JPH0579938A - Semiconductor pressure sensor - Google Patents

Abstract

(57) [Summary] [Object] The present invention is capable of compensating for 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. To detect. [Structure] A pedestal tube 3 is joined to a lower surface of a semiconductor substrate 2, the semiconductor substrate 2 is used as a differential pressure sensor portion, and the semiconductor substrate 2 is arranged at a peripheral portion of the semiconductor substrate 2 and completely separated from the semiconductor substrate 2. The floating pedestal tube 5, which is completely separated from the pedestal tube 3, is joined to the lower surface of the semiconductor substrate 4, and the semiconductor substrate 4 is used as a static pressure sensor unit.

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. 4 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 on the side opposite to the surface on 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. 5, 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, the static pressure sensor used in such a semiconductor pressure sensor 100 has the same positional relationship on the same substrate as the differential pressure sensors 104 to 106 in order to share the influence on the temperature. Since it is located in the static pressure sensor, the differential pressure distortion also affects the static pressure sensor, and its response characteristics often do not give a unique signal. Since it is necessary to make a correction based on the output of the pressure sensor, an extremely troublesome correction relationship is 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 first semiconductor substrate made of, and one end of which is joined so as to surround the cavity formed on the first surface of the first semiconductor substrate and which has a pressure guiding path for introducing a pressure to be detected into the cavity. A pedestal tube, and 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; A second semiconductor substrate, which has a first surface and a second surface and is made of a single crystal semiconductor material, is arranged around the first semiconductor substrate, and one end thereof is bonded to the first surface of the second semiconductor substrate. Pedestal tube and the second
At least one vertical static pressure sensor and at least one parallel static pressure sensor formed on the second surface of the semiconductor substrate on the opposite side of the portion joined to the floating pedestal tube. It is characterized by

[0016]

In the above structure, a pedestal tube is joined to the lower surface of the first semiconductor substrate, the first semiconductor substrate is used as a differential pressure sensor section, and it is arranged in the peripheral portion of the first semiconductor substrate.
And by using the second semiconductor substrate as a static pressure sensor unit by joining the floating pedestal tube completely separated from the pedestal tube to the lower surface of the second semiconductor substrate completely separated from the first semiconductor substrate. The signals generated under static pressure and differential pressure are detected and compensated for, and the static pressure and 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.

The semiconductor pressure sensor 1 shown in this figure is a thin rectangular semiconductor substrate 2, a pedestal tube 3 bonded to one surface of the semiconductor substrate 2, and a mouth-shaped semiconductor arranged separately around the semiconductor substrate 2. It is composed of a substrate 4 and a floating pedestal tube 5 connected to one surface of the semiconductor substrate 4.

The semiconductor substrate 2 is composed of a rectangular substrate 6 made of a single crystal material such as silicon, and a rectangular shape is provided on the lower side (lower side in the figure) of the central portion of the semiconductor substrate 2. A thin diaphragm portion 8 formed by forming the recess 7 is formed, and impurities such as boron are diffused and injected into the upper side of the diaphragm portion 8 (the upper side in FIG. 1) as shown in FIG. Differential pressure sensors 9 to 12 having a desired shape and having a piezo characteristic are formed integrally with the substrate 2.

In this case, in the differential pressure sensors 9 to 12, the differential pressure sensors 9 and 10 are arranged in one crystal axis direction, and the other differential pressure sensors 11 and 12 are arranged in a direction orthogonal to the crystal axis direction. It is arranged.

When the diaphragm portion 8 is distorted by the pressure difference between the upper surface side and the lower surface side of the diaphragm portion 8, each of the differential pressure sensors 9 to 12 is corresponding to the distortion.
Changes its resistance value and is output to the outside as a differential pressure detection signal.

The pedestal tube 5 is made of Pyrex glass or the like, the outer diameter of which is approximately the same as the length of one side of the semiconductor substrate 2, and the inner diameter of which is approximately the same as the diameter of the recess 7. Is formed by a square tubular member 13 whose upper end (upper end in FIG. 1) is joined to the periphery of the lower surface of the semiconductor substrate 2 and the semiconductor is formed by a pressure guiding path 14 having a circular cross section formed therein. The pressure medium to be detected is guided into the recess 7 of the substrate 6.

The semiconductor substrate 4 is composed of a mouth-shaped substrate 15 made of a single crystal material such as silicon. Impurities such as boron are diffused and injected into the upper side (upper side in FIG. 1) of the semiconductor substrate 4. Then semiconductor substrate 4
The static pressure sensors 16 to 19 having a desired shape and having a piezo characteristic are integrally formed.

In this case, in each of the static pressure sensors 16 to 19, the static pressure sensors 16 and 17 are arranged in one crystal axis direction,
The other static pressure sensors 18 and 19 are arranged in a direction orthogonal to the crystal axis direction.

When the semiconductor substrate 4 is distorted by the static pressure of the portion in which the semiconductor substrate 4 is housed,
The resistance value of each of the static pressure sensors 16 to 19 changes according to this distortion, and this is output to the outside as a static pressure detection signal.

The floating pedestal tube 5 is made of Pyrex glass or the like, and its outer diameter is formed to be approximately the same as the length of one side forming the outer edge of the semiconductor substrate 4, and its inner diameter is the semiconductor substrate. It is constituted by a square tubular member 20 formed to have a length substantially equal to the length of one side forming the inner edge of 5, and its upper end (upper end in FIG. 1) is joined to the lower surface of the semiconductor substrate 4.

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

First, the semiconductor substrate 4 arranged around the semiconductor substrate 2 on which the diaphragm portion 8 is formed.
In addition, since the floating pedestal 5 such as Pyrex glass, which is a different material, is joined to the semiconductor substrate 4, the compression ratio is zero when the differential pressure applied to the diaphragm portion 8 is zero and only static pressure is applied. Since a large strain is likely to be transmitted from the floating pedestal 5 side having a large number to the semiconductor substrate 4 having a small compressibility, the strain induced on the upper surface (upper surface in the drawing) side of the semiconductor substrate 4 is larger than the strain induced on the diaphragm portion 8. Quite big.

On the other hand, the semiconductor substrate 2 on which the differential pressure sensors 9 to 12 are formed and the semiconductor substrate 4 on which the static pressure sensors 16 to 19 are formed are completely separated and the semiconductor substrate 2 is bonded. Pedestal tube 3 and the semiconductor substrate 4
Since the floating pedestal tube 5 to which is bonded is completely separated, the strain induced on the diaphragm surface by the differential pressure applied to both surfaces of the diaphragm portion 8 is generated from the semiconductor substrate 2 on which the diaphragm portion 8 is formed. It is extremely difficult to reach the upper surface of the semiconductor substrate 4 side.

As a result, the static pressure sensors 16 to 19 which mainly detect the 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 9 to 12 in one set mainly detect the differential pressure applied to the diaphragm portion 8, and the four static pressure sensors 16 to 19 in another set. Outputs a signal generated only by a change in static pressure applied to the semiconductor substrate 4 and the floating pedestal tube 5, the static pressure sensors 16 to 19
The differential pressure sensor 9 to 1 according to the static pressure detection signal output from the
By correcting the differential pressure detection signal output from 2,
The static pressure error signal component included in the outputs of the differential pressure sensors 9 to 12 can be removed.

As described above, in this embodiment, the pedestal tube 3 made of Pyrex glass or the like is joined to the lower surface of the central portion of the semiconductor substrate 2 and this portion is used as the differential pressure sensor section. A semiconductor substrate 4 completely separated from the semiconductor substrate 2 is arranged in the peripheral portion of the substrate 2, and a floating pedestal tube 5 made of Pyrex glass or the like is bonded to the lower surface of the semiconductor substrate 4 to form this portion. Since it is used as a static pressure sensor, it is possible to compensate for signals generated under static pressure and differential pressure, and at the same semiconductor substrate, the static pressure and differential pressure are extremely accurate and highly reliable. Can be detected with.

Further, in the above-described embodiment, the semiconductor substrate 2 and the pedestal tube 3 have a square outer edge, and the semiconductor substrate 4 arranged around the semiconductor substrate 2 and the pedestal tube 3.
Although the floating pedestal tube 5 has a mouth-shaped cross section, the semiconductor substrate 2 and the pedestal tube 3 have circular outer edges as shown in FIG. The inner edges of 4 and the floating pedestal tube 5 may be circular.

[0034]

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 plan view showing another embodiment of the semiconductor pressure sensor according to the present invention.

FIG. 4 is a cross-sectional view showing an example of a conventionally known semiconductor pressure sensor.

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

[Explanation of symbols]

 2 semiconductor substrate (first semiconductor substrate) 3 pedestal pipe 4 semiconductor substrate (second semiconductor substrate) 5 floating pedestal pipe 7 cavity 9 and 10 vertical differential pressure sensor 11 and 12 parallel differential pressure sensor 14 pressure guide path 16 , 17 Vertical static pressure sensor 18, 19 Parallel static pressure sensor

Claims (1)

[Claims] 1. A first semiconductor substrate made of a single crystal semiconductor material having a first surface and a second surface and having a cavity formed in the first surface; and a first semiconductor substrate formed on the first surface of the first semiconductor substrate. A pedestal tube having a predetermined shape, one end of which is joined so as to surround the cavity, and which has a pressure guiding path for introducing a pressure to be detected into the cavity; and the cavity on the second surface of the first semiconductor substrate. Having at least one vertical differential pressure sensor and at least one parallel differential pressure sensor formed on the opposite side of the first surface, and having a first surface and a second surface, and arranged around the first semiconductor substrate. A second semiconductor substrate made of a single crystal semiconductor material, a floating pedestal tube having one end bonded to a first surface of the second semiconductor substrate, and the floating pedestal tube on the second surface of the second semiconductor substrate. At least formed on the opposite side of the portion joined to A semiconductor pressure sensor, wherein number of the static pressure sensor in the vertical direction of the static pressure sensor and at least one parallel, further comprising: a.