JP2748074B2 - Resistance type pressure sensor element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance type pressure sensor element for converting a change in pressure into a change in resistance.

[0002]

2. Description of the Related Art FIG. 3 is a plan view showing the structure of a conventional resistance type pressure sensor element. In the figure, 1 is (10
The silicon substrate 2 of the 0) plane has a diaphragm portion 31 ₁ , 3 ₂ , 3, formed in a thin film on the surface of the silicon substrate 1.
3 ₃ and 3 ₄ are resistors formed on the surface edge of the diaphragm portion 2. These resistors 3 ₁ , 3 ₂ , 3 ₃ and 3 _{4 are provided.}
Is 90 degrees alternately with respect to the edge of the diaphragm part 2.
It is formed and arranged with a shift every time. Reference numeral 4 denotes a wiring pattern for electrically connecting the resistors 3 ₁ , 3 ₂ , 3 ₃ , and 3 ₄ , respectively, 5 ₁ and 5 ₂ represent input terminals, 5 ₃ and 5 ₄ represent output terminals. These resistors 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ have resistance values R ₁ , R ₂ , R ₃ , R _{4 respectively} , and are wired so as to form a bridge circuit as shown in FIG. ing.

In such a configuration, when pressure is applied to the diaphragm portion 2, each of the resistors 3 ₁ , 3 ₂ , 3 ₃ , 3 _{4 is formed.}
The same stress (strain) is generated at the position. In addition, since the directions of the resistors 3 ₁ , 3 ₂ , 3 ₃ , and 3 ₄ with respect to the edge of the diaphragm portion 2 are alternately shifted by 90 degrees, the resistance value determined from the piezo coefficient of the resistance and the stress (strain). Is that when the resistances R ₁ and R ₃ increase, the resistances R ₂ and R ₄ decrease (and vice versa). Further, the resistance type pressure sensor element configured as described above can be used even when stress (strain) is generated in the diaphragm 2 due to a temperature change or the like.
Equal stresses (strains) are generated at the positions of the resistors 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ , and the same output as when pressure is applied is generated.

[0004]

The conventional resistance type pressure sensor element having the above-described structure has two cases: a case where a pressure to be measured is applied to the diaphragm 2; and a case where a temperature change which causes an error occurs. In this case, the same phenomenon occurred, and an output was generated by this. Therefore, there was a problem that the detected output obtained in response to the change in pressure had a poor S / N ratio.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to reduce only the pressure applied to the diaphragm without increasing the S / N ratio without being affected by temperature changes. It is another object of the present invention to provide a resistance type pressure sensor element which can be detected by a pressure sensor.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a substrate portion having at least one of a through hole and a depression in one surface, and a substrate portion having one or more recesses. The formed diaphragm portion, a first resistor and a second resistor formed opposite to each other near the edge of the surface of the diaphragm portion, and the first resistor and the second resistor near the edge of the rear surface of the diaphragm portion. The third resistor and the fourth resistor formed opposite to each other at a position rotated by about 90 degrees with respect to the position of the second resistor, and the first resistor, the second resistor, and the third resistor. And a wiring pattern for bridge-connecting the fourth resistor and the fourth resistor.

[0007]

According to the present invention, when pressure is applied, compression and tensile stress having substantially the same size are generated alternately at the position where each resistor is formed. When the temperature changes, the compression having substantially the same size is formed at each resistor formation position. Or a unified tensile stress occurs.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view showing the configuration of an embodiment of the resistance type pressure sensor element according to the present invention. FIG. 2 is a partially cutaway perspective view of FIG. is there. In the figure, a through hole 1a having a substantially trapezoidal cross section is formed in the center of a silicon substrate 1A.
On the surface of the silicon substrate 1A, a rectangular diaphragm film 2A made of a laminated film of a plurality of Si ₃ N ₄ films is formed so as to cover the opening of the through-hole 1a to form a diaphragm portion. 1b is a thick portion of the silicon substrate 1.

Moreover, this is the surface side of the diaphragm film 2A a first resistor 3 ₁ and the second resistor 3 ₃ as opposing surface resistance near the edges are formed and arranged,
Further on the back surface of the diaphragm layer 2A the first resistor opposite to each other in the vicinity of an edge 3 ₁ and the second
Third resistor 3 _second and fourth resistor 3 ₄ as the back surface resistance is formed disposed in a position rotated approximately 90 degrees from the position of the resistor 3 _3.

That is, a pair of resistors 3 ₁ , 3 ₃ arranged opposite to each other are formed on the surface side of the diaphragm film 2 A, and another pair of resistors 3 ₁ , 3 ₃ arranged opposite to each other corresponding to these resistors 3 ₁ , 3 ₃ are arranged. of the resistor 3 _2, 3 ₄ are formed and arranged on the rear surface side of the diaphragm film 2A, moreover resistor 3 ₁ pair, 3 ₃ and the resistor 3 _2, 3 ₄ other pair Si ₃ N ₄ It is configured to be disposed at a position rotated 90 degrees via the film.

These resistors 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄
Is electrically connected by metal electrodes and wiring patterns 4 buried in electrode extraction holes (not shown) so as to form a bridge circuit as shown in FIG. 4 between the Si ₃ N ₄ film laminations constituting the diaphragm film 2A and on the front and back surfaces. It is connected to the.

In such a configuration, when pressure is applied to the diaphragm film 2A, each of the resistors 3 ₁ , 3 ₂ , 3 ₃ and 3 _{4 is applied.}
Compression and tensile stress having substantially the same size occur alternately at the formation position of the resistors, and when the temperature changes, each of the resistors 3 ₁ , 3 ₂ ,
3 _3, 3 ₄ since the magnitude forming position approximately equal compressive or tensile unified stress is generated in, at the time of pressure application, the output is generated, substantially the output does not occur when the temperature changes. As a result, the S / N ratio could be significantly improved.

Next, a description will be given of a method of manufacturing the resistance type pressure sensor element having the above configuration. First, a Si ₃ N ₄ about the surface of the silicon substrate 1A for example, CVD 0.
A first Si ₃ N ₄ film is formed with a thickness of from 0.5 to 0.3 μm. Then a polycrystalline silicon having a thickness of about 0.05~0.4μm thickness by resistor 3 _2, 3 _4, for example, CVD method as a back resistor at a predetermined position on the surface side of the first Si ₃ N ₄ film after forming in it is, formed by the resistors 3 _2, 3 ₄ known Utsushikoku techniques.

Next, on the first Si ₃ N ₄ film, a second Si ₃ N ₄ film serving as a base of the diaphragm is formed to a thickness of about 0.5 to 5 μm by the same method as described above. I do. Then this second
Si ₃ N resistors on the ₄ film as the surface resistivity of polycrystalline silicon 3 _1, 3 ₃ in the same manner about 0.05 to 0.
It is formed in the same manner as described above to a thickness of 4 μm. Next, this second S
A _third film having the same thickness as the first Si ₃ N ₄ film is formed on the i ₃ N ₄ film.
Forming the the Si ₃ N ₄ film.

[0015] Then the resistors 3 _1, 3 _{2, 3} 3, 3 so as to reach the end of the ₄ second Si ₃ N ₄ film and the third Si ₃ N ₄ film or the third Si ₃ N ₄ Form an electrode extraction hole penetrating the film. Next, after these electrode take-out holes are filled with metal electrodes to make electrical connection, the resistors 3 ₁ , 3 ₂ ,
3 _3, 3 ₄ aluminum about by the wiring pattern 4 such as vapor deposition to form a bridge circuit 0.02-2
A film is formed to a thickness of μm. Next, a through-hole 1a is formed by etching from the back surface of the silicon substrate 1A to complete a resistive pressure sensor element.

In the embodiment described above, the four resistors 3 ₁ , 3 ₂ , 3 formed on the diaphragm film 2A are arranged.
_3, 3 _4, in the front and back surfaces of the diaphragm film 2A, resistor 3 _1, 3 ₃ and the resistor 3 _2, 3 ₄ and its longitudinal direction is described as being disposed such that the diaphragm center portion, The present invention is not limited to this, and the same effect as described above can be obtained even when all the _four resistors 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ are arranged in the same direction.

Further, in the above-described embodiment, a silicon substrate is used as a substrate portion, and a silicon substrate is used as a diaphragm portion.
_Although the case where the 3N ₄ film is used has been described, the present invention is not limited to this, and the same effect as described above can be obtained by using a combination of a bulk material and a direct bonding technique.

Further, in the above-described embodiment, the case where the shape of the diaphragm portion is rectangular has been described. However, the present invention is not limited to this. For example, the diaphragm portion may be formed in a circular shape or a polygonal shape. It goes without saying that the same effect as described above can be obtained.

[0019]

As described above, according to the present invention,
By separating the output for pressure from the output change due to the temperature change and the influence from the package, it is possible to detect only the pressure applied to the diaphragm part.
There is an extremely excellent effect that a detection output with a high S / N ratio can be obtained without being affected by an output change due to a temperature change and an influence from a package.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a configuration of a resistance type pressure sensor element according to an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of FIG.

FIG. 3 is a plan view illustrating a configuration of a conventional resistive pressure sensor element.

FIG. 4 is a diagram showing an equivalent circuit of FIG. 3;

[Explanation of symbols]

Reference Signs List 1A Silicon substrate 2A Diaphragm film 3 ₁ First resistor 3 ₂ Third resistor 3 ₃ Second resistor 3 ₄ Fourth resistor 4 Wiring pattern 5 ₁ Input terminal 5 ₂ Input terminal 5 ₃ Output terminal 5 ₄ output terminals

Claims (1)

(57) [Claims] A substrate provided with at least one of a through hole and a depression in one surface; a diaphragm formed on one surface of the substrate; and a substrate facing an edge of the surface of the diaphragm. A first resistor and a second resistor formed by the first and second resistors opposing each other at a position substantially 90 degrees rotated from the position of the first resistor and the second resistor near the edge of the back surface of the diaphragm portion; A third resistor and a fourth resistor formed by
And a wiring pattern for bridge-connecting the first resistor, the second resistor, the third resistor, and the fourth resistor. .