JP2859982B2 - Semiconductor pressure sensor - Google Patents

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 having a tilt sensor for compensating for a signal generated under a static pressure and a differential pressure and for compensating an error due to a tilt of the sensor itself. And a semiconductor pressure sensor capable of detecting a differential pressure with extremely high accuracy.

[0002]

2. Description of the Related Art A semiconductor pressure sensor is conventionally known as one of sensors for detecting pressure.

This semiconductor pressure sensor utilizes the excellent elasticity of a single crystal semiconductor (for example, silicon) to detect a stress responsive to a pressure difference between both ends of a thin-film silicon diaphragm and to respond to the magnitude of the stress. Output pressure detection signal of value.

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

The semiconductor pressure sensor 100 shown in FIG.
A concave portion 1 on one surface of a silicon single crystal substrate
02 is formed into a thin diaphragm portion 103, and a p-type impurity is diffused on the surface opposite to the surface on the side of the concave portion 103 to form a plurality of differential pressure sensors (strain gauge resistors) 104 to 106 as shown in FIG. Then, an oxide film 107 is formed on the surface of the single crystal substrate 101 on which the differential pressure sensors 104 to 106 are formed, and
6 and through each of the differential pressure sensors 104 to 104 through holes 108 provided through the oxide film 107.
An electrode layer 109 is formed by connecting the electrode layer 109 to both ends of the electrode layer 106. The electrode layer 109 is fixed to a pedestal tube 112 formed in a cylindrical shape. (Not shown)
Is used by being connected.

In FIG. 4, although the electrode layer 109 is connected only to the differential pressure sensors 104 to 106 on the right side, the electrode layer 109 is actually provided for each of the differential pressure sensors 104 to 106. Have been.

In the semiconductor pressure sensor 100 configured as described above, when the diaphragm 103 is subjected to stress by pressure, a predetermined one of the differential pressure sensors 104 to 106 formed on the surface of the diaphragm 103 is determined. The resistance value of one of the differential pressure sensors 104 to 1 is increased while the resistance value of another of the differential pressure sensors 104 to 1 is decreased while the resistance value of the other one is decreased.
The output voltage of a Wheatstone bridge circuit (not shown) constituted by the reference numeral 06 changes, and a detection signal corresponding to the change is output.

[0008]

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

Therefore, as a method for solving such a problem, a static pressure is detected by using a pressure sensor separate from the semiconductor pressure sensor 100, and the output of the differential pressure sensors 104 to 106 is determined based on the detected value. Has been put to practical use.

However, in such a method, since two elements must be used, it is preferable to use a single type element and perform two signal corrections only by performing simple correction on the two signals. It is desirable to obtain

Therefore, as a method for satisfying such a demand, the surface of the silicon single crystal substrate 101 (the pedestal tube 11) is used.
2), the differential pressure sensor 104
A sensor (static pressure sensor) for detecting a distortion caused by a static pressure is provided in the same arrangement as that of the differential pressure sensors 104 to 106, and the outputs of the differential pressure sensors 104 to 106 are corrected based on the output of the static pressure sensor. I have.

However, in such a semiconductor pressure sensor 100, in order to make the influence on the temperature common, the static pressure sensors are arranged on the same substrate as the differential pressure sensors 104 to 106 and in the same arrangement positional relationship. So
The effect of the differential pressure distortion is exerted on the static pressure sensor, and the response characteristic of the static pressure sensor often does not become a unique signal.
Since it is necessary to perform correction based on the output of No. 06, an extremely troublesome correction relationship was required.

Therefore, in such a method of correcting the signals of the differential pressure sensors 104 to 106 using such a static pressure sensor,
An extremely large error may occur.

Further, such a semiconductor pressure sensor 100
In this case, when the semiconductor pressure sensor 100 is put in a case, the diaphragm 10
The weight of the pressure medium (for example, silicone oil) filled so as to surround the third differential pressure sensors 104 to 106 is applied to the differential pressure sensors 104 to 106 and output from the differential pressure sensors 104 to 106. Since the error component due to the inclination of the sensor itself is superimposed on the signal, the correction of each of the differential pressure sensors 104 to 106 may become considerably difficult.

Further, depending on the installation conditions of the semiconductor pressure sensor 100, when measuring the differential pressure in an environment accompanied by a low-frequency signal, noise caused by vibration causes the differential pressure sensor 104 to measure.
In some cases, an error occurs in the outputs of to 106, and the development of a semiconductor pressure sensor that can remove such noise is strongly desired.

In view of the above circumstances, the present invention can compensate for signals generated under static pressure and differential pressure, and can perform static pressure and differential pressure on the same semiconductor substrate with extremely high accuracy and high reliability. It is an object of the present invention to provide a semiconductor pressure sensor capable of detecting the pressure.

[0017]

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 cavity is formed in a central portion of the first surface.
A semiconductor substrate of a predetermined shape made of a single crystal semiconductor material having a plurality of holes formed in a periphery surrounding the cavity from a second surface to a first surface and a beam connecting the central portion and the peripheral portion formed; A pedestal tube having a predetermined shape, one end of which is joined so as to surround the cavity formed on the first surface of the semiconductor substrate and guides a pressure medium to be detected to the cavity by a pressure guiding path formed inside; A floating pedestal tube made of a material different from that of the semiconductor substrate, one end of which is joined to a first surface on the outermost periphery of the semiconductor substrate; and a floating pedestal tube formed on the second surface of the semiconductor substrate on the opposite side of the cavity. At least one or more vertical differential pressure sensors and at least one
One or more parallel direction differential pressure sensors, at least one or more vertical static pressure sensors formed at a portion of the semiconductor substrate joined to the floating pedestal tube, and at least one or more parallel direction static pressure sensors It is characterized by comprising a static pressure sensor and at least one or more inclination sensors formed on the second surface of the beam.

[0018]

In the above construction, a pedestal tube is connected to the lower surface of the central portion of the semiconductor substrate, and this portion is used as a differential pressure sensor. A floating pedestal tube separated from the pedestal tube is provided around the semiconductor substrate. The peripheral portion of the semiconductor substrate is connected and used as a static pressure sensor portion, and the differential pressure sensor portion and the static pressure sensor portion are connected by a beam to incline between the central portion and the peripheral portion of the semiconductor substrate. When used as a sensor section, signals generated under static pressure and differential pressure are compensated, and static pressure and differential pressure are detected on the same semiconductor substrate with extremely high accuracy and high reliability.

[0019]

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

The semiconductor pressure sensor shown in FIG. 1 has a thin rectangular semiconductor substrate 1, a pedestal tube 2 connected to one surface of the semiconductor substrate 1, and a pedestal tube 2 disposed around the pedestal tube 2. Floating pedestal tube 3 to be joined.

The semiconductor substrate 1 is constituted by a rectangular substrate 4 made of a single crystal material such as silicon, and is divided into a differential pressure sensor section 5, an inclination sensor section 6, and a static pressure sensor section 7. Have been.

The differential pressure sensor section 5 has a thin diaphragm section 9 formed by forming a rectangular recess 8 below the central portion of the semiconductor substrate 1 (the lower side in FIG. 1), and as shown in FIG. An impurity such as boron is diffused and injected into the upper side of the diaphragm section 9 (upper side in FIG. 1), and the differential pressure sensor 1 having a desired shape and having piezo characteristics is formed integrally with the semiconductor substrate 1.
0 to 13 are provided.

In this case, the differential pressure sensors 10 to 13 are formed so that the differential pressure sensors 10 and 11 coincide with a predetermined crystal axis direction.
3 are formed so as to be orthogonal to the crystal axis.

When the diaphragm 9 is distorted by the pressure difference between the upper surface and the lower surface of the diaphragm 9, the differential pressure sensors 10-1
The resistance value of No. 3 changes and is output to the outside as a differential pressure detection signal.

The tilt sensor section 6 is provided on the semiconductor substrate 1.
Of the differential pressure sensor section 5 (the lower side in the figure)
A plurality of beam portions 17 formed by forming a plurality of holes 16 in required portions of a thin portion 15 formed by forming a frame-shaped long groove 14
And an inclination sensor 18 to 21 having a desired shape and having piezo characteristics formed integrally with the semiconductor substrate 1 by diffusing and implanting an impurity such as boron above each of the beam portions 17 (upper side in FIG. 1). ing.

In this case, the inclination sensors 18 to 21 are arranged such that when the semiconductor pressure sensor is housed in a case, the inclination sensors 18 and 19 are in an up-down relationship and the inclination sensors 20 and 21 are in an up-down relationship. 17 is formed.

When the relative position of the static pressure sensor section 7 with respect to the differential pressure sensor section 5 changes and each beam section 17 is distorted, the resistance value of each of the tilt sensors 18 to 21 changes in accordance with the distortion. And this is output to the outside as an inclination detection signal.

The static pressure sensor 7 is provided on the semiconductor substrate 1.
An opening-shaped frame portion 22 formed around the upper tilt sensor portion 6 and an impurity such as boron are diffused and implanted into the upper side (the upper side in FIG. 1) of the frame portion 22 as shown in FIG. 1 and static pressure sensors 23 to 26 having a desired shape and having piezo characteristics formed integrally therewith.

In this case, the static pressure sensors 23 to 26 are formed so that the static pressure sensors 23 and 24 coincide with a preset crystal axis direction, and the other static pressure sensors 25 and
6 are formed so as to be orthogonal to the crystal axis.

When each of the frame portions 22 is distorted by the static pressure in the case in which the semiconductor pressure sensor is housed, the resistance value of each of the static pressure sensors 23 to 26 changes according to the distortion. It is output to the outside as a static pressure detection signal.

The pedestal tube 2 is made of Pyrex glass or the like. The outer diameter of the pedestal tube 2 is longer than the length of one side of the concave portion 8 constituting the differential pressure sensor section 5 and the inner diameter thereof is one side of the concave portion 8. It is constituted by a rectangular tube member 27 formed so as to be much shorter than the length, and the upper end (the upper end in the figure) is joined to the lower surface of the semiconductor substrate 1 constituting the differential pressure sensor section 5 and the inside thereof is formed. The pressure medium to be detected is guided to the concave portion 8 of the differential pressure sensor section 5 by the formed pressure guiding path 28 having a circular cross section.

The floating pedestal tube 3 is made of Pyrek glass or the like, the outer diameter of which is formed to be substantially the same as the length of one side constituting the outer edge of the static pressure sensor section 7, and the inner diameter of which is the same as the above. The static pressure sensor 7 is constituted by a square tubular member 29 having substantially the same length as one side constituting the inner edge of the static pressure sensor 7, and the upper end (the upper end in the figure) of the semiconductor constituting the static pressure sensor 7 It is joined to the lower surface of the substrate 1.

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

First, a floating pedestal 3 made of a different material, such as Pyrex glass, is bonded to the semiconductor substrate 1 around the lower surface of the semiconductor substrate 1. Since a large strain is easily transmitted to the substrate 1, when the pressure difference applied to the diaphragm portion 9 is zero and only the static pressure is applied, the semiconductor substrate 1 just above the bonding surface between the semiconductor substrate 1 and the floating pedestal tube 3 is formed. 1 is considerably larger than the strain induced in the diaphragm portion 9.

On the other hand, the strain generated in the diaphragm portion 9 of the differential pressure sensor portion 5 due to the long groove 14 provided on the lower surface side (the lower surface side in FIG. 1) of the inclination sensor portion 6 and the plurality of holes 16 causes Since the transmission to the static pressure sensor portion 7 formed on the semiconductor substrate 1 is extremely difficult, even if a strain is induced on the diaphragm surface by the differential pressure applied to both surfaces of the diaphragm portion 9, the static pressure sensors 23 to 26 The output hardly changes.

Therefore, each of the static pressure sensors 23 to 26 for mainly detecting the static pressure has a small error due to the differential pressure, and exhibits a unique error characteristic within the differential pressure measurement range.

As a result, one set of four differential pressure sensors 10 to 13 mainly detects the differential pressure applied to the diaphragm section 9 and the other set of four static pressure sensors 23 to 2.
6 outputs a signal generated only by a change in the static pressure applied to the semiconductor substrate 1 and the floating pedestal tube 3, so that the static pressure sensor 23
Pressure sensors 10-1 by signals output from
The static pressure error signal component included in the outputs of the differential pressure sensors 10 to 13 can be removed by correcting the signal output from the third pressure sensor 3.

Further, when the semiconductor substrate 1 is fixed to the pedestal tube 2 and a force due to inclination or a force due to vibration is applied to the semiconductor substrate 1, the diaphragm portion 9 is thereby formed.
And the signals output from the four differential pressure sensors 10 to 13 change. At this time, the relative position of the static pressure sensor unit 7 with respect to the differential pressure sensor unit 5 changes, and these are connected. Each of the beam sections 17 of the tilt sensor section 6 is distorted, and the four tilt sensors 18 to 21 provided on each of the beam sections 17 are distorted.
Changes from the signals output from the inclination sensors 18 to 21, the signals output from the inclination sensors 18 to 21 change.
By correcting the signals output from the differential pressure sensors 10 to 13, the tilt error signal component and the vibration error signal component included in the outputs of the differential pressure sensors 10 to 13 can be removed.

As described above, in this embodiment, the pedestal tube 2 is connected to the lower surface of the central portion of the semiconductor substrate 1 and this portion is used as the differential pressure sensor portion 5, and the pedestal tube 2 is attached to the peripheral portion of the semiconductor substrate 1. The floating pedestal pipe 3 separated from the pipe 2 is used as a static pressure sensor 7 by connecting the differential pressure sensor 5 and the static pressure sensor 7 by a plurality of beams 17 to connect this part. Since it is used as the tilt sensor unit 6, it is possible to compensate for signals generated under static pressure and differential pressure, and to perform static pressure and differential pressure on the same semiconductor substrate with extremely high accuracy and high reliability. Can be detected.

In the above embodiment, the cross sections of the semiconductor substrate 1, the pedestal tube 2, and the floating pedestal tube 3 are square, but they may be circular or polygonal. Further, the shape of the hole 16 formed in the inclination sensor unit 6 may be changed to another shape.

[0041]

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 controlled on the same semiconductor substrate with very high accuracy. It can be detected with high reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one 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 cross-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. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Pedestal pipe 3 Floating pedestal pipe 5 Differential pressure sensor part 6 Inclination sensor part 7 Static pressure sensor part 8 Recess (cavity) 10, 11 Differential pressure sensor (vertical direction differential pressure sensor) 12, 13 Differential pressure sensor (parallel) Directional pressure difference sensor) 16 holes 17 beams 18-21 Inclination sensor 23, 24 Static pressure sensor (vertical static pressure sensor) 25, 26 Static pressure sensor (parallel static pressure sensor) 28 Pressure guiding path

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tadahiro Hayashi 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant Co., Ltd. (72) Inventor Taichi Watanabe 1-Toshiba-cho, Fuchu-shi Tokyo (72) Inventor Akira Ishii 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu Plant, Toshiba Corporation (56) References JP-A-2-64430 (JP, A) JP-A-4-113239 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G01L 9/04 101 G01L 13/06

Claims (1)

(57) [Claims] A first surface having a first surface and a second surface, a cavity formed in a central portion of the first surface, and a plurality of holes penetrating from the second surface to the first surface around the cavity. A semiconductor substrate of a predetermined shape formed of a single crystal semiconductor material and formed with a beam connecting the central portion and the peripheral portion, one end of which surrounds the cavity formed in the first surface of the semiconductor substrate; A pedestal tube of a predetermined shape for guiding a pressure medium to be detected into the cavity by a pressure guiding path formed inside by being joined to, a material different from the semiconductor substrate, and one end of the pedestal tube at the outermost periphery of the semiconductor substrate A floating pedestal tube joined to a first surface, at least one or more vertical differential pressure sensors and at least one or more parallel differential pressure formed on the second surface of the semiconductor substrate on the opposite side of the cavity. A sensor and the half At least one or more vertical static pressure sensors and at least one or more parallel static pressure sensors formed on a portion of the body substrate joined to the floating pedestal tube on the second surface, and a second surface of the beam And at least one or more inclination sensors formed in the semiconductor pressure sensor.