JPH0293335A - Semiconductor type pressure sensor - Google Patents

Abstract

PURPOSE:To prevent the deterioration of characteristics by atmospheric moisture by hermetically confining the atmosphere on the circuit pattern forming side of a pressure-sensitive elements and providing a thermocouple in the formed hermetically closed chamber. CONSTITUTION:A cap 7 is fixed to the upper part of a stem 3 by an adhesive and the atmosphere is hermetically confined on the surface side of a pressure- sensitive element 1 to form a hermetically closed chamber 8 and the thermocouple 6 is mounted in said chamber 8 in order to measure the internal temp. thereof. The temp. of the chamber 8 is cleared by the thermocouple 6 and the effect thereof is removed by data processing and output caused only by pressure to be measured is obtained. Since the element 1 is hermetically closed on the surface side thereof, the element 1 receives no effect of the open air. By this method, the deterioration of characteristics due to the moisture contained in the atmosphere can be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a semiconductor pressure sensor.

In particular, the present invention relates to a semiconductor pressure sensor for measuring gauge pressure that can prevent characteristic deterioration due to moisture contained in the atmosphere.

[Conventional technology] Conventional semiconductor pressure sensors, in principle, suffer from corrosion of aluminum wiring and deterioration of pressure sensitivity characteristics due to the influence of moisture and corrosive substances introduced into the sensor chip surface by atmospheric air or other gases. It is known to occur easily.

Therefore, conventionally, in semiconductor pressure sensors for measuring gauge pressure, the circuit pattern-forming surface side of the pressure-sensitive element is covered with gel-like silicone and then exposed to the atmosphere. Further, the gas pressure to be measured is introduced from the back side of the pressure sensitive element through the pressure introduction port of the cage. In this way, by introducing the gas pressure to be measured from the back surface of the pressure sensitive element, the influence of moisture etc. does not reach the surface of the pressure sensitive element, which is the surface on which one circuit pattern is formed.

[Problems to be Solved] In the conventional semiconductor pressure sensor described above, the side exposed to the atmosphere is covered with gel silicone, but gel silicone has some moisture permeability, so
There is a problem in that the sensor chip surface is affected by moisture contained in the atmosphere, which tends to cause corrosion of the aluminum wiring and deterioration of pressure sensitivity characteristics.

The present invention has been made in view of the above-mentioned problems.
The object of the present invention is to provide a semiconductor pressure sensor for measuring gauge pressure that is free from characteristic deterioration due to moisture contained in the atmosphere.

[Means for Solving the Problems] In order to achieve the above object, the semiconductor pressure sensor of the present invention seals the circuit pattern forming surface side of a pressure sensitive element having a diaphragm to atmospheric pressure to form a sealed chamber, and also forms a sealed chamber. The structure is such that a thermoelectric body is provided inside the chamber.

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

First Embodiment> FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention, and FIG. 2 is a perspective sectional view of a pressure-sensitive element.

The features of this embodiment are that the structure seals the circuit pattern forming side of the pressure sensitive element having a diaphragm to seal gas pressure equal to atmospheric pressure, and that a thermocouple is installed inside the sealed chamber. It is in.

In FIG. 1, 1 is a pressure sensitive element, 2 is a pedestal, 3 is a stem, 4 is a pressure introduction port, 5 is a lead terminal, 6 is a thermocouple,
7 is a cap, and 8 is a sealed chamber.

The pressure sensitive element 1 is made of a silicon single crystal 10, and as shown in FIG. 2, a diaphragm 11 is formed from the back side by chemical etching or mechanical polishing, and a diffused resistor 12 and an aluminum wiring 13 are formed on the front side. is applied to form a bridge circuit.

The pedestal 2 is made of Pyrex glass, which has a coefficient of thermal expansion approximately equal to that of silicon, in order to reduce the influence of thermal distortion due to the difference in coefficient of thermal expansion between the stem 3 and the pressure-sensitive element 1. This pedestal 2 is bonded to the pressure sensitive element 1 by electrostatic welding, and is also fixed to the stem 3 with an adhesive.

The cap 7 is fixed to the upper part of the stem 3 with an adhesive to seal off the atmosphere on the surface side of the pressure sensitive element 1, thereby forming a sealed chamber 8.

A thermocouple 6 is installed to measure the internal temperature of this sealed chamber 8.

Next, the operation of such a semiconductor pressure sensor will be explained.

In this embodiment, the pressure in the sealed chamber 8 increases in proportion to the temperature as is clear from Boyle-Charles' law, but since the temperature inside the sealed chamber 8 can be determined by the thermocouple 6, the pressure in the sealed chamber 8 increases in proportion to the temperature. By processing the data using a computer or the like, this influence can be removed and the output caused only by the measured pressure can be known.

Since the surface side of the pressure-sensitive element 1 is sealed, if the air sealed in the sealed chamber 8 is kept dry, even if the external environment becomes a high-humidity atmosphere, the pressure-sensitive element 1 will not be affected by the air.

Second Embodiment FIG. 3 is a longitudinal sectional view of a second embodiment of the present invention, and FIG. 4 is a perspective sectional view of a pressure-sensitive element. In these figures, the same parts as in the first embodiment are designated by the same reference numerals, and the explanation thereof will be omitted.

The difference between this embodiment and the first embodiment is that, as clearly shown in FIG. The point is that the thin film thermocouple was formed.

In this embodiment, the thin film thermocouple 14 can directly measure the temperature of the surface of the silicon IO, so the advantage is that the temperature inside the sealed chamber 8 can be more accurately processed and corrected. There is.

Further, since the thermocouple 14 can be formed as an extension of the planar φ process used when forming the diffused resistor 12 and the aluminum wiring 13, there is an advantage that it is easier to manufacture.

[Effects of the Invention] As explained above, the present invention includes forming a sealed chamber by sealing the circuit pattern forming surface side of a voltage element having a diaphragm to atmospheric pressure, and providing a thermoelectric body inside this sealed chamber. This has the effect that it is possible to obtain a semiconductor pressure sensor for measuring gauge pressure that is free from characteristic deterioration due to moisture contained in the atmosphere.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the first embodiment of the present invention, FIG. 2 is a perspective cross-sectional view of the same pressure-sensitive element, FIG. 3 is a longitudinal cross-sectional view of the second embodiment of the present invention, and FIG. 4 is the same as the above. FIG. 2 is a perspective cross-sectional view of a pressure sensitive element. 1: Pressure sensitive element 2 2 Pedestal 3: Stem 4: Pressure introduction port 5: Lead terminal 6: Thermocouple 7: Cap 8: Sealed chamber 1O: Silicon

Claims (1)

[Claims] A semiconductor pressure sensor characterized in that a circuit pattern forming surface side of a pressure sensitive element having a diaphragm is sealed to atmospheric pressure to form a sealed chamber, and a thermoelectric body is provided inside the sealed chamber.