JPS59150480A - Semiconductor pressure conversion device - Google Patents

Abstract

PURPOSE:To reduce the temperature change of the output voltage of a bridge circuit by eliminating the inequality of the reverse bias voltage between each diffused layer and thus enhance the accuracy by making equal the distance between a reverse bias electrode and a diffused resistance layer. CONSTITUTION:A thin diaphragm 42 is formed by etching, etc. from the back surface of a single crystal plate 41, and the diffused resistance layers 43 (431,... 434) are provided on the diaphragm. The reverse bias electrode 44 is provided at the center of the diaphragm 42 at the same distance from each diffused resistance layer 431, 432, 433, and 434. The reverse bias voltages impressed on the P-N junctions between said plate 41 and said layers 43 via said electrode 44 become equal, and therefore the temperature change of the output voltage becomes small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor pressure transducer that measures fluid pressure by utilizing the piezoresistance effect of a semiconductor.

[Prior art and its problems]

By applying semiconductor planar technology, a thin diaphragm is provided on a part of a semiconductor single crystal plate such as silicon or germanium, and a diffused resistance layer is formed as a pressure-sensitive element on this diaphragm. Pressure conversion is performed using the piezoresistance effect of the thin diaphragm. The device has been put into practical use.

The schematic structure of this example is shown in FIG. In the figure, reference numeral 1 is, for example, an n-type silicon single crystal plate, and a thin diaphragm 2 is provided in the center of the plate, and a p-type diffusion layer 3 (3, 32, . . .
・) is formed. The surface is covered with an insulating layer 4, and an electrode wiring layer 5 made of A/etc. is disposed thereon. The electrode wiring layer 5 contacts the ends of the single crystal plate 1 and the diffused resistance layer 3 through contact holes provided in the insulating layer 4, and is used for internal wiring of the single crystal plate 1 and the diffused layer 3 and for taking out the electrode to the outside. It plays the role of a terminal. Therefore, the lead wires 6 (68, 68, 68, 64 are connected to the diffusion 11 (
6. Lead wire connecting to anti-layer 3; is a lead wire tangential to the single crystal plate 1. ) is bonded. Such a pressure conversion board 10 is adhesively fixed to a fixing base 7 made of silicon, for example, with an adhesive 9. The fixing base 7 is provided with a through hole 8, and the pressure p of the fluid flowing into the through hole 8 causes the diaphragm 2 to deform.

For actual fluid pressure measurement, for example, two fixed resistors pt, h, and 33.32R are added to the pressure conversion board 10.
, , R, form a bridge circuit. In this case, the diffused resistance 3. ．． 32, one of which has a resistance value that increases with the fluid pressure p, and the other whose resistance value decreases with the fluid pressure p. Such resistance IIi! The anisotropy of the change is determined by which region of the diaphragm 2 and in what pattern the diffused resistance layer is provided. At this time,
In order to make the output voltage ΔV of the bridge circuit less likely to be affected by external electrical noise, etc., for example, as shown in FIG. 1, a lead wire 6. It is connected to power supply E via. Then, a reverse bias voltage is applied to the pn junction between the n-type single crystal plate 1 and the p-type diffused resistance layer 3.

However, in the conventional pressure transducer substrate, for example, as shown in FIG. 2, a voltage for reverse bias is applied to the single crystal plate 31.
3s and 334 were different. For this purpose, the respective diffused resistance layers 331, 332, 338, 33. There was a difference in the reverse bias electric ratio applied to the , which resulted in a difference in the temperature characteristics of each folded layer, resulting in a large temperature change in the output voltage Δ■ of the bridge circuit.

[Purpose of the invention]

The present invention has been developed in view of the above-mentioned points, and it is an object of the present invention to provide an accurate semiconductor pressure transducer in which the temperature change in the output voltage △■ of the bridge circuit is small.

[Summary of the invention]

This invention provides a p-
An electrode provided on a semiconductor single crystal plate to apply a reverse bias voltage to the n-junction (hereinafter referred to as a reverse bias electrode).
It is characterized in that the distances between and the respective diffused resistance layers are made equal. By making the distance between the f-saving bias it pole and the diffused resistance layer equal, the imbalance in reverse bias voltage between each diffused layer caused by the resistance of the single crystal plate is eliminated, and the output voltage of the bridge circuit is improved. △V (hereinafter output 'lip pressure△
■ and sing. ) to reduce the temperature change.

〔Effect of the invention〕

Compared to conventional semiconductor pressure transducers, the semiconductor pressure transducer according to the present invention is more sensitive to temperature changes in the output voltage △■, especially when no fluid pressure is applied to the diaphragm.
(This is called zero point output) temperature change has become smaller.

Conventionally, since the distance between the reverse bias electrode and the diffused resistor was not equal, there was a difference in the temperature change of the zero point output depending on which diffused resistor layer was used even within the same semiconductor pressure transducer angle, and the demand for the zero point output was affected. The width of a 1 degree change in ambient Y blackness was 1.2% FS when the ambient Y blackness changed from 1°C to 80°C. According to the present invention, no matter which diffused resistance layer is used, there is no difference in the temperature change in zero point output, and the thickness of the zero point temperature change is also 1.0%.
FS became smaller.

[Embodiments of the invention]

Embodiments of the present invention will be explained below with reference to the drawings.

FIG. 3 is a schematic diagram of a semiconductor pressure transducer according to the present invention. A thin diaphragm 42 is formed from the back side of the single crystal plate 41 by etching or the like.
A diffused resistance layer 43 (43, . . . 434) is provided on top of the resistive layer 2 . The reverse bias electrode 44 is a diaphragm whose distance is equal from each diffused resistance layer 43h432.433.434.

It is provided in the center of 42. Therefore, the reverse bias voltage applied to the pn junction between the single crystal plate 4 and the diffused resistance layer 43 through the bias lightning pole 44 becomes equal, and the temperature change in the output voltage ΔV becomes small.

[Other embodiments of the invention]

FIG. 4 shows another embodiment. Implementation step 1 shown in Figure 3
1 has a simple shape, but since the 5p-bias electrode 44 is located at the center of the diaphragm 42, it is not possible to connect a surface lead wire to it. Therefore, diaphragm 4
Wiring must be done from the reverse bias voltage pole 44 at the center of 2 to the thick periphery of the crystal 41 using a metal wire layer such as A/2 or a low-resistance P wiring layer, as shown in FIG. In the embodiment, each diffused resistance layer 53. Reverse bias electrodes 54. - No. 54 are provided.

In the embodiment shown in FIG. 5, the diffusion resistance layer is 6.31 to 6:3.
A wedge 64 is provided on the rectangular reverse bias 7 so as to surround the diaphragm 62 and the diaphragm 62. The shape of the reverse bias electrode 64 is not limited to a rectangle, but may be circular or any other shape as long as it satisfies the condition that the distance from the valley diffusion resistance layer is reasonable.

In the embodiment shown in FIG. 6, the diffused resistance 1? I 73 +
734 are concentrated in a portion of the diaphragm 72.

On the other hand, the reverse bias electrode 74 is provided on the opposite side (1111) of the diffusion resistance layer of the single crystal plate 71, and the distance between the reverse bias electrode 74 and each diffusion resistance layer 73. By making the distances larger than the difference between the resistance layers 73. to 73., the effect is substantially the same as making the distances between the reverse bias electrode 74 and each of the diffused resistance layers 73. to 734 equal. .

@7 In the embodiment shown in Figure 7, the diffused resistance layer 83. One reverse bias electrode surrounds one diffused resistance layer, such that a reverse bias electrode 841 is provided around a reverse bias electrode 831. The shape of the f bias electrode is not limited to a rectangle, but may be any shape as long as the distances between the diffused resistance layer and the reverse bias electrode are equal. Alternatively, two or more diffused resistance layers may be surrounded by a reverse bias electrode or pole.

In the embodiment shown in FIG. 8, a P separation layer 95 surrounds the diffused resistance layer 93 and electrically isolates it from other diffused resistance layers.
A reverse bias electrode 94 is provided within the isolated island 96. In this case, the shape of the islands 96 separated by the separation layer 95 of P is such that if the distance between the diffusion resistance layer 93 and the reverse bias 11L pole 94 in each divided island ( ) 6 is equal, each The isolated islands 96 may have any shape. Also, in this embodiment, contrary to the previous example, the distance between the diffused resistance layer 93 and the reverse bias electrode 94 in each separated island 96 is changed in a fi911N manner,
It is also possible to control the output voltage △■, and the diffusion resistance layer 9
3 is a separation layer 95 and 41. Since they are gaseously separated, each reverse bias electrode 4. The output voltage ΔV can also be controlled by changing the reverse bias voltage applied every .about.944.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the general structure of Kento's semiconductor pressure transducer (lower side) and a measurement circuit (upper side) in which this pressure transducer is assembled into a bridge circuit, and Figure 2 shows its diffusion. A plan view showing the arrangement of the resistance layer and the reverse bias electrode, Figure @3 is a plan view showing the arrangement of the diffused resistance layer and the reverse bias electrode of the force transducer according to the present invention. ,
FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are plan views showing pressure transducers according to other embodiments of the present invention. 1.31.41.51.61.71.81.91...
Single crystal plate 2.32.42.52.62.72.82.9
2... Thin diaphragm 3.33.43.53.6
3.73.83.93... Diffused resistance layer 4゛°° Insulating layer 5... Electrode wiring layer 6... Lead wire
7...Identification stand 8...1 through hole 9
...Adhesive 10...Pressure conversion board 34.44.51.64.74.84.94...Reverse bias electrode 95...m1 layer for P 06...
Separated Shimashiro FLT + Hitoben baseball player Kensuke Chika (
(1 person) Figure 1 r Figure 2 5 3 Figure 4 3-J

Claims (1)

[Claims] In a semiconductor pressure transducer device, a semiconductor crystal plate is provided with a thin part deformed by fluid pressure in the center thereof, and a diffused resistance layer as a pressure sensitive element is formed in the thin part, between the single crystal plate and the diffused resistor. A semiconductor pressure transducer device characterized in that when applying a reverse bias pressure of 10 to the p-n junction of the semiconductor device, the distance between the electrode provided on the i1 crystal plate and the diffused resistor is made equal.