JPH05133827A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To obtain a semiconductor pressure sensor with a high reliability by using for pressure measurement when a pressure is given from a rear surface of a pressure-sensing chip through a pressure medium which consists of a gelshaped substance. CONSTITUTION:A pressure-sensing chip 3 is provided on a base 1 through a pedestal 2, and an external connection terminal 5 is connected to the pressure- sensing chip 3 through a lead wire 4. A pressure-introducing hole which is connected to a pressure-guiding pipe 6 is formed at the base 1 and the pedestal 2 and an introduction path for guiding a measurement medium is formed. A diaphragm part which is deformed according to a pressure is formed at the pressure-sensing chip 3 and a piezo resistance gauge is formed on the surface. A gel-shaped fluorosilicone, namely a fluoro silicone gel 8 is provided at a penetration hole part which forms the introduction path of the measurement medium which is provided mainly at the base 1 and the pedestal 2. A dimension of a pressure introduction hole which is provided at the base 1 and the pedestal 2 is formed to be equal to or larger than that of a recessed part of a rear surface of the pressure-sensing chip 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor pressure sensor used for measuring a gasoline vapor pressure in a gasoline tank of an automobile, an oil pressure of a hydraulic machine, various water pressures and the like.

[0002]

2. Description of the Related Art Generally, a semiconductor pressure sensor has an IC on the front surface of a pressure-sensitive chip having a diaphragm portion which is thinned by forming a recess on the back surface and is deformed in response to pressure.
Using a piezoresistive gauge formed by the same method as in the manufacturing of (integrated circuit), pressure is measured by applying a pressure from a measuring medium to the pressure sensitive chip.

The piezoresistive gauge portion of the pressure-sensitive chip of this semiconductor pressure sensor is vulnerable to contamination, and its performance may be deteriorated due to contamination. For this reason, contaminated liquids,
As a semiconductor pressure sensor for measuring the pressure of a medium which easily contaminates the piezoresistive gauge of the pressure-sensitive chip, such as a liquid which itself may contaminate the piezoresistive gauge, it is conventionally shown in FIG. Those having such a configuration have been used.

The semiconductor pressure sensor shown in FIG. 2 is a semiconductor pressure sensor of a type called a gauge pressure type reverse pressure type, and a pressure sensitive chip 23 is provided on a base 21 via a pedestal 22, and this pressure sensitive chip is provided. An external connection terminal 25 is connected to 23 via a lead wire 24. The pedestal 22 is
It is formed using silicon, glass, or the like as a material. Base 2
1 and the pedestal 22 are formed with a through hole communicating with a pressure guiding pipe 26 provided in the lower portion of the base 21 and forming an introduction path for introducing the measurement medium. The upper surface of the base 21, the pedestal 22, the pressure-sensitive chip 23, and the lead wire 24 are covered with a can 27, and the external connection terminal 25 penetrates the base 21 and is led to the outside.
An air release hole is formed in the center of the upper portion of the can 27. As described above, the pressure-sensitive chip 23 is provided with the concave portion on the back surface side to form the diaphragm portion which is deformed according to the pressure, and the surface thereof is provided with the piezo resistance gauge (not shown). There is. When the gauge pressure type is not used, that is, when the absolute pressure type is used, the inside of the can 27 is evacuated without providing the atmosphere opening hole in the can 27.

In this type of semiconductor pressure sensor, the measurement medium is introduced into the rear surface side of the diaphragm portion of the pressure-sensitive chip 23 (the side where the concave portion is formed, not the side where the piezoresistive gauge is provided), and this portion is introduced into this portion. To receive the measured pressure.
Therefore, the through holes provided in the base 21 and the pedestal 22, and the pressure guiding pipe 2 provided in the lower portion of the base 21.
6, a gel-like protective material layer, for example, a gel-like fluorosilicone, is provided mainly in the through-hole portion provided in the base 21 and the pedestal 22 in the introduction path of the measurement medium formed in communication with the back surface of the pressure-sensitive chip 23. That is, the fluorosilicone gel 28 is provided. That is, the concave side, which is the back surface of the pressure-sensitive chip 23, is covered with the fluorosilicone gel 28, and the pressure of the measurement medium is transmitted to the pressure-sensitive chip 23 via the fluorosilicone gel 28.

Fluorosilicone has good solvent resistance and water resistance, and gelled fluorosilicone does not affect the pressure-sensitive characteristics of pressure-sensitive chip 23.
Therefore, the semiconductor pressure sensor of FIG.
Using the basic structure to apply pressure directly from the back side of 3,
Moreover, a fluorosilicone gel 28 is provided so as not to directly contact the pressure-sensitive chip 23 with the measuring medium.
In the semiconductor pressure sensor shown in FIG. 2, since contaminants and the like do not directly adhere to the pressure-sensitive diaphragm, the characteristics will not change due to contamination. In addition, the characteristics are not changed due to the adhesion of the adhesive component to the pressure-sensitive diaphragm, and the reliability is high.

[0007]

However, the structure shown in FIG. 2 has the following problems. In the structure of FIG. 2, the fluorosilicone gel 28 forming the protective material layer is provided between the pedestal 22 portion for supporting the pressure-sensitive chip 23 provided below the pressure-sensitive chip 23 and the pressure-sensitive diaphragm portion. Narrow portion (this portion is formed due to the dimensional relationship between the concave portion provided for forming the diaphragm portion in the pressure-sensitive chip 23 and the pressure introduction path for introducing pressure through the fluorosilicone gel 28). Is usually
It has a thickness of about 0.2 to 0.3 mm) and is partially confined. This narrow portion causes a problem in the filling property in the step of injecting the fluorosilicone gel 28, and the coefficient of thermal expansion of the fluorosilicone gel 28 is about 10 as compared with the pedestal 22, the pressure-sensitive diaphragm, and the like.
Since it is about 0 times as large, it affects the temperature characteristics of the pressure sensor after completion. The filling properties of these fluorosilicone gels 28 and the temperature characteristics of the sensor affect the basic performance of the pressure sensor, which causes the reliability to be impaired.

The present invention has been made in view of the above circumstances, and is used for pressure measurement when pressure is applied from the back surface of a pressure-sensitive chip through a pressure medium made of a gel-like substance, and is highly reliable. It is an object of the present invention to provide a semiconductor pressure sensor capable of achieving high performance.

[0009]

A semiconductor pressure sensor according to the present invention has a diaphragm portion which can be deformed in response to pressure by forming a recess on one surface of a semiconductor chip to reduce the thickness of a predetermined portion. A semiconductor pressure sensor having a structure in which a pressure of a measuring medium is applied to the one surface of the diaphragm portion of the pressure sensitive chip formed on the other surface of the diaphragm portion and a strain gauge is formed on the other surface of the diaphragm portion. It is characterized in that the hole size of the pressure introducing hole of the portion supporting the is formed to be equal to or larger than the size of the concave portion forming the diaphragm part.

[0010]

In the semiconductor pressure sensor of the present invention, the diaphragm portion is formed on one surface of the semiconductor chip to reduce the thickness of the predetermined portion, thereby forming the diaphragm portion which can be deformed in response to the pressure. In the semiconductor pressure sensor having a structure in which the pressure of the measurement medium is applied to the one surface of the diaphragm portion of the pressure-sensitive chip in which the strain gauge is formed on the other surface, the pressure of the portion supporting the pressure-sensitive chip Since the hole size of the introduction hole is formed to be equal to or larger than the size of the recess forming the diaphragm part, the above-mentioned narrow part is not formed, and high reliability is obtained when a gel-like substance is used as the pressure medium. It becomes possible to obtain.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of a semiconductor pressure sensor according to an embodiment of the present invention. The semiconductor pressure sensor shown in FIG. 1 has a base 1, a pedestal 2, a pressure sensitive chip 3, a lead wire 4, an external connection terminal 5, a pressure guiding pipe 6, a can 7 and a fluorine as a protective material. It is basically the same as the base 21, the pedestal 22, the pressure-sensitive chip 23, the lead wire 24, the external connection terminal 25, the pressure guiding pipe 26, the can 27, and the fluorosilicone gel 28 shown in FIG.

That is, the pressure sensitive chip 3 is provided on the base 1 via the pedestal 2, and the external connection terminal 5 is connected to the pressure sensitive chip 3 via the lead wire 4. Through holes are formed in the base 1 and the pedestal 2 so as to communicate with the pressure guiding pipe 6 provided in the lower portion of the base 1 in the drawing, and form an introduction path for introducing the measurement medium. Upper surface of base 1 shown in the figure, pedestal 2, pressure-sensitive chip 3, and lead wire
Is covered with a can 7, and the external connection terminal 5 extends through the base 1 to the outside. An atmosphere opening hole is formed in the center of the upper portion of the can 7. The pressure-sensitive chip 3 forms a diaphragm portion that deforms in response to pressure, and a piezoresistive gauge is formed on the surface thereof.
When the gauge pressure type is not used, that is, when the absolute pressure type is used, the inside of the can 7 is evacuated without providing the atmosphere opening hole in the can 7.

A through hole provided in the base 1 and the pedestal 2 and a pressure guiding pipe 6 provided in the lower portion of the base 1 are connected to the back surface of the pressure-sensitive chip 23 to form an introduction path for the measurement medium. A gel-like fluorosilicone, that is, a fluorosilicone gel 8 as a protective material layer is provided mainly in the through-hole portions provided in the base 1 and the pedestal 2. That is, the back surface of the pressure sensitive chip 3 is covered with the fluorosilicone gel 8, and the pressure of the measurement medium is transmitted to the pressure sensitive chip 3 via the fluorosilicone gel 8. The fluorosilicone has good solvent resistance and water resistance, and the gelled fluorosilicone does not affect the pressure-sensitive characteristics of the pressure-sensitive chip 3.

The structure shown in FIG. 1 differs greatly from the structure shown in FIG. 2 in that it forms an introduction path for the measurement medium provided in the base 1 and the pedestal 2 as shown in FIG. The size of the through hole (portion mainly filled with the fluorosilicone gel 8), that is, the pressure introducing hole is equal to or larger than the size of the recess (for forming the diaphragm part) on the back surface of the pressure sensitive chip 3. That is.
For example, if the cross-sectional shape of the through hole and the opening shape of the recess are both circular, the cross-section of the through hole has a larger diameter than the opening of the recess. Of course, the dimensional relationship may be such that the opening shape of the concave portion matches or fits within the cross-sectional shape of the through hole regardless of the shapes of both.

By doing so, a narrow portion is not formed between the pedestal 2 and the pressure-sensitive diaphragm, so that the fluorosilicone gel 8 is not confined. Therefore, fluorosilicone gel 8
The filling property in the injection step is improved, and the thermal characteristics of the fluorosilicone gel 8 are not affected by the temperature characteristics after the pressure sensor is completed.

As the protective material layer, another silicone-based gel-like substance may be used instead of the fluorosilicone gel, or another gel-like substance may be used, and the back side of the diaphragm portion of the pressure-sensitive chip may be covered. Any material may be used as long as it protects from the measurement medium and does not hinder the operation of the diaphragm portion. Further, in the above description, the case where the pressure introduction path is filled with the fluorosilicone gel 8 as the protective material layer has been described, but in any case, if the pressure is received via the gel medium as the pressure medium, the above description is applied. The composition of is effective. Further, the through holes for introducing the measurement medium, which are usually provided in the base 1 and the pedestal 2, are formed to have the same shape and size, but if at least the through holes of the pedestal 2 are set to the above-mentioned size, it is extremely difficult. Since the narrow portion is not formed, the effect of the present invention can be obtained.

[0017]

As described above, according to the present invention, a diaphragm portion which can be deformed in response to pressure is formed by forming a recess on one surface of a semiconductor chip to reduce the thickness of a predetermined portion. In the semiconductor pressure sensor having a structure in which the pressure of the measurement medium is applied to the one surface of the diaphragm portion of the pressure sensitive chip in which the strain gauge is formed on the other surface of the diaphragm portion, the pressure sensitive chip is The hole size of the pressure introducing hole of the supporting portion is formed to be equal to or larger than the size of the recess forming the diaphragm portion, and is used for pressure measurement in which pressure is applied through a pressure medium made of a gel-like substance, A semiconductor pressure sensor that can obtain high reliability can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a semiconductor pressure sensor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of an example of a conventional semiconductor pressure sensor.

[Explanation of symbols]

1 ... Base, 2 ... Pedestal, 3 ... Pressure sensitive tip, 4 ... Lead wire, 5 ... External connection terminal, 6 ... Pressure guiding pipe, 7 ... Can, 8 ... Fluorosilicone gel.

Claims (1)

[Claims] 1. A diaphragm portion is formed on one surface of a semiconductor chip to reduce the thickness of a predetermined portion to form a diaphragm portion that can be deformed in response to pressure, and a strain gauge is formed on the other surface of the diaphragm portion. In the semiconductor pressure sensor of the structure in which the pressure of the measurement medium is applied to the one surface of the diaphragm portion of the pressure-sensitive chip formed, the hole size of the pressure introduction hole of the portion supporting the pressure-sensitive chip, A semiconductor pressure sensor is formed to have a size equal to or larger than a size of a recess forming the diaphragm part.