JPH06176671A - Semiconductor pressure switch - Google Patents

Abstract

PURPOSE:To provide a semiconductor pressure switch of high precision and high reliability by providing a reference electrode on a pressure-receiving dia phragm and a contact electrode on the projecting portion of a glass substrate inside a sealed chamber which is formed by a silicon substrate and the glass substrate. CONSTITUTION:A pressure-receiving diaphragm 11 is formed in the recessed portion 2 of a silicon wafer 1. A glass substrate 9 is joined to the silicon wafer 1 and a sealed chamber is formed inside the recessed portion 2. A contact electrode 14 is provided within the sealed chamber and connected to a boron electrode 3 having a bonding pad 8. A reference electrode 12 provided on the diaphragm 11 via an oxide film is brought into and out of contact with the contact electrode 14 by distortion of the diaphragm 11 which corresponds to pressure changes from outside the sealed chamber, so as to turn a switch on and off. In this pressure switch, a projecting portion 13 is formed on that surface of the glass substrate 9 which is opposite to the reference electrode 12, and the contact electrode 14 is formed via the projecting portion 13. Peeling of the film on the diaphragm 11 is thus prevented and the amount of deflection of the film is made even to enhance precision.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the structure of a semiconductor pressure switch.

[0002]

2. Description of the Related Art A conventional semiconductor pressure switch will be described with reference to FIG. 3 (plan view) and FIG. 4 (cross-sectional view). 1 is thickness 52
5 μm, N-type silicon substrate, 2 is a recess etched by about 3 μm by a plasma etching device,
The back side of the recess is etched to a thickness of about 20 μm.
The thinned diaphragm 11 is formed. Three
Is a boron electrode diffused by boron ion implantation. Further, an oxide film 4 is formed as an underlying insulating film of the wiring electrode on the concave portion 2, and a convex portion 5 of polycrystalline silicon formed by LPCVD is further formed on the oxide film 4. A contact electrode 6 of Au and Cr having a thickness of about 20 μm formed by sputtering is formed on the convex portion 5 and is connected to the boron electrode 3. Reference numeral 8 is an Al bonding pad.

A reference electrode 10 of Au or Cr formed by sputtering is formed on one of the glass substrates 9. The glass substrate 9 on which the reference electrode 10 is formed and the silicon substrate 1 are set so that the contact electrode 6 and the reference electrode 10 face each other, and the recess 2 is formed by anodic bonding.
The inside and the atmosphere side are hermetically sealed and bonded.

[0004]

However, when minute convex contact points are formed on the diaphragm by a metal such as Au or Cr, the pressure can be detected for a while, but the diaphragm changes the pressure on the atmosphere side. Since it moves with time, peeling of the film on the convex portion is likely to occur, which causes a problem in reliability, and there is a difference in the deflection amount between the wiring part on the diaphragm and the part without wiring. Therefore, there is a problem in that the deflection of the diaphragm is not uniform and the accuracy is poor.

[0005]

In order to solve the above problems, the present invention uses the electrode on the diaphragm side as a reference electrode, deposits a metal film on the entire surface of the recess, and forms a contact electrode on the glass substrate side. .

[0006]

With the above structure, since the electrode formed on the diaphragm is not a minute convex contact electrode, there is no risk of peeling of the film and reliability is high, and the amount of deflection of the diaphragm is uniform. A highly accurate semiconductor pressure switch can be formed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor pressure switch of the present invention will be described below with reference to FIGS. In the drawing, 1 is an N-type silicon substrate having a thickness of 525 μm, 2 is a recess formed by etching the silicon substrate by about 3 μm by a plasma etching apparatus, and further etching is performed from the back surface side of the recess to thereby obtain a thickness of about A 20 μm diaphragm is formed. 3 is a boron electrode diffused by boron ion implantation. Further, an oxide film 4 is formed as an insulating film on the base of the wiring electrode on the concave portion 2, and Au, which is formed by sputtering on the oxide film,
A Cr reference electrode is formed. Reference numeral 8 is an Al bonding pad.

On one glass substrate 9, about 10 μm was formed by etching with hydrofluoric acid using a Au sputtered film as a mask.
The recess 13 is formed. Then, on the convex portion 13, a contact electrode 1 for electrically connecting with the boron electrode 3 is formed.
4 is formed by sputtering Au and Cr.

The glass substrate 9 on which the contact electrodes are formed and the silicon substrate on which the reference electrode 12 is formed are set so that the respective electrodes face each other, and are sealed and bonded to the inside of the recess 2 and the atmosphere side by anodic bonding. It The manufactured semiconductor pressure switch was put in a pressure vessel and pressurized to confirm the continuity between the two bonding pads 8.
Continuity was confirmed at 2.0 kg / cm ² . Further, the pressurization measurement was repeated 100 times and the variation in the conducted pressure was measured, and all the pressures were ± 0.025 kg / cm.
It was within ² . Further, even if the pressurization was performed 20,000 times, no breakage or the like occurred, and there was no change in the value of the conducting pressure.

As described above, in the pressure switch having the structure according to the present invention, it is possible to manufacture a semiconductor pressure switch with high accuracy and high reliability such as durability.

[0011]

According to the present invention, since the electrode on the diaphragm is not a minute convex contact electrode, there is no fear of film peeling and the reliability is high, and the deflection amount of the diaphragm is uniform, so that the accuracy is high. A good semiconductor pressure switch is now available.

[Brief description of drawings]

FIG. 1 is a plan view of a semiconductor pressure switch of the present invention.

FIG. 2 is a sectional view of the semiconductor pressure switch of the present invention.

FIG. 3 is a plan view of a conventional semiconductor pressure switch.

FIG. 4 is a sectional view of a conventional semiconductor pressure switch.

[Explanation of Codes] 1 Silicon wafer 2 Recessed portion 3 Boron electrode 4 Glass substrate 11 Diaphragm 12 Reference electrode 13 Convex portion 14 Contact electrode

Claims (1)

[Claims] 1. A silicon substrate having a pressure receiving diaphragm inside a recess is joined to a glass substrate to form an airtight chamber inside the recess, and the pressure receiving diaphragm is distorted by a pressure change from the outside of the airtight chamber. In the pressure switch for turning on / off the switch by, the reference electrode is formed on the diaphragm inside the recess forming the airtight chamber, the protrusion is formed on the glass substrate surface facing the reference electrode, and the protrusion is formed. A semiconductor pressure switch characterized in that a contact electrode is formed through the semiconductor pressure switch.