JPH0797058B2 - Semiconductor pressure transducer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor pressure transducer using a multi-function differential pressure sensor, and particularly for obtaining a temperature-compensated differential pressure signal with less static pressure influence. It relates to a suitable semiconductor pressure transducer.

[Prior Art] Conventionally, various differential pressure sensors for detecting a differential pressure and a temperature have been proposed, but FIG. 8 shows the principle of the differential pressure sensor described in JP-A-56-87196. It is an example of a structure. The differential pressure sensor is composed of a pressure receiving portion 1 and a differential pressure detecting portion 2, and <110> is provided substantially at the center of the differential pressure detecting portion 2.
A measuring diaphragm 3 made of plane n-type single crystal silicon is provided. The measuring diaphragm 3 is a concave diaphragm, and is provided with a central rigid body portion 5 in the central portion and a thick outer peripheral fixing portion 6 in the outer peripheral portion, and a thin wall connecting the central rigid body portion 5 and the outer peripheral fixing portion 6. An annular strain generating section 8 is provided.
A gauge resistance sensitive to the differential pressure is formed in the annular strain generating portion 8. Further, the outer peripheral fixing portion 6 is formed with a gauge resistance sensitive only to the temperature. These gauge resistors are made insensitive to high static pressure, and are connected to external circuits via pressure-resistant airtight terminals 10 provided on the main body 9 and lead wires 11, respectively. The measuring diaphragm 3 is a fixed base made of an insulating material such as glass having a Young's modulus different from that of silicon.
The fixing table 12 is adhered to a support member 13 made of a metal tube and fixed to the main body 9.

The operation of the differential pressure sensor will be briefly described with reference to FIG.
When the high-pressure fluid is introduced from the high-pressure fluid inlet 16 of the high-pressure side flange 15, the pressure P _H of the high-pressure fluid is passed through the high-pressure side seal diaphragm 18, the pressure guiding path 19, the high pressure side isolation chamber 20, and the pressure guiding path 21. It acts on one side of the measuring diaphragm 3. Similarly, when the low-pressure fluid is also introduced from the low-pressure fluid introduction port 23 of the low-pressure side flange 22, the pressure P _L of the low-pressure fluid is changed to the low-pressure side seal diaphragm 25, the pressure guiding path 26, the low pressure side isolation chamber 28, and the pressure guiding path 29. Acts on the other side of the measuring diaphragm 3 via. As a result,
The ring-shaped strain portion 8 of the measurement diaphragm 3 bends in accordance with the pressure difference, which changes the gauge resistance value. Then, a signal proportional to the differential pressure is obtained from the gauge resistance of the annular strain generating portion 8 and a signal proportional to the temperature is obtained from the gauge resistance of the outer peripheral fixing portion 6. A pressure signal can be obtained.

[Problems to be Solved by the Invention]

However, since the static pressure applied to both sides of the measurement diaphragm 3 of the differential pressure sensor is usually as high as 100 atmospheric pressure or more, the measurement diaphragm 3 is deformed due to irregular contraction of the enclosed liquid in the chambers on both sides or deformation of the main body 9, Along with that, the resistance value of the gauge resistance changes. Therefore, the signal due to the static pressure is superimposed on the signal due to the differential pressure, and an accurate differential pressure signal cannot be output. That is, the static pressure influences the result, resulting in an error. In order to prevent this static pressure error, the liquid volumes of the enclosed liquids in the chambers on both sides must be exactly the same, and the main body 9 must have large rigidity so as not to be deformed by static pressure. This has been a major limitation, and has been an obstacle to downsizing and cost reduction of the differential pressure sensor.

In order to solve this, a semiconductor pressure converter as described in Japanese Patent Laid-Open No. 58-120142 has been proposed.
This semiconductor pressure transducer has a small strain generated by a differential pressure, and a static pressure sensing gauge is formed on the outer peripheral fixed portion 6 where a large static pressure causes a strain due to the Young's modulus difference from the fixed base 12.
It is designed to correct the effects of static pressure. However, in the case of this semiconductor pressure transducer, if the sensitivity of the static pressure sensor is to be increased, the thickness of the measurement diaphragm 3 is reduced so that the yak ratio between the fixed base 12 and the measurement diaphragm 3 when static pressure is applied. It is necessary to increase the stress based on the difference, which causes a problem that crosstalk due to the static pressure of the differential pressure sensor increases.

It is an object of the present invention to provide a semiconductor pressure converter capable of obtaining a differential pressure signal having a small influence of static pressure.

[Means for Solving the Problems]

In order to achieve such an object, the present invention provides a central rigid body portion in the central portion, a thick outer peripheral fixing portion in the outer peripheral portion, and a thin annular strain generating portion connecting the central rigid body portion and the outer peripheral fixing portion. In a semiconductor pressure transducer provided with a measuring diaphragm made of silicon and a fixing base that fixes the measuring diaphragm and has a Young's modulus different from that of silicon, a differential pressure detecting element is provided in the annular strain generating section, and the central rigid body section is provided. Is provided with at least one static pressure detecting element.

[Action]

According to the above-mentioned configuration, the static pressure detecting element is formed in the central rigid body portion, and even if the position of this static pressure detecting element is deviated by some factor, the stress of the central rigid body portion is irrespective of the radial position. Since it is constant, a stable static pressure output can be obtained. Therefore, a differential pressure signal with little influence of static pressure can be obtained.

〔Example〕

 Hereinafter, the present invention will be described based on embodiments shown in the drawings.

1 to 3 relate to the first embodiment of the present invention, and the same or equivalent parts as those shown in FIG. 8 are designated by the same reference numerals.

In the annular strain generating portion 8 of the measuring diaphragm 3, a P-type gauge resistor 31 which is a differential pressure detecting element sensitive to a differential pressure has a maximum sensitivity. Method or the ion implantation method. Two gauge resistors 31 are formed in the vicinity of the central rigid body portion 5 and two in the vicinity of the outer peripheral fixed portion 6 in order to reduce the influence of temperature, and these resistors are assembled in a Wheatstone bridge to output differentially. I'm supposed to get it. Further, two P-type gauge resistors 32, which are static pressure detecting elements, are also formed on the outer peripheral fixing portion 6 along the tangential direction of the <111> axis direction by a diffusion method or an ion implantation method.
Further, at least one P-type gauge resistor 33, which is a static pressure detecting element, is provided in the central rigid body portion 5 along the radial direction of the <110> axis direction.
One, for example two, are formed facing each other in the vicinity of the outer peripheral surface by a diffusion method or an ion implantation method. These gauge resistors 32 and 33 are assembled in a Wheatstone bridge to obtain outputs differentially.

Next, the operation of the first embodiment of the present invention will be described.

Fig. 3 shows outer diameter 14 mm, inner diameter 10 mm, annular strain element 8 thickness 0.09 mm, central rigid body 5 outer diameter 7 mm, thickness 0.5 mm.
The measurement diaphragm 3 and the fixing base 12 (made of Pyrex glass) 12 having an outer diameter of 14 mm and a thickness of 3.8 mm are bonded to a metal pipe supporting member 13 having a diameter of 7 mm, and the whole is 15 MPa (≈15
Measurement diaphragm 3 when static pressure of 0 kgf / cm ² ) is applied
The generated stress on the surface is shown. In the figure, σ
θ represents tangential stress, and σ _z represents depth stress.

Since stress is hardly generated in the central rigid body portion 5 and the outer peripheral fixing portion 6 when a differential pressure is applied, the gauge resistors 33 and 32 are not sensitive to the differential pressure and are based on the difference in Young's modulus between the silicon and the fixing base 12. It is mainly sensitive to strain due to static pressure. Further, since the stress of the central rigid body portion 5 is constant regardless of the position in the radial direction, a stable static pressure output can be obtained even if the position of the gauge resistor 33 deviates due to some factor. Gauge resistors 33 and 32 are installed on both the central rigid body portion 5 where the stress is maximized by static pressure and the outer peripheral fixed portion 6 where reverse stress is generated, which increases the sensitivity of the static pressure sensor. It is possible to obtain an output 1.5 to 2 times as high as that of the conventional static pressure sensor constituted only by the gauge resistance on the outer peripheral fixing portion 6.

FIG. 4 and FIG. 5 relate to the second embodiment of the present invention.
The difference from the embodiment is that the static pressure detecting element is the central rigid body portion 5.
The point is that it is only installed. 2 which is a static pressure detection element
The gauge resistance 33 is formed in the <110 axis direction> with the highest sensitivity, and the other two gauge resistances 33 are formed in the <100> axis direction with the lowest sensitivity.
3 is built in the Wheatstone Bridge. According to the present embodiment, the sensitivity of the static pressure sensor is about half that of the first embodiment, but the stress due to the static pressure of the central rigid body portion 5 is the first.
Since it is constant regardless of the position as in the embodiment, a constant and stable output can be obtained even if the position of the gauge resistor 33 deviates due to some cause.

FIG. 6 and FIG. 7 relate to the third embodiment of the present invention,
The difference from the example is that the gauge resistance in the <100> axis direction is 3
3 is an n-type. For example, a P well is formed and an n-type gauge resistor is formed in it. Since the n-type gauge resistance has the highest sensitivity in the <100> axis direction,
Compared with the second embodiment, the auxiliary strain sensor can obtain an output more than double.

〔The invention's effect〕

As described above, according to the present invention, the static pressure detecting element having high sensitivity and stable output can be formed on the same chip, so that a differential pressure signal with less static pressure influence can be obtained.

[Brief description of drawings]

1 to 3 relate to a first embodiment of the present invention, FIG. 1 is a perspective view showing a measurement diaphragm cut away at the center, FIG. 2 is a plan view of the measurement diaphragm, and FIG. A distribution diagram of stress generated in the diaphragm, FIGS. 4 and 5 relate to a second embodiment of the present invention, FIG. 4 is a longitudinal sectional view of the measurement diaphragm, FIG. 5 is a plan view of the measurement diaphragm, and FIG. FIG. 7 and FIG. 7 relate to a third embodiment of the present invention,
FIG. 6 is a vertical sectional view of the measuring diaphragm, FIG. 7 is a plan view of the measuring diaphragm, and FIG. 8 is a vertical sectional view showing the principle structure of the differential pressure sensor. 3 ... Measuring diaphragm, 5 ... Central rigid body part, 6 ... Peripheral fixed part, 8 ... Annular strain part, 12 ... Fixing base, 31 ... Gauge resistance which is a differential pressure detecting element, 32, 33 ... … A gauge resistance that is a static pressure detection element.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-87196 (JP, A) JP-A-56-40735 (JP, A) JP-A-58-120142 (JP, A) JP-A-58- 167432 (JP, A)

Claims (1)

[Claims] 1. A silicon body having a central rigid body portion in the central portion thereof, a thick outer peripheral fixing portion in the outer peripheral portion thereof, and a thin annular strain portion connecting the central rigid body portion and the outer peripheral fixing portion. In a semiconductor pressure transducer comprising: a measuring diaphragm and a fixing base that fixes the measuring diaphragm and has a Young's modulus different from that of silicon, at least one differential pressure detecting element is provided in the annular strain section and at least one in the central rigid body section. 2. A semiconductor pressure converter, characterized in that each of the static pressure detecting elements is provided.