance element 2C made of p-type silicon is formed by diffusing impurities into locations, and the upper peripheral edge of the annular base 2b is connected to the pedestal 4.
It is glued to the pedestal 3 and fixed in a hanging state below the pedestal 3.

Therefore, in the product of the present invention as described above, the sensor body 2
Both side areas A of the diaphragm part 2a in .

When a difference occurs in the pressure at 8, the diaphragm portion 2a deforms accordingly, and the resistance value of the piezoresistive element 2c changes in accordance with this deformation, and this change causes the lead wires 5a, 5b to change.
It is detected as a pressure difference through the + lead pins 6a and 6b.

In such a product of the present invention, when the temperature of the fluid to be measured, such as gas or liquid, or the surrounding atmosphere changes, the base 11 thermally expands, but the change in the thickness direction is not detected by the sensor. On top of main body 2.

Changing only the downward position does not affect the output characteristics in any way, and changing the base 11 in the diametrical direction
A force to expand or contract the diameter is exerted on the lower end of the support base 3, but since the support base 3 has a circular shape, the deformation resistance against such an external force in the direction of expanding or contracting the diameter at one end is Moreover, even if deformation occurs, the deformation is significantly reduced on the other end side, and as a result, the strain transmitted to the sensor body 2 through the pedestal 4 is largely absorbed and alleviated, and its influence on the output characteristics of the sensor body 2 is reduced. This can be significantly reduced,
No compensation resistor is required as in the prior art.

〔effect〕

As described above, the product of the present invention has a structure in which a cylindrical support is erected on the base, an annular pedestal is fixed on the support, and the sensor body is fixed in a suspended manner at the bottom of the pedestal. Therefore, there is a difference in the coefficient of thermal expansion between the base and the sensor body, and even if the base deforms due to temperature changes, the strain transmitted to the sensor body through the support base is significantly absorbed and alleviated. The present invention has excellent effects such as not deteriorating the output characteristics of the sensor body, eliminating the need for a compensation resistor, reducing manufacturing costs and component costs, and having no effect on measurement accuracy.

4, [ii! Brief Explanation of Part 1 FIG. 1 is a cross-sectional structural diagram of the product of the present invention, and FIG. 2 is a cross-sectional structural diagram of a conventional product.

■...Case 2...Senna main body 2a...Diaphragm portion 2b...Annular base 2c...Piezo resistance element 3...Support stand 4...Pedestal 5a, 5b.
...Lead wires 6a, 6b...Lead pin 11...
Base 11a...Pressure inlet 12...Cap
12a...Pressure introduction patent Applicant: Sanyo Electric Co., Ltd. Agent Patent attorney: Noboru Kono Figure 2

Claims (1)

[Claims] 1. In a semiconductor pressure sensor in which a sensor body having a diaphragm portion formed with a pressure-sensitive element having a piezoresistance effect is fixed in a case, a cylindrical pressure sensor with one end fixed to the base of the case is provided. 1. A semiconductor pressure sensor comprising a support stand and an annular pedestal concentrically fixed to the other end of the support stand, wherein the sensor main body is suspended and fixed to the lower surface of the pedestal.