JP2985462B2 - Semiconductor pressure gauge - 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 gauge having improved linearity characteristics.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view of the structure of a conventional example generally used in the prior art.
No. in the official gazette. In the figure, reference numeral 1 denotes a semiconductor chip. In this case, silicon is used. Reference numeral 2 denotes a concave portion provided on the semiconductor chip 1 and constituting a diaphragm 3 serving as a strain-flexing portion in the semiconductor chip 1.

[0003] Reference numeral 4 denotes a semiconductor pressure detecting element provided in the strain generating portion 3 of the semiconductor chip 1. In this case, a piezoresistive element is used. Reference numeral 5 denotes a glass support substrate made of Pyrex glass, one surface of which is connected to one surface of the semiconductor chip and which constitutes the recess and the pressure introducing chamber 6. In this case, they are joined by anodic joining or the like. Reference numeral 7 denotes a communication hole provided in the glass support substrate and communicating with the pressure introduction chamber 6.
8 is a pressure vessel. The other surface of the glass support substrate 5 is joined.

[0004] In the above configuration, introduces low-pressure side pressure P _L in the pressure introduction chamber 6, the high side pressure P _H is applied from the outside of the diaphragm 3, the diaphragm 3, the high side pressure P _H - low side pressure P Displaced by _L differential pressure. If this displacement is electrically detected by a semiconductor pressure detecting element, an electric signal output corresponding to the differential pressure can be obtained.

[0005]

However, in such a device, the output ∝Σπ _i σ ⁱ (where Σ is i =
An operation symbol of the addition and sum from 0 to i = ∞, π indicates a piezoresistance coefficient, and σ indicates a stress element. Here, when σ is small, that is, when the differential pressure is low, the quadratic term of σ and below can be ignored, and the linearity is good. However, when σ is large, that is, when the differential pressure is high, the second and lower terms of σ cannot be ignored, and the linearity deteriorates.

The present invention solves this problem. An object of the present invention is to provide a semiconductor pressure gauge with improved linearity characteristics.

[0007]

In order to achieve this object, the present invention provides a semiconductor pressure sensor having a semiconductor chip and a concave portion provided on the semiconductor chip and forming a diaphragm which is a strain generating portion on the semiconductor chip. A semiconductor pressure gauge provided with a semiconductor pressure detecting element provided on the semiconductor chip outside the diaphragm of the semiconductor chip.

[0008]

In the above construction, when the low pressure side pressure is introduced into the pressure introducing chamber and the high pressure side pressure is applied from the outside of the diaphragm, the diaphragm is displaced by the pressure difference between the high pressure side pressure and the low pressure side pressure. If this displacement is electrically detected by a semiconductor pressure detecting element, an electric signal output corresponding to the differential pressure can be obtained. Hereinafter, a detailed description will be given based on embodiments.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
FIG. 2 is a side view of FIG. In the figure, the configuration of the same symbol as FIG. 5 represents the same function. Hereinafter, only differences from FIG. 5 will be described. Reference numeral 11 denotes a semiconductor pressure detecting element provided on the semiconductor chip outside the diaphragm of the semiconductor chip. The distance r ₁ from the center of the gauge is r ₁ / r ≒ 1.
5 (r: half the length of the side of the diaphragm).

In this example, the semiconductor pressure detecting element 11 is a shear type semiconductor pressure detecting element. Conventionally, a semiconductor pressure detecting element is formed at an appropriate position in the diaphragm 3 (for example, r = r _2, σ _x + σ _y ≒ −20 kg).
/ mm ² ), in the present proposal, | σ _x outside the diaphragm 11
+ Σ _y | ≦ 15 kg / mm ² (for example, r = r _1, σ _x + σ _y = −8 kg / mm ² ).

[0011] In the above configuration, introduces low-pressure side pressure P _L in the pressure introduction chamber 6, the high side pressure P _H is applied from the outside of the diaphragm _3, the diaphragm 3, the high side pressure P _H
- displaced by the differential pressure of the low-pressure side pressure P _L. If this displacement is electrically detected by the semiconductor pressure detecting element 4, an electric signal output corresponding to the differential pressure can be obtained. For shear gauges,
V _0UT = KπτV _S (K: constant, π: piezoresistance coefficient,
τ: shear stress, V _S : drive voltage).

FIG. 3 shows the relationship between the position r of the semiconductor pressure detecting element 4 and the stress σ. As shown in FIG. 4, the linearity L of the electric output V _0UT with respect to the input pressure was found to be substantially proportional to the stress σ _x + σ _y at the position of the semiconductor pressure detecting element 4 from experiments. When σ is large, that is, when the differential pressure is high, the second and lower terms of σ cannot be ignored and the linearity deteriorates.

Therefore, it has been found that it is necessary to make | σ _x + σ _y | ≦ 15 kg / mm ^{2 in} order to make the linearity L within ± 0.5%. In a semiconductor pressure gauge, the semiconductor pressure detecting element 11 is usually arranged on the diaphragm 3.
However, when measuring a high pressure of about 100 kg / mm ² or more, as shown in FIG. 3, on the diaphragm, as in the case of r = r ₁ , approximately | σ _x + σ _y | ≦ 15 kg / mm ² It is difficult to get. By placing outside diaphragm 3 |
σ _x + σ _y | ≦ about 15 kg / mm ² , and the linearity L is set to ± 0.
It can be within 5%.

As a result, (1) The linearity of the output itself of the semiconductor pressure detecting element 11 with respect to pressure can be reduced with a simple configuration without using external means such as correction using an electric circuit in the high pressure measurement range. Can be better. (2) A high-precision semiconductor pressure gauge with good linearity can be manufactured at low cost.

In the above embodiment, the rectangular diaphragm 3 has been described. However, the present invention is not limited to this, and a circular diaphragm may be used. In short, any diaphragm may be used. Further, a so-called integrated semiconductor pressure gauge in which a signal processing circuit is formed on the semiconductor chip 1 may be used. Further, it has been described that the shear-type semiconductor pressure detecting element 11 is used. However, a plurality of piezoresistive elements may be formed on the semiconductor chip 1 or a bridge using four pieces may be used.

[0016]

As described above, the present invention relates to a semiconductor pressure gauge including a semiconductor chip and a concave portion provided on the semiconductor chip and constituting a diaphragm which is a strain-causing portion in the semiconductor chip. And a semiconductor pressure gauge provided on the semiconductor chip outside the diaphragm.

As a result, (1) the linearity of the output of the semiconductor pressure detecting element itself with respect to pressure is improved in a simple configuration without using external means such as correction using an electric circuit in the high pressure measurement range. You can do it. (2) A high-precision semiconductor pressure gauge with good linearity can be manufactured at low cost. Therefore, according to the present invention, a semiconductor pressure gauge having improved linearity characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is an operation explanatory diagram of FIG. 1;

FIG. 4 is an operation explanatory diagram of FIG. 1;

FIG. 5 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip 2 ... Concave part 3 ... Diaphragm 4 ... Semiconductor pressure detecting element 5 ... Substrate 6 ... Pressure introduction chamber 11 ... Semiconductor pressure detecting element

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01L 9/04-9/06 H01L 29/84

Claims (1)

(57) [Claims] 1. A semiconductor pressure gauge comprising: a semiconductor chip; and a concave portion provided on the semiconductor chip and constituting a diaphragm serving as a strain-causing portion on the semiconductor chip, wherein the semiconductor pressure gauge is provided on the semiconductor chip outside the diaphragm of the semiconductor chip. A semiconductor pressure gauge, comprising: a semiconductor pressure detecting element.