JPH10300602A - Semiconductor pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply at low price a semiconductor pressure sensor capable of measuring pressure from a low pressure region to a high pressure region with high precision and excellent pressure-resistance. SOLUTION: A silicon chip has a single diaphragm 16 forming on the face a set of bridge circuits comprising a boss 17, a stopper 18 and a semiconductor distortion gauge 20, and is joined to a pedestal. When a diaphragm is deformed in response to an applied pressure, the stopper 18 is brought into contact with the pedestal by a predetermined pressure. This pressure sensor is set to have a signal processing circuit capable of respectively with high precision detecting a pressure in a low pressure region before the stopper 18 is brought into contact with the pedestal and a pressure in a high pressure region after the stopper is brought into contact with the pedestal. Thereby, it is possible to provide a semiconductor pressure sensor at low cost and in a wide measurement range.

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, and more particularly, to a semiconductor pressure sensor used for a wide range of pressure measurement of liquids such as fuel, oil, and oil pressure. The present invention relates to pressure sensors that detect with high accuracy.

[0002]

2. Description of the Related Art As a prior art relating to the present invention, for example, Japanese Patent Application Laid-Open Nos. 3-112168 and 4-178533 are known. In order to detect the pressures in the low pressure region and the high pressure region with high accuracy, a diaphragm for detecting a low pressure and a diaphragm for detecting a high pressure are provided, and a bridge circuit formed of a semiconductor strain gauge is formed in each of the diaphragms. Basically, the pressure in the low pressure region and the pressure in the high pressure region are detected using separate diaphragms and signal processing circuits.

[0003]

However, since the construction of the pressure detecting section and the signal processing circuit are complicated and their sizes are large, there have been problems in productivity and cost reduction.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a low-cost pressure sensor having excellent pressure resistance and capable of measuring with high accuracy from a low pressure region to a high pressure region.

[0005]

Basically, a set of bridge circuits formed on one diaphragm detects the pressure in the low pressure region and the pressure in the high pressure region with high accuracy. A silicon chip having a diaphragm formed on the surface with a bridge circuit composed of a boss, a stopper and a semiconductor strain gauge is joined to a pedestal, and the diaphragm is deformed according to the applied pressure, and the stopper is brought into contact with the pedestal at a predetermined pressure. To do. A signal processing circuit that processes a signal corresponding to the pressure obtained from one set of bridge circuits. The signal processing circuit generates a pressure in a low-pressure region before the stopper contacts the pedestal and a pressure in a high-pressure region after the stopper contacts the pedestal. Get the corresponding output signal. By bringing the stopper into contact with the pedestal in the high pressure area, it is possible to improve the pressure resistance of the diaphragm when high pressure is applied, and to increase the sensitivity corresponding to the pressure in the low pressure area. Can be detected with high accuracy. Also,
Since the bridge circuit composed of the diaphragm and the semiconductor strain gauge is one set, the size of the detecting section is small and simple, and the productivity is improved. As a result, a low-cost semiconductor pressure sensor is obtained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is an overall configuration diagram of a semiconductor pressure sensor according to the present invention. SOI comprising first silicon substrate 1, thermal oxide film 2, and second silicon substrate 3
The substrate is hermetically bonded to the pedestal 4 made of Pyrex glass by anodic bonding. The pedestal 4 is adhered to a stem 6 welded to a housing 7 with a low-melting glass 5. The stem 6 made of a material such as Kovar has a lead pin 11
Are hermetically mounted with a glass member 12 having a high melting point. The pedestal 4 has a through hole 10 machined.
Solder 9 and lead pin 11 inserted in through hole 10
Is connected. The detection unit made of the SOI substrate is connected to the signal processing circuit 8 via the solder 9, the lead pin 11, and the conductor 13.
Is electrically connected to Note that elements having the same numbers, which will be described later, all have the same function.

FIG. 2 is a detailed sectional view of a detecting portion of the semiconductor pressure sensor according to the present invention. An SOI substrate in which the first silicon substrate 1 and the second silicon substrate 3 are directly bonded at a temperature of 1100 ° C. or higher via the thermal oxide film 2 is etched to form a diaphragm 16 and a boss 1 on the first silicon substrate 1.
7, a stopper 18, a semiconductor strain gauge 20, and a silicon pad 19 are formed on the second silicon substrate 3. The thicknesses of the first silicon substrate 1, the thermal oxide film 2, and the second silicon substrate 3 are about several hundred microns, 1 micron, and 10 microns, respectively.
Micron. A gap 21 is formed between the stopper 18 and the pedestal 4. The metal thin film 14 is formed on the silicon pad 19 on the bottom surface of the through hole 10 by a method such as sputtering or vapor deposition. Metal thin film 1
Reference numeral 4 denotes a multilayer film of Al / Ti / Ni / Au or the like, and the solder 9 is electrically connected to the silicon pad 19 via the metal thin film 14. The silicon pad 19 is separated from the outer frame of the second silicon substrate 3 by the groove 15. Here, the dimension of the diaphragm 16 is A, the dimension of the boss 17 is B, the dimension of the stopper 18 is C, the distance between the semiconductor strain gauges 20 is D, and the distance between the silicon pads 19 is E. When E ≧ A, the size of the diaphragm 16 is determined by A, and when E <A, the substantial size of the diaphragm 16 is determined by E.

FIG. 3 is a plan view of the second silicon substrate 3 as viewed from the pedestal 4 side. The four silicon pad portions 19 are separated from the outer frame portion 22 of the second silicon substrate 3 by the grooves 15. The metal thin film 14 is formed substantially at the center of the silicon pad 19. Two radial semiconductor strain gauges 2
0a and two tangential semiconductor strain gauges 20b are formed on the surface of the thermal oxide film 2, and the thermal oxide film 2 electrically connects the first silicon substrate 1 and the outer frame portion 22 of the second silicon substrate 3 to each other. Insulated. A bridge circuit is formed by these four semiconductor strain gauges, and is electrically connected to the silicon pad 19 via the lead lead-out part 23.
As shown in the previous figure, the stopper 18 is formed below the boss 17. 1st silicon substrate 1, 2nd silicon substrate 3
Is made of (100) P-type single crystal silicon, and the silicon pad 19 and the lead lead-out portion 23 are doped with boron to reduce the resistance of this portion. The thicknesses of the semiconductor strain gauges 20a and 20b and the lead lead-out portion 23 are about 0.5.
Designed to a value of 5-3.0 microns. Further, the thickness of the stopper 18 is processed so that the gap 21 described in the previous figure is about 1 micron.

FIG. 4 is a plan view of the SOI detector as viewed from the diaphragm side. A boss 17 is formed at the center of the diaphragm 16. The inclined portions 24 and 25 are generated when the diaphragm 16 and the boss 17 are etched with an alkaline solution. Further, the semiconductor strain gauges 20a,
20 b is not visible from the diaphragm 16 side, but is shown in the figure in the sense that it is located at that position below the diaphragm 16.

FIG. 5 shows an output characteristic example of the semiconductor pressure sensor according to the present invention. This figure shows the relationship between the output voltage Vo and the pressure P to be measured. Output characteristics (a)
Represents the signal generated in the bridge circuit as it is in the signal processing circuit 8
Amplified by This is an example in which the stopper 18 is brought into contact with the base 4 at a pressure of 1 Mpa. As shown in FIG.
The detection sensitivity of the low-pressure region of Mpa is different from that of the high-pressure region of 1 to 10 Mpa, and the sensitivity of the low-pressure region is about 10 times that of the high-pressure region.

If the sensitivity is increased within a range where the diaphragm 16 is not destroyed, the pressure can generally be detected with a higher degree of accuracy. As shown in the figure, since the sensitivity in the low pressure region is high, the detection accuracy of this portion is easily improved. Further, the change value of the output voltage in the low voltage range of 0 to 1 Mpa and the change value of the output voltage in the high voltage range of 1 to 10 Mpa are almost the same, and the detection accuracy in the high voltage region is also high. When the stopper 18 comes into contact with the pedestal 4, the size of the diaphragm 16 becomes equivalently small, and the pressure resistance of the diaphragm 16 itself improves. And
As shown in the figure, the sensitivity to a unit pressure change becomes smaller on the high pressure region side, and the output characteristic becomes stepped at a pressure of 1 Mpa. In a system using a semiconductor pressure sensor, a microcomputer is used, and such a step breaking characteristic does not cause any problem in a control system. If necessary, such a step-break characteristic (a) may be processed by the signal processing circuit 8 into a low-pressure region and a high- It is also easy to convert the output to the two-output characteristic of the area and output the output. In some cases, this is more convenient. Unless the arrangement of the semiconductor strain gauges 20a and 20b is devised, the signal generated in the bridge circuit has the (x) characteristic shown by the dotted line. In this case, the pressure has two values in the low pressure region and the high pressure region, and the pressure value cannot be discriminated. To avoid this, ΔVo / ΔP must be made positive instead of negative.

A method for avoiding the binary characteristic will be described with reference to FIG. This figure shows the magnitude of the unit signal change ΔVo of the bridge circuit with respect to the unit pressure change ΔP in the high pressure region after the stopper 18 contacts the pedestal 4.
As shown in the figure, the output sensitivity ΔV generated in the bridge circuit
o / ΔP is determined by the arrangement position of the semiconductor strain gauge, and the gauge position D / A (when E ≧ A) or D / E (E <A
) Is approximately 0.9, zero, below 0.9, negative, and above 0.9, positive. Therefore, setting the gauge position to at least 0.9 or more and setting it as close to 1.0 as possible has no binary value and can increase the sensitivity in the high-pressure region. That is, as much as possible the semiconductor strain gauge 20
It is desirable to arrange a and 20b near the fixed end of the diaphragm 16. Boss 17 dimension B, stopper 1
Depending on the value of the dimension C of 8, the gauge position at which the output sensitivity ΔVo / ΔP becomes zero is not necessarily 0.9, and moves to a slightly shifted position.

In some cases, it is desirable that the signal characteristics generated in the bridge circuit formed by the semiconductor strain gauge be non-linear over the entire pressure measurement range or partially.
The reason why the output characteristic is made nonlinear in advance is that it is effective to improve the accuracy of the read value in the entire pressure measurement range from the low pressure region to the high pressure region. FIG. 7 shows an output characteristic example in this case. The output characteristic (e) has a linear characteristic in a low pressure range of 0 to 1 Mpa and a non-linear characteristic in a high pressure range of 1 to 10 Mpa. On the other hand, the output characteristic (f) has non-linear characteristics in the entire region from the low pressure region to the high pressure region.

Next, a method for obtaining these output characteristics (e) and (f) will be described.

First, SOI for obtaining the output characteristic (e)
FIG. 8 shows a cross-sectional structure of the detection unit. The feature of this drawing is that there is no boss on the diaphragm 16 and the size of the stopper 18 is C
Is large. Naturally, the stopper 1
Low pressure area until 0 contacts base 4 (0 to 1 Mpa)
Is linear as shown in the previous figure.
Since the thickness of the stopper 18 is as thin as 10 μm or less, the elastic body composed of the diaphragm 16 and the stopper 18 is deformed like a bow as a whole. Thereafter, as the pressure increases, the contact position between the pedestal 4 and the stopper 18 gradually moves toward the end of the stopper 18 including the center of the stopper 18. As a result, the high pressure region (1 to 10
The output characteristic at Mpa) becomes nonlinear.

When the boss 17 is present as shown in FIG. 2, the elastic body composed of the boss 17, the diaphragm 16 and the stopper 18 moves in parallel to the pedestal 4 according to the pressure. As a result, as shown in the output characteristic (a) of FIG. 5, the output characteristic in the high pressure region (1 to 10 Mpa) becomes linear.

Next, the SOI for obtaining the output characteristic (f)
FIG. 9 shows a cross-sectional structure of the detection unit. The feature of this figure is that the stopper 18 is etched so that there is no boss on the diaphragm 16 and the center is thicker and thinner toward the end. Then, the SOI detector and the pedestal 4 made of Pyrex glass are bonded by anodic bonding so that the pressure value applied to the diaphragm 16 is zero and the stopper 18 contacts the pedestal 4. As a result, as the value of the pressure increases from 0 Mpa to 10 Mpa, the contact position between the stopper 18 and the pedestal 4 gradually and continuously moves from the central portion of the stopper 18 to the peripheral portion. Therefore, a non-linear output characteristic (f) is continuously obtained from the low pressure region to the high pressure region. As the contact portion moves from the center of the stopper 18 to the periphery, the stress is equivalent to a decrease in the size of the diaphragm. Therefore, an output characteristic (f) is obtained in which the lower the pressure, the higher the sensitivity, and the higher the pressure, the lower the sensitivity is continuously reduced.

As described above, it is important to arrange the semiconductor strain gauge as close to the fixed end of the diaphragm as possible for high accuracy. Next, FIGS. 10 and 11 show embodiments in which these measures are taken. These drawings are plan views of the SOI substrate of the detection unit as viewed from the second silicon substrate 3 side. The square 26 shown by the dotted line in FIG.
FIG. 3 shows a substantial size of the diaphragm 16 formed on the first silicon substrate 1 on the back surface of the thermal oxide film 2. The shape of the groove 15 that separates the outer frame portion 22 from the silicon pad 19 and the like partially protrudes outside the square portion 26. That is, the outer frame portion 22 around the semiconductor strain gauge 20a in the radial direction is processed by etching to form the concave portion 27. It is possible to partially dispose the lead lead-out portion 23 in the concave portion 27, and dispose the semiconductor strain gauge 20a in the radial direction closer to the outer periphery of the square portion 26, in other words, closer to the fixed end of the diaphragm 16. be able to. In the case of this figure, the semiconductor strain gauge 2 in the tangential direction is used.
Placing Ob near the fixed end of diaphragm 16 is easier than radial semiconductor strain gauge 20a.

FIG. 11 shows another method of arranging the semiconductor strain gauges. The longitudinal direction of all the semiconductor strain gauges is made to coincide with the longitudinal direction of the groove 28 formed between the silicon pads 19. As shown in the figure, the groove 28 is designed to be wide and a part of the lead lead-out portion 23 is routed into the groove 28 so that the semiconductor strain gauge 20a in the radial direction becomes closer to the square portion 26 shown by the dotted line. It becomes possible to arrange.

Next, another embodiment for continuously and accurately detecting the pressure from the low pressure region to the high pressure region is shown in FIGS.
This will be described below. The stopper is not brought into contact with the pedestal in the entire area of the pressure measurement, and the stopper is brought into contact with the pedestal only when the maximum pressure to be detected is exceeded. By doing so, the pressure resistance of the diaphragm itself can be ensured even if a pressure higher than the rated pressure is applied. In addition, by reducing the thickness of the diaphragm while maintaining the withstand voltage, the sensitivity of a signal generated in the bridge circuit to pressure can be increased. If you simply amplify the signal in this case,
The output characteristics are as shown in FIG. Generally, when the diaphragm is thinned to near the breaking limit of the diaphragm, the linearity of the output voltage with respect to the pressure is deteriorated as shown in the output characteristic (g). If a microcomputer or the like in a system that uses the semiconductor pressure sensor quantitatively recognizes the magnitude of the nonlinearity in advance, there is no problem in use. It is also possible to correct this non-linearity by a signal processing circuit in the semiconductor pressure sensor and (h) output it as linearized as in the output characteristic. FIG. 13 shows a schematic block diagram of this linearization. The adjustment circuit 30 adjusts the offset and sensitivity of the signal generated in the bridge circuit 29 composed of a semiconductor strain gauge. The signal after the adjustment is amplified by the amplifier circuit 31 to a desired voltage value. Finally, the nonlinearity of the signal of the amplifier circuit 31 is corrected by the linearization circuit 32. Note that a detailed description of each circuit is not an essential problem and will be omitted.

On the other hand, it is not always easy to fabricate the detector so that the stopper 18 contacts the pedestal 4 at a predetermined pressure (for example, just 1 Mpa and the width of variation is small). This is because the design value of the gap 21 between the stopper 18 and the pedestal 4 is as narrow as about 1 micron,
This is because the size of the gap 21 is affected by the dimensional variation during the etching process of the detection unit made of the OI substrate and the deformation due to the thermal stress after joining to the pedestal 4. Therefore, as shown in FIG. 14, after the diaphragm 16 is processed to be slightly thicker in advance and joined to the pedestal 4, a pressure is applied to the detecting portion once to measure a pressure value at which the stopper 18 and the pedestal 4 come into contact. . In order to bring the stopper 18 into contact with the pedestal 4 with a pressure of exactly 1 Mpa, how much should the first silicon substrate 1 be etched and the thickness of the diaphragm 16 adjusted? Predict exactly. Based on the predicted result, the first silicon substrate 1
The diaphragm 16 is further processed to a predicted value by etching using the thermal oxide film 34 formed on the surface of the first silicon substrate 1 as a mask in a state where the base 16 and the pedestal 4 are joined. Further, a portion to be removed by etching is indicated by 33 in the figure.

The pressure from the low pressure region to the high pressure region can be detected with high accuracy even if the stopper 18 does not come into contact with the pedestal 4 at a predetermined pressure (for example, just 1 Mpa and the variation width is small). FIG. 15 shows a method of the signal processing circuit to be used. This drawing shows that the stopper 18 is
This is a case where the pressure in contact with is varied from 1.0 Mpa to 1.5 Mpa in the region B. After appropriately adjusting the offset of the signal generated in the bridge circuit, the smaller one of the amplification factors of the signal was set as the output characteristic (S1), and the larger one was set as the output characteristic (S2). Two output characteristics (S1) and (S
2) The pressure at which the stopper 18 comes into contact with the pedestal 4, that is, the pressure at which the step breaks is 1.25 Mp, which is the median value of the area B.
2 shows an example of a. From the output characteristics (S1) in the low-pressure region of the region A, to the output characteristics (S2) in the high-pressure region of the region C.
The value of the pressure to be detected is recognized from. Then, in the intermediate region B, the pressure value is recognized from the output characteristics (S1) or (S2). In the example of this figure, the pressure value is recognized from the output characteristic (S1) at a pressure of 1.25 Mpa or less, and from the output characteristic (S2) at a pressure of 1.25 Mpa or more. The output voltage Vo of both output characteristic signals is determined by using a microcomputer in a system using the semiconductor pressure sensor, which output characteristic signal should be estimated in the region B.
Can be easily calculated and processed.

The embodiments described so far are all examples in which the thickness of the diaphragm is uniform. By partially changing the thickness of the diaphragm, it is possible to freely set the ratio of the sensitivity of the signal generated in the bridge circuit consisting of the semiconductor strain gauge to the pressure in the low-voltage region and the high-pressure region. improves. This embodiment is shown in FIG. As shown, the diaphragm is thinner 16a.
The semiconductor strain gauge is formed on the back surface of each of the thin and thick portions of the diaphragm. FIGS. 17 and 18 show plan views of the first silicon substrate 1 as viewed from the diaphragm side. FIG. 17 shows two radial semiconductor strain gauges 20a and 20c on the back surface of the thin diaphragm 16a, and two tangential semiconductor strain gauges 20b and 20d on the thick diaphragm 1.
This is an embodiment in which a boss 17 is formed on the thin portion 16a of the diaphragm, which is formed on the back surface of the portion 6b. In this embodiment, the thin portion 16a has a square shape. on the other hand,
FIG. 18 shows an embodiment in which both the thin portion diaphragm 16a and the thick portion diaphragm 16b are triangular, and the boss 17 is formed on the thin portion 16a of the diaphragm.
One thin semiconductor strain gauge in the radial direction and one semiconductor strain gauge in the tangential direction are formed on each of the thin portion and the thick portion of the diaphragm.

It is needless to say that the detecting section is not necessarily limited to the detecting section having the SOI structure, but can be applied to the semiconductor pressure sensor having the non-SOI structure shown in FIG. The back surface of the silicon substrate 100 is etched to form a projection 103 and a diaphragm 104 which also serve as a boss and a stopper.
Is formed. A semiconductor strain gauge 105 is formed on the surface of the silicon substrate 100 by a method such as diffusion or ion implantation, and the surface is covered with a protective film 106 such as a thermal oxide film. When the silicon substrate 100 is bonded to a pedestal 101 made of a glass substrate or the like by anodic bonding or the like, a gap 102 is formed between the projection 103 and the pedestal 101. In this embodiment, as in the case of the detection unit having the SOI structure, it is needless to say that only one set of bridge circuits is formed in the diaphragm 104.

[0025]

According to the present invention, it is possible to provide a semiconductor pressure sensor having excellent pressure resistance and capable of measuring pressure from a low pressure region to a high pressure region with high accuracy. In addition, since the pressure detecting unit and the signal processing circuit have a simple configuration and can be reduced in size, a low-cost semiconductor pressure sensor with excellent productivity can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration diagram of a semiconductor pressure sensor according to the present invention.

FIG. 2 is a diagram showing one embodiment of a detailed cross-sectional structure of a detection unit of the semiconductor pressure sensor according to the present invention.

FIG. 3 is a diagram showing one embodiment of a plan view of a second silicon substrate of the semiconductor pressure sensor according to the present invention.

FIG. 4 is a diagram showing one embodiment of a plan view of a first silicon substrate of the semiconductor pressure sensor according to the present invention.

FIG. 5 is a diagram showing an output characteristic example of the semiconductor pressure sensor according to the present invention.

FIG. 6 is a diagram showing a relationship between a position of a semiconductor strain gauge and detection sensitivity in a high-pressure region.

FIG. 7 is a diagram showing another embodiment of the output characteristics of the semiconductor pressure sensor according to the present invention.

FIG. 8 is a view showing another embodiment of the sectional structure of the detecting section of the semiconductor pressure sensor according to the present invention.

FIG. 9 is a diagram showing another embodiment of the sectional structure of the detecting section of the semiconductor pressure sensor according to the present invention.

FIG. 10 is a plan view showing another embodiment of the second silicon substrate of the semiconductor pressure sensor according to the present invention.

FIG. 11 is a plan view showing another embodiment of the second silicon substrate of the semiconductor pressure sensor according to the present invention.

FIG. 12 is a diagram showing another output characteristic example of the semiconductor pressure sensor according to the present invention.

FIG. 13 is a diagram showing a schematic block diagram of a method for linearizing output characteristics.

FIG. 14 is a view showing a manufacturing method for accurately determining the pressure at which the stopper and the base come into contact with each other.

FIG. 15 is a diagram showing another embodiment of the output characteristics of the semiconductor pressure sensor according to the present invention.

FIG. 16 is a view showing another embodiment of the cross-sectional structure of the detection unit of the semiconductor pressure sensor according to the present invention.

FIG. 17 is a plan view showing another embodiment of the first silicon substrate of the semiconductor pressure sensor according to the present invention.

FIG. 18 is a plan view showing another embodiment of the first silicon substrate of the semiconductor pressure sensor according to the present invention.

FIG. 19 is a diagram showing a cross-sectional structure of a detection unit having a non-SOI structure of the semiconductor pressure sensor according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st silicon substrate, 2,106 ... thermal oxide film, 3 ...
Second silicon substrate, 4,101 base, 5 low melting point glass, 6 stem, 7 housing, 8 signal processing circuit, 9 solder, 10 through hole, 11 lead pin, 12 high melting point Glass member, 13: conductive wire, 14: metal thin film, 15, 28: groove, 16, 104: diaphragm, 16a: thin diaphragm portion, 16b: thick diaphragm portion, 17: boss, 18: stopper, 19: silicon pad, 20: semiconductor strain gauge, 2
0a: radial semiconductor strain gauge, 20b: tangential semiconductor strain gauge, 20c: radial semiconductor strain gauge,
20d: semiconductor strain gauge in the tangential direction, 21, 102: gap, 22: outer frame portion, 23: lead extraction portion, 2
4, 25: inclined portion, 26: square portion indicating diaphragm size, 27: concave portion, 29: bridge circuit, 30: adjusting circuit, 31: amplifying circuit, 32: linearizing circuit, 33: removed portion, 34 ... thermal oxide film, 100 ... silicon substrate, 103 ... protrusion, 105 ... semiconductor strain gauge.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Miya ▲ saki ▼ Atsushi 2520 Oji Takaba, Hitachinaka City, Ibaraki Prefecture Inside the Automotive Equipment Division, Hitachi, Ltd. (72) Inventor Masayuki Miki 2520 Oaza Takaba, Hitachinaka City, Ibaraki Prefecture Address Co., Ltd.Hitachi, Ltd.Automotive Equipment Division (72) Inventor Masanori Kubota 2477 Takaba, Hitachinaka-shi, Ibaraki Pref.Hitachi Car Engineering Co., Ltd. (72) Inventor Makoto Yamaguchi 2477 Takaba, Hitachinaka-shi, Ibaraki Prefecture Incorporated Hitachi Car Engineering Co., Ltd. (72) Inventor Hisao Sonobe 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture (72) Inventor Shimada, Hitachi, Ltd. Satoshi 7-1-1, Omikamachi, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Masahiro Matsumoto 7-1-1, Omikamachi, Hitachi City, Ibaraki Prefecture, Hitachi Research Laboratory, Hitachi, Ltd.

Claims (18)

[Claims] 1. A silicon chip having a boss, a stopper, a semiconductor strain gauge, and a diaphragm having a bridge circuit formed on the surface thereof, a pedestal joined to the silicon chip, and the diaphragm deformed in response to an applied pressure. ,
The stopper is brought into contact with the pedestal at a predetermined pressure, so that a pressure in a low-pressure area before the stopper comes into contact with the pedestal and a pressure in a high-pressure area after the stopper comes into contact with the pedestal can be respectively detected. And a signal processing circuit. 2. The semiconductor pressure sensor according to claim 1, wherein the boss and the stopper are the same element. 3. The silicon chip according to claim 1, wherein the silicon chip is SO
A semiconductor pressure sensor comprising an I-substrate, wherein a boss is arranged on one surface of a diaphragm, and a stopper and a bridge circuit are arranged on the other surface. 4. The semiconductor pressure sensor according to claim 1, wherein the pedestal is formed of a glass substrate and is bonded to the silicon chip by anodic bonding. 5. The semiconductor pressure sensor according to claim 4, wherein the semiconductor strain gauge is disposed at least 90% or more outside the diameter of the diaphragm on the fixed end side. 6. The semiconductor pressure sensor according to claim 3, wherein the width of the stopper is smaller than the width of the boss. 7. The semiconductor pressure sensor according to claim 1, wherein the signal processing circuit has a function of individually outputting an output signal in a low voltage region and an output signal in a high voltage region. 8. A silicon chip having a diaphragm having a bridge circuit formed of a stopper and a semiconductor strain gauge formed on a surface thereof is joined to a pedestal, and the diaphragm is deformed in response to an applied pressure, and the stopper is deformed at a predetermined pressure. So that the pressure in the low-pressure area before the stopper contacts the pedestal and the pressure in the high-pressure area after the stopper contacts the pedestal can be detected with high accuracy. 1. A semiconductor pressure sensor comprising a signal processing circuit according to claim 1. 9. A silicon chip having a diaphragm on the surface of which a bridge circuit comprising a stopper having a non-uniform height and a semiconductor strain gauge is joined to a pedestal, and the stopper is attached to the pedestal at the lowest pressure of the fluid to be measured. A semiconductor pressure sensor characterized in that it can be continuously and non-linearly detected from a pressure in a low pressure region to a pressure in a high pressure region by being manufactured so as to be in contact with the semiconductor pressure sensor. 10. The SOI substrate according to claim 3, wherein the SOI substrate is composed of a laminate of a first silicon substrate, a thermal oxide film, and a second silicon substrate, and a diaphragm and a boss are formed on the first silicon substrate. A stopper, a bridge circuit including a semiconductor strain gauge, a lead lead portion, a pad portion, and an outer frame portion were processed on the silicon substrate, and a pedestal was processed on the second silicon substrate so that the bridge circuit was hermetically sealed. A semiconductor pressure sensor which is joined to an outer frame portion and a pad portion, and electrically connects the bridge circuit and an external signal processing circuit via a conductive member in a through hole provided in the pedestal. 11. The semiconductor strain gauge according to claim 10, wherein a part of an inner dimension of the outer frame portion processed on the second silicon substrate is made larger than an outer peripheral dimension of the diaphragm processed on the first silicon substrate. A semiconductor pressure sensor characterized in that it can be disposed as much as possible on a fixed end of a diaphragm. 12. A semiconductor memory device according to claim 10, wherein the semiconductor silicon strain gauge is arranged as parallel as possible to said groove by separating the semiconductor strain gauge into four grooves formed on the second silicon substrate. A semiconductor pressure sensor characterized in that it can be arranged at a fixed end of a semiconductor pressure sensor. 13. A silicon chip having a diaphragm having a bridge circuit formed of a stopper and a semiconductor strain gauge formed on the surface thereof is joined to a pedestal, and the diaphragm is deformed in accordance with an applied pressure to measure a fluid to be measured. A semiconductor pressure sensor having a signal processing circuit for amplifying and linearizing a signal of a bridge circuit, wherein the stopper is brought into contact with the pedestal only when the pressure exceeds a power upper limit. 14. A method according to claim 1, wherein after the pressure is applied once to measure the pressure value at which the stopper comes into contact with the pedestal, the diaphragm is further etched to make the thickness of the diaphragm an appropriate predetermined dimension. A semiconductor pressure sensor comprising: 15. The semiconductor according to claim 1, wherein the thickness of the diaphragm is not uniform, and there are a thin portion and a thick portion, and semiconductor strain gauges are disposed on the surfaces of the thin portion and the thick portion, respectively. Pressure sensor. 16. The semiconductor pressure sensor according to claim 15, wherein the stopper is formed on the surface of the thin portion of the diaphragm. 17. The semiconductor pressure sensor according to claim 1, wherein an output signal with respect to the pressure has a step-break characteristic between a low pressure region and a high pressure region. 18. The method according to claim 1, wherein the smaller the amplification factor of the signal generated in the bridge circuit portion, the lower the output signal of the low voltage region,
A semiconductor pressure sensor, which is a signal processing circuit that uses a larger one as an output signal in a high voltage range.