JPH0611403A - Pressure sensor array - Google Patents

Abstract

(57) [Abstract] [Purpose] It is a capacitance type that can be expected to have high sensitivity and high stability, has less parasitic capacitance than the conventional sensor of this type, and has a high density and distance between electrodes. A uniform and highly accurate pressure sensor array is provided. A diaphragm 1 having a plurality of electrodes 11 formed on a semiconductor thin plate, and a semiconductor substrate 2 having a plurality of electrodes 21 facing the electrodes 11 are provided on a semiconductor thin plate corresponding to the electrode pairs. The structure is such that they are joined to each other through the spacer 3 having the through holes 31 formed therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type micro pressure sensor array using a semiconductor diaphragm, which can be used as a pressure sensor for industrial measurement or automatic measurement for automobile or medical use.

[0002]

2. Description of the Related Art Micro pressure sensors using a semiconductor diaphragm are generally classified into a piezoresistive type and a capacitance type.

The piezoresistive type utilizes the piezoresistive effect of polysilicon. A polysilicon resistor is formed on the surface of a diaphragm formed of a silicon substrate adjacent to the diaphragm and acts on the resistor via the diaphragm. The pressure is detected from the change in its resistance value.

The electrostatic capacitance type utilizes a capacitance change due to a distance change of a counter electrode. For example, a pit-shaped recess is formed on the surface of a glass substrate and one electrode is formed on the bottom thereof, and the recess is formed. A thin-plate diaphragm is placed so as to cover the diaphragm, and the other electrode is formed on this diaphragm, and the pressure is detected from the capacitance change between the electrode pair accompanying the deformation of the diaphragm due to the pressure change (for example, the Institute of Electrical Engineers of Japan Shu C109 Volume 12 (Heisei 1) P.820
).

[0005]

In the pressure sensors of the respective types described above, there are reports of two-dimensionally integrated piezoresistive type pressure sensors (S. Saginomiya et.al., Proc. Transducer's.
89 (1989) p.152, or IEICE Transactions C
-II Vol. J73-C-II No.31-37, January 1990), susceptible to temperature and stress, making it difficult to achieve high precision.

On the other hand, in the capacitance type, high sensitivity and high stability can be expected, but it is difficult to make the distance between electrodes uniform,
In particular, there is a problem in the case of forming an array, and there is a drawback that it is difficult to reduce the parasitic capacitance in the conventional structure due to the signal extraction wiring from the electrodes and the like.

The present invention has been made in view of the above points, and is a capacitance type which can be expected to have high sensitivity and high stability, has a small parasitic capacitance, and has a high density and a uniform distance between electrodes. The purpose is to provide a simple pressure sensor array.

[0008]

A structure for achieving the above object will be described with reference to FIGS. 1 and 2 corresponding to an embodiment. A pressure sensor array of the present invention has a plurality of semiconductor thin plates on one surface thereof. The diaphragm 1 having the electrodes 11 ... 11 formed thereon and the semiconductor substrate 2 having a plurality of electrodes 21. It is characterized by being joined to each other through the spacer 3 in which a plurality of through holes 31 ... 31 corresponding to the electrode pairs are formed.

[0009]

The distance between the electrodes is determined by the thickness of the spacer 3, and since the spacer 3 is a semiconductor thin plate, semiconductor fine processing technology can be applied to its processing.
Since it is easy to make the distance between the electrodes uniform and the density can be easily made, and since both the diaphragm 1 and the electrodes on the substrate 2 side are formed on a flat surface, the signal extraction wiring has a parasitic capacitance. Affects little and can achieve the intended purpose.

[0010]

1 is a sectional view of an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof. The diaphragm 1 is a semiconductor thin plate that elastically deforms due to the measured pressure, and is composed of a silicon single crystal plate having a thickness of several tens of μm. On one surface of the diaphragm 1, a plurality of electrodes 11, ... 11, Which are formed by depositing a refractory metal, are two-dimensionally formed.

On one surface of the semiconductor substrate 2 made of, for example, a silicon single crystal, a plurality of electrodes 21 ... 21 each having the same pattern as the electrodes 11 ... The semiconductor substrate 2 and the diaphragm 1 are formed in a three-dimensional shape, and the electrodes 11
.... Spacer 3 so that 11 and 21 ... 21 face each other
Are joined through.

The spacer 3 is formed on a semiconductor thin plate made of silicon single crystal or the like and has electrodes 11 ... 11 and 2 facing each other.
A plurality of through-holes 31 ... 31 are formed so that a gap is formed between the spacers 1 ... 21 and the thickness of this spacer 3 is the distance between the electrodes 11 ... 11 and 21 ... 21. Is prescribed. Around the spacer 3, a step portion 32 is formed so as to project to both front and back sides, and the inner edge of the step portion 32 has the same shape and size as the outer edge of the diaphragm 1 and the semiconductor substrate 2. By inserting the diaphragm 1 and the semiconductor substrate 2 inside the step 32,
Electrode 11 ..., through hole 31 ... 31 and electrode 21 ...
21 are aligned with each other.

An oxide film is formed on each of the joint surfaces of the spacer 3 and the spacers 3 of the diaphragm 1 and the semiconductor substrate 2 except for the portions where the electrodes 11 ... 11 and 21 ... 21 are formed. 1 and the spacer 3, and the semiconductor substrate 2 and the spacer 3 are firmly bonded to each other by fusion bonding. That is, a silicon single crystal having a thin oxide film formed on its surface can be easily and strongly bonded by a high temperature heat treatment at about 1000 ° C., and the electrodes 11 ... 11 and 21 ... 21 are made of refractory metal. Thus, the members 1 to 3 can be individually formed and then integrated.

According to the embodiment of the present invention having the above-mentioned structure, each electrode 11 of the diaphragm 1 is formed as a variable electrode of the capacitance type pressure sensor, and each electrode 2 of the semiconductor substrate 2 is formed.
The diaphragms 1 and 21 also form the counter electrodes.
It is possible to measure a two-dimensional distribution of the measured pressure acting on the. That is, when the measured pressure acts on the diaphragm 1, the formation portion of the electrodes 11 ... 11 is deformed according to the size thereof, and the distance between the electrodes 21. Since the capacitance of each electrode pair changes, the magnitude of pressure at the formation position of each electrode pair can be known from the change in capacitance.

In this structure, a point to be particularly noted is that the distance between the electrodes of each array-shaped sensor is determined by the thickness of the spacer 3, and this makes it possible to easily make all the distances between the electrodes uniform. It will be possible.

In manufacturing the above-described embodiment of the present invention, the through holes 31 of the spacer 3 can be opened by anisotropic etching, and the positioning in the surface direction and the diaphragm 1 can be performed. With respect to the positioning of the electrodes 11 ... 11 and 21 ... 21 of the semiconductor substrate 2, by applying the semiconductor fine processing technology, a highly precise and high density sensor array can be obtained.

Further, after the members 1 to 3 are individually prepared,
Since they can be aligned with each other and integrated at the end, it becomes easy to form a signal processing circuit on the semiconductor substrate 2 to form a one-chip intelligent sensor. However, only the electrodes 21 ... 21 may be formed on the semiconductor substrate 2 and the signal processing circuit may be formed on another substrate. In this case, the degree of freedom in the manufacturing process is increased, and the performance and yield of the signal processing circuit are increased. Can be expected to improve.

The material of the diaphragm 1, the semiconductor substrate 2 and the spacer 3 is not limited to silicon single crystal, but the function required for each member, such as elasticity in the diaphragm 1 and anisotropic in the spacer 3. In view of the fact that it is possible to perform a positive etching, and further considering the joining of each member, it can be said that silicon single crystal is the most suitable material.

[0019]

As described above, according to the present invention,
A semiconductor diaphragm having a plurality of electrodes formed thereon, and a semiconductor substrate having electrodes facing the respective electrodes are formed of a semiconductor thin plate, and a spacer having through holes corresponding to the respective electrode pairs is provided therebetween. Since the electrostatic capacitance type pressure sensor array is configured by bonding them to each other, the distance between each electrode pair is uniquely determined by the thickness of the spacer, and the semiconductor microfabrication technology is applied even when manufacturing the same. Therefore, compared with the conventional pressure sensor array of this type, it is possible to easily obtain a highly accurate and high-density sensor array in which the distance between the electrodes is extremely uniform.

Further, because of its structure, each electrode is formed on a plane, so that wiring for signal extraction is easier and the parasitic capacitance is reduced as compared with the conventional sensor of this type.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is an exploded perspective view thereof.

[Explanation of symbols]

 1 Semiconductor Diaphragm 11 ... 11 Electrode (Variable Electrode) 2 Semiconductor Substrate 21 ... 21 Electrode (Counter Electrode) 3 Semiconductor Spacer 31 ... 31 Through Hole 32 Step

Claims (1)

[Claims] 1. A capacitance-type two-dimensional pressure sensor array using a semiconductor diaphragm, wherein a diaphragm having a plurality of electrodes formed on one surface of a semiconductor thin plate, and a plurality of electrodes facing each electrode on one surface. And a semiconductor substrate having electrodes formed thereon are bonded to each other via a spacer having a plurality of through holes corresponding to the electrode pairs formed on the semiconductor thin plate.