JPS63195537A - Absolute pressure type semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To obtain a pressure sensor which consists of the small number of components and does not require high-level technique for machining, fixation, etc., by fixing a silicon pressure sensing chip which has a gauge resistance at a diaphragm part on a substrate made of AlN. CONSTITUTION:The pressure sensing chip is fixed on the AlN substrate whose heat expansion coefficient is approximately equal to that of silicon as the material of the pressure sensing chip, and the periphery of the substrate 6 is formed by resin molding and coupled airtightly with a lid body 7 where a pressure introducing pipe part 2 is united. Consequently, the pressure in the internal space 3 of a container is held equal to pressure to be measured which is applied from the part 2. The space 8 between the diaphragm part of the pressure sensing chip 1 and the substrate 6, on the other hand, becomes a reference pressure chamber, which is evacuated or charged with constant-pressure gas. A thick film wiring circuit 4 is formed of a printed thick film on the surface of the AlN substrate 6 to constitute an amplifying circuit, etc., which is connected to the terminal of the pressure sensing chip 1 by a thin wire 5. The thin film wiring circuit 4 is provided on the external surface of the substrate 6 as well. Consequently, the number of components is decreased and the sensor which does not require high-level technique for machining and fixation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an absolute pressure type semiconductor pressure sensor that applies a reference pressure to one side of a diaphragm portion on which a gauge resistor of a silicon plate is formed, and a measurement pressure to the other side.

[Conventional technology]

The general structure of a conventional absolute pressure type semiconductor pressure sensor is that
As shown in the figure, a silicon pressure-sensitive chip 1 having a diaphragm portion with a gauge resistance formed thereon is guided through a pressure impulse tube 2 through a pedestal 11 made of heat-resistant glass, silicon, or the like having a coefficient of thermal expansion similar to that of silicon. It is housed in a container that is fixed to a container and has a bottom portion 12 and a lid portion 13, through which a pressure guiding tube passes through in an airtight manner, and an internal space 3 serving as a pressure reference chamber. For example, when the temperature changes in the range of -40 to 120 degrees Celsius, stress due to the difference in thermal expansion coefficient between the pressure-sensitive chip and the support that supports it is applied to the diaphragm, deforming the diaphragm and making measurements as if it were This prevents the same result as when pressure is applied to deform the material. Furthermore, a ceramic substrate 14 such as 203 is housed in which a thick film wiring circuit 4 forming a control circuit such as an amplifier circuit is formed, and the thick film wiring circuit is used for connecting the terminals of the chip l, etc. They are connected by fine & j15 bonding.

[Problem that the invention seeks to solve]

However, in the above structure, the pedestal 11 is made of a special material and requires opening of pores, which is expensive, and also requires airtight adhesion between the pressure-sensitive chip 1 and the pedestal 11 and between the pedestal 11 and the impulse tube 2. This includes high cost factors such as the need for advanced technology.

An object of the present invention is to solve the above-mentioned problems and provide an absolute pressure type semiconductor pressure sensor that has a small number of parts and does not require advanced technology for processing, fixing, etc.

[Means for solving problems]

In order to achieve the above object, the present invention provides a silicon pressure-sensitive chip having a gauge resistor in a diaphragm portion formed by forming a recess in the center of one side on a substrate made of aluminum nitride. The substrate is hermetically connected to a lid having a pressure-sensitive port, and a thick film wiring circuit is formed on the surface of the substrate.

(Function) With the above structure, the space between the diaphragm part of the pressure-sensitive chip and the MN board becomes a reference pressure chamber, and the space between the board and the lid body is connected to the pressure-conducting port of the lid body. By introducing the measurement pressure, the diaphragm part deforms and the pressure can be detected.

Since AZN has a coefficient of thermal expansion similar to that of silicon, no stress is applied to the pressure-sensitive chip even when the temperature changes.

〔Example〕

FIG. 1 shows an embodiment of the present invention, and parts common to those in FIG. 2 are given the same reference numerals. In this case, a silicon pressure-sensitive chip 1 is fixed on an AZN substrate 6. A
ZN has a coefficient of thermal expansion of 4.5 x 10-”/Vz
Q, 7. Less than OX 10-'/K, 3.5
The coefficient of thermal expansion of St is approximately x10-''/.

The periphery of the substrate 6 is made by resin molding, and the impulse tube part 2
is airtightly connected to the lid body 7, which is integrated with the lid body 7.

As a result, the pressure in the internal space 3 of the container was maintained at the measured pressure introduced from the impulse pipe section 2. It will be done. On the other hand, the space 8 between the diaphragm portion of the pressure-sensitive chip 1 and the substrate 6 serves as a pressure reference chamber, and is evacuated or filled with gas at a constant pressure. A thick film wiring circuit 4 is formed by a printed thick film on the surface of the A7N substrate 6, and constitutes an amplifier circuit, etc., and is connected to the terminals of the pressure sensitive chip 1 by thin wires 5. The thick film wiring circuit 4 is also provided on the outer surface of the substrate 6 as shown. For example, it is effective to provide a resistor, etc., which is adjusted after connecting the chip 1 and the control circuit, on this outer surface, and after adjustment, the resistor is covered with a resin layer 9 for surface protection.

〔Effect of the invention〕

According to the present invention, a pressure-sensitive chip is mainly fixed to an A7N substrate having a coefficient of thermal expansion approximately equal to that of silicon, which is a pressure-sensitive chip material, and this substrate is also used as a part of a container and a substrate for a thick-film wiring circuit. By doing so, the pedestal and separate circuit board are omitted, reducing the number of parts. Furthermore, by forming a pressure guide port in a part of the container and using the internal space of the container as a measurement pressure chamber, and the space between the diaphragm part of the pressure-sensitive chip and the substrate as a pressure reference chamber, the structure is simple and the manufacturing process is simple. A compact, high-precision absolute pressure type semiconductor pressure sensor with high reliability can be obtained at low manufacturing cost without requiring any special technology.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is a sectional view of a conventional example. 1: Pressure sensitive chip, 2: Impulse tube section, 4: Thick film wiring circuit, 6
: A7N board, 7: Lid body.

Claims (1)

[Claims] 1) A silicon pressure-sensitive chip with a gauge resistor in a diaphragm portion formed with a recess formed in the center of one side is fixed onto a substrate made of aluminum nitride with the recess facing the substrate,
An absolute pressure type semiconductor pressure sensor, wherein the substrate is airtightly coupled to a lid having a pressure-conducting port, and a thick film wiring circuit is formed on the surface of the substrate.