JPH0579937A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To compensate the signals generated under the static pressure and the differential pressure and very precisely detect the static pressure and the differential pressure on the same semiconductor board with high reliability. CONSTITUTION:A semiconductor board 2 is connected at the center portion on one end side of one pedestal pipe 4, and pressure is guided to a cavity 6 formed on the lower side of the semiconductor board 2 via a pressure guide path 18 formed in the pedestal pipe 4 for use as a differential pressure sensor section. A semiconductor board 3 completely separated from the semiconductor board 2 is connected at the peripheral portion on one end side of the pedestal pipe 4, and the semiconductor board 3 is used as a static pressure sensor section.

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 for detecting pressure, and more particularly to a semiconductor pressure sensor capable of detecting signals generated under static pressure and differential pressure to detect static pressure and differential pressure with extremely high accuracy. Regarding sensors.

[0002]

2. Description of the Related Art Conventionally, a semiconductor pressure sensor has been known as one of sensors for detecting pressure.

This semiconductor pressure sensor utilizes the excellent elasticity of a single crystal semiconductor (eg, silicon) to detect the stress in response to the pressure difference applied to both ends of the thin film silicon diaphragm.

FIG. 3 is a sectional view showing an example of such a semiconductor pressure sensor.

The semiconductor pressure sensor 100 shown in FIG.
The concave portion 1 is formed on one surface of the silicon single crystal substrate 101 having the shaped surface.
02 to form a thin diaphragm portion 103, and p-type impurities are diffused on the surface opposite to the surface of the concave portion 102 side to form differential pressure sensors (strain gauge resistors) 104 to 106 as shown in FIG. After that, these differential pressure sensor 1
An oxide film 107 is formed on the surface of the single crystal substrate 101 on which 04 to 106 are formed to coat each of the differential pressure sensors 104 to 106, and further, the holes 108 are provided through the oxide film 107. It is formed by connecting the electrode layers 109 to both ends of each of the differential pressure sensors 104 to 106,
The electrode layer 109 is fixed to a pedestal tube 112 formed in a cylindrical shape, and the electrode layer 109 is connected to an external terminal (not shown) by a wire 110 formed of a gold wire or the like for use.

In FIG. 4, the electrode layer 109 is provided only on the right side of the differential pressure sensors 104 to 106, but in reality, the electrode layer 109 is provided for each of the differential pressure sensors 104 to 106. ing.

In the semiconductor pressure sensor 100 thus constructed, when the diaphragm portion 103 receives stress due to pressure, it is predetermined among the differential pressure sensors 104 to 106 formed on the surface of the diaphragm portion 103. The resistance value of the one arranged in the crystal axis direction increases and the resistance value of the other one arranged in the predetermined crystal axis direction decreases, so that each of the differential pressure sensors 104 to 1
The output voltage of the Wheatstone bridge circuit (not shown) constituted by 06 changes, and the detection signal corresponding to this change is output.

[0008]

However, in such a semiconductor pressure sensor 100, an erroneous signal called zero shift is generated even under static pressure (common pressure applied to both sides of the diaphragm).

Therefore, as a method for solving such a problem, a static pressure is detected using a pressure sensor different from the semiconductor pressure sensor 100, and the output of the semiconductor pressure sensor 100 is corrected based on the detection result. The method is done.

However, in such a method, two elements must be used. Therefore, if possible, a single type element should be used to generate two signals by simple correction from two signals. It is desirable to do.

Therefore, as a method of satisfying such requirements, the surface of the silicon single crystal substrate 101 (the pedestal tube 11
2 to the surface opposite to the surface to be joined to 2).
A sensor (static pressure sensor) for detecting strain caused by static pressure is provided in the same arrangement as 106, and the outputs of the differential pressure sensors 104 to 106 are corrected based on the output of this static pressure sensor. ..

However, in the static pressure sensor used in such a semiconductor pressure sensor, in order to make the influence on temperature common, the static pressure sensor is statically arranged on the same substrate as the differential pressure sensors 104 to 106 so as to have the same arrangement positional relationship. Since the pressure sensor is arranged, the static pressure sensor is also affected by the differential pressure distortion, and its response characteristics often do not become a unique signal. , Because it is necessary to make corrections based on the output of the differential pressure sensor,
An extremely troublesome correction relationship was necessary.

Therefore, in the method of correcting the signal of the differential pressure sensor by the static pressure sensor, there is a risk of giving an extremely large error.

In view of the above circumstances, the present invention is capable of compensating signals generated under static pressure and differential pressure, and the static pressure and differential pressure are on the same semiconductor substrate with extremely high accuracy and high reliability. An object of the present invention is to provide a semiconductor pressure sensor capable of detecting.

[0015]

In order to achieve the above object, a semiconductor pressure sensor according to the present invention has a first surface and a second surface, and a single crystal semiconductor material having a cavity formed in the first surface. And a second semiconductor substrate made of a single crystal semiconductor material having a first surface and a second surface and arranged around the first semiconductor substrate, and one end of which is the first semiconductor substrate. A predetermined shape that is joined to the first surfaces of the first and second semiconductor substrates so as to surround the cavity formed in the first surface and has a pressure guiding path that introduces a pressure to be detected into the cavity. A pedestal tube, at least one vertical differential pressure sensor and at least one parallel differential pressure sensor formed on the opposite side of the cavity on the second surface of the first semiconductor substrate; 2 The second of the semiconductor substrate
It is characterized in that it is provided with at least one vertical static pressure sensor and at least one parallel static pressure sensor formed on the side opposite to the one end joined to the pedestal pipe.

[0016]

In the above structure, the first semiconductor substrate is joined to the central portion on one end side of one pedestal tube and is formed on the lower surface side of the first semiconductor substrate through the pressure guiding path formed in the pedestal tube. It is used as a differential pressure sensor by guiding pressure to the hollow
Further, by bonding the second semiconductor substrate completely separated from the first semiconductor substrate to the peripheral portion of the pedestal tube on the one end side and using the second semiconductor substrate as the static pressure sensor unit, it is possible to reduce static pressure and difference. The signal generated under pressure is compensated, and the static pressure and the differential pressure are detected on the same semiconductor substrate with extremely high accuracy and high reliability.

[0017]

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

A semiconductor pressure sensor 1 shown in this figure has a thin rectangular semiconductor substrate 2 and a mouth-shaped semiconductor substrate 3 arranged around the semiconductor substrate 2 so as to be separated from the semiconductor substrate 2.
And a pedestal tube 4 joined to one surface of each of these semiconductor substrates 2 and 3.

The semiconductor substrate 2 is composed of a rectangular substrate 5 made of a single crystal material such as silicon, and a rectangular concave portion is located below the central portion of the semiconductor substrate 2 (lower side in FIG. 1). 6 is formed, a thin diaphragm portion 7 is formed, and as shown in FIG. 2, impurities such as boron are injected into the upper side (upper side in FIG. 1) of the diaphragm portion 7 by diffusion to form the substrate 5 and Differential pressure sensor 8 of desired shape having piezo characteristics integrally formed
11 is formed.

In this case, the differential pressure sensors 8 to 11 are arranged such that the differential pressure sensors 8 and 9 are arranged in one crystal axis direction, and the other differential pressure sensors 10 and 11 are arranged in a direction orthogonal to the crystal axis direction. It is arranged.

When the diaphragm portion 7 is distorted by the pressure difference between the upper surface side and the lower surface side of the diaphragm portion 7, each of the differential pressure sensors 8 to 11 corresponding to the distortion.
Changes its resistance value and is output to the outside as a differential pressure detection signal.

The semiconductor substrate 3 is composed of a mouth-shaped substrate 12 made of a single crystal material such as silicon. As shown in FIG. 2, boron or the like is provided above the semiconductor substrate 3 (upper side in FIG. 1). The static pressure sensors 13 to 16 having a desired shape with piezoelectric characteristics are formed integrally with the semiconductor substrate 3 by diffusing and injecting the impurities.

In this case, in each of the static pressure sensors 13 to 16, the static pressure sensors 13 and 14 are arranged in one crystal axis direction,
The other static pressure sensors 15 and 16 are arranged in a direction orthogonal to the crystal axis direction.

When the semiconductor substrate 3 is distorted by the static pressure of the portion in which the semiconductor substrate 3 is housed,
The resistance value of each of the static pressure sensors 13 to 16 changes according to this distortion, and this is output as a static pressure detection signal.

The pedestal tube 4 is made of Pyrex glass or the like, and the outer diameter of the pedestal tube 4 is the same as the length of one side forming the outer edge of the semiconductor substrate 3. The inner diameter of the pedestal tube 4 is the same as that of the recess 6. It is composed of a cylindrical member 17 having a circular cross section formed to be considerably shorter than its diameter, and its upper end (upper end in FIG. 1) is joined to the lower surface of each of the semiconductor substrates 2 and 3, and the circular cross section formed inside thereof is formed. The pressure medium to be detected is guided to the concave portion 6 of the semiconductor substrate 2 by the pressure guiding path 18.

Next, the structure, effect, and relationship of this embodiment will be described with reference to FIGS.

First, since the pedestal tube 4 such as Pyrex glass, which is a different material, is bonded to the semiconductor substrate 3 arranged around the semiconductor substrate 2 on which the diaphragm portion 7 is formed, the diaphragm portion is formed. When the differential pressure applied to 7 is zero and only static pressure is applied, a large strain is easily transmitted from the pedestal tube 4 side having a large compression rate to the semiconductor substrates 2 and 3 having a small compression rate. Tube 4
The strain induced on the upper surface side (the upper surface in FIG. 1) of the semiconductor substrate 3 immediately above the junction surface with is much larger than the strain induced on the diaphragm portion 7.

On the other hand, since the semiconductor substrate 2 on which the differential pressure sensors 8 to 11 are formed and the semiconductor substrate 3 on which the static pressure sensors 13 to 16 are formed are completely separated from each other, both sides of the diaphragm portion 7 are separated. The strain induced on the diaphragm surface by the differential pressure applied to the semiconductor substrate 3 is completely separated from the semiconductor substrate 2 on which the diaphragm portion 7 is formed.
It is extremely difficult to reach the upper surface of the side.

As a result, the static pressure sensors 13 to 16 which mainly detect static pressure have a small error due to the differential pressure, and exhibit a unique error characteristic within the measuring range of the differential pressure.

As a result, the four differential pressure sensors 8 to 11 in one set mainly detect the differential pressure applied to the diaphragm portion 7, and the four static pressure sensors 13 to 16 in another set are detected. Since the signal generated only by the change in the static pressure applied to the semiconductor substrate 3 and the pedestal tube 4 is output, the signals output from the static pressure sensors 13 to 16 are corrected to correct the signals output from the differential pressure sensors 8 to 11. , The differential pressure sensor 8 to
The static pressure error signal component included in the output of 11 can be removed.

As described above, in this embodiment, the pedestal tube 4 made of Pyrex glass or the like is joined to the lower surface of the central portion of the semiconductor substrate 2 and the semiconductor substrate 2 is used as the differential pressure sensor section 7. A semiconductor substrate 3 which is completely separated from the semiconductor substrate 2 is arranged in the peripheral portion of the semiconductor substrate 2, and the lower surface of the semiconductor substrate 3 is joined to the pedestal tube 4 to fix the semiconductor substrate 3 to the static pressure sensor unit. Since it is used as, it is possible to compensate signals generated under static pressure and differential pressure, and to detect static pressure and differential pressure on the same semiconductor substrate with extremely high accuracy and high reliability. it can.

Further, in the above-mentioned embodiment, the outer edges of the respective semiconductor substrates 2 and 3 are made square, and the pedestal tube 4 having a circular outer edge is joined to the lower surface side thereof. Even if other shapes, for example, the outer edge shapes of the semiconductor substrates 2 and 3 are circular and the pedestal tube 4 joined thereto is cylindrical, the same effect as the above-described embodiment can be obtained.

[0033]

As described above, according to the present invention, signals generated under static pressure and differential pressure can be compensated, and the static pressure and differential pressure can be compensated on the same semiconductor substrate with extremely high accuracy. It can be detected with high reliability.

[Brief description of drawings]

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

FIG. 2 is a plan view of the semiconductor pressure sensor shown in FIG.

FIG. 3 is a sectional view showing an example of a conventionally known semiconductor pressure sensor.

FIG. 4 is a plan view of the semiconductor pressure sensor shown in FIG.

[Explanation of symbols]

 2 semiconductor substrate (first semiconductor substrate) 3 semiconductor substrate (second semiconductor substrate) 4 pedestal tube 6 cavity 8 and 9 vertical direction differential pressure sensor 10 and 11 parallel direction differential pressure sensor 13 and 14 vertical direction static pressure sensor 15, 16 Parallel static pressure sensor 18 Pressure guide path

Claims (1)

[Claims] 1. A first semiconductor substrate having a first surface and a second surface and made of a single crystal semiconductor material in which a cavity is formed in the first surface; a first semiconductor substrate having a first surface and a second surface; A second semiconductor substrate made of a single crystal semiconductor material is disposed around the first semiconductor substrate, and the first and the second semiconductor substrates are formed so that one end thereof surrounds the cavity formed in the first surface of the first semiconductor substrate. 2 A pedestal tube having a predetermined shape, which is joined to each first surface of the semiconductor substrate and has a pressure guiding path for introducing a pressure to be detected into the cavity, and the second surface of the first semiconductor substrate opposite the cavity. At least one vertical differential pressure sensor and at least one parallel differential pressure sensor formed on the side, and the second surface of the second semiconductor substrate opposite to one end joined to the pedestal tube. At least one vertical static pressure sensor A semiconductor pressure sensor, wherein the static pressure sensor of at least one parallel, further comprising a called.