JPH06251672A - Pressure switch and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent leak current generated between two impurity diffused layers which connect the pressure standardized chamber to outside by forming a reverse type impurity layer between the two impurity diffused layers or in the circumference of them. CONSTITUTION:A recessed part 3 to form a pressure standardized chamber 10 is formed by etching a single crystal silicon 6 and a second impurity diffused layer 1 is formed in the recessed part 3 and in the circumference of an impurity diffused layer 2 which is going to be formed afterwards. Glass 7 in which a glass side electrode 8 is formed in the recessed part 3 side of a single crystal silicon 6 and the single crystal silicon 6 are put together to give the pressure standardized chamber 10. A metal contact point 4 to make a contact with the electrode 8 on the diffused layer 2 in the pressure standardized chamber 10 is formed. An aluminum pad 5 corresponding to the electrode 8 and an aluminum pad 5 corresponding to the metal contact point 4 are formed on the upper face of the diffused layer 22 in the outside of the pressure standardized chamber 10.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention generally relates to the automobile industry,
The present invention relates to a pressure switch used for a device or product that requires pressure detection in a product in the machine industry and a manufacturing method thereof.

[0002]

2. Description of the Related Art As a structure of a conventional general pressure switch, an N type having a diaphragm partly provided with a metal contact and a boron diffusion layer for outputting a signal from the metal contact to the outside. Corresponding to the base material made of single crystal silicon and the diaphragm formed on the single crystal silicon base material, a pressure reference chamber is formed between the diaphragm and the metal contact point of the diaphragm and the displacement of the diaphragm. A glass substrate having a glass substrate-side electrode forming an electrically conductive switch is adhered to the base material to form a pressure switch.

Further, transmission of an electric signal between the glass substrate side electrode and the outside is also performed through the boron diffusion layer, and further, the glass substrate side electrode is used together with the boron diffusion layer for the metal contact of the diaphragm. The boron diffusion layers were also formed on the silicon substrate.

[0004]

In a conventional pressure switch, an impurity diffusion layer such as boron diffusion for electrically connecting a metal contact on a diaphragm in the pressure reference chamber and the outside of the pressure reference chamber, and a pressure reference chamber. Between or around the impurity diffusion layers (hereinafter referred to as two impurity diffusion layers) such as boron diffusion that electrically connect the glass substrate side electrode with the outside of the pressure reference chamber, there is an electrical insulation boundary. Since it was done with the single crystal silicon as the base material, the current easily leaks between the above two impurity diffusion layers, and the pressure switch is turned off.
The resistance at that time often showed a low resistance of several tens K to several hundred KΩ.

[0005]

In order to solve the above-mentioned problems, an impurity diffusion layer opposite to the above-mentioned impurity diffusion layer is formed between or around two impurity diffusion layers connecting the pressure reference chamber and the outside. In addition, the dose amount of the inverted impurity diffusion layer was made larger than the dose amount of the substrate.

[0006]

With the structure of the present invention, when a current is passed through the pressure switch, a leak current between the two impurity diffusion layers connecting the pressure reference chamber and the outside can be prevented by the inverted impurity diffusion layer. The resistance when the pressure switch is turned off does not show a low resistance of several tens K to several hundred KΩ.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pressure switch according to the present invention will be described below with reference to the drawings. 1 and 2 are views showing an embodiment of the structure of a pressure switch according to the present invention. FIG. 1 is a schematic plan view of a silicon base material having a diaphragm showing a state before joining a glass substrate, and FIG. 2 shows a sectional view after joining the glass substrate.

The pressure switch according to the present invention is characterized in that the concave portion 3 for forming the pressure reference chamber 10 is formed by etching a single crystal silicon 6 which is a gas, and the concave portion 3 and the impurity diffusion formed thereafter are formed. A second impurity diffusion layer 1 is formed around the layer 2 to prevent current leakage. Then, the pressure reference chamber 10 is formed by bonding the glass 7 having the glass side electrode formed on the concave side of the single crystal silicon 6 and the single crystal silicon 6 to each other. Then, the metal contact 4 is located in the pressure reference chamber 10 and on the first impurity diffusion layer 2 on the upper surface of the single crystal silicon 6 for contacting the glass side electrode 8 in the pressure reference chamber 10.
Is formed. Further, on the upper surface of the first impurity diffusion layer 2 outside the pressure reference chamber, an aluminum pad 5 corresponding to a glass substrate side electrode for transmitting an electric signal from the outside to the pressure switch, and the single crystal. An aluminum pad 5 corresponding to the metal contact 4 on the silicon 6 side is formed.

Next, FIGS. 3 (1) to 3 (5) and FIG. 4 (1)
(5)-(5) shows the manufacturing method of the pressure switch by this invention. In FIG. 3A, the recess 3 for forming the pressure reference chamber is formed in the single crystal silicon 6 by dry etching. The depth of the recess 3 at this time is several μ.
m. In FIG. 3B, a silicon oxide film 11, a nitride film 12, and a silicon oxide film 13 are formed on the back surface of the single crystal silicon 6 facing the recess. The silicon oxide film 11 functions to improve the adhesion between the nitride film 12 and the single crystal silicon 6. The nitride film 12 functions as a mask when etching the single crystal silicon 6 in a later step. Further, the silicon oxide film 13 functions as a patterning mask for the nitride film 12.

In FIG. 3C, the nitride film 12 is patterned using the silicon oxide film 13 formed in FIG. 3B as a mask, and the silicon oxide film 11 is etched using the patterned nitride film 12 as a mask. This is a step of removing the silicon oxide film 13. Figure 3 (4) shows
This is a step of forming the second impurity diffusion layer 1 for preventing current leakage by ion implantation using the resist as a mask. FIG. 3 (5) shows a step of forming a first impurity diffusion layer 2 having a shape opposite to that of the impurity diffusion layer 1 inside the impurity diffusion layer 1 formed in FIG. 3 (4).

FIG. 4A shows a step of forming a metal contact 4 by sputtering a metal material for patterning. The metal contact 4 performs a switching operation as a pressure switch by coming into contact with a glass-side electrode formed in a later step. FIG. 4B is a step of forming a pad 5 by sputtering and patterning a metal thin film such as aluminum in order to output a switch operation signal to an external device. Figure 4
(3) is a step of joining the glass substrate 7 on which the glass side electrode 8 is formed by previously sputtering and patterning a metal thin film on the upper surface, and the single crystal silicon 6 completed by the steps up to FIG. 4B. .

FIG. 4 (4) shows the glass substrate 7 in FIG. 4 (3).
A step of etching the single crystal silicon 6 with potassium hydroxide or the like according to the mask of the nitride film 12 in order to form the diaphragm 9 on the back surface of the single crystal silicon 6 in a state where the single crystal silicon 6 and the single crystal silicon 6 are bonded together, Figure 4 (5)
In the process of completing the semiconductor pressure switch, a part of the glass is cut in order to output an electric signal to an external device, and the state is diced into a chip size as the semiconductor pressure switch.

[0013]

As described above, according to the pressure switch of the present invention, both impurities are diffused when a current is applied to the impurity diffusion layer for the electrode on the glass substrate side and the impurity diffusion layer for the metal contact formed on the single crystal silicon. It is possible to prevent a leak current generated between the diffusion layers, and to clearly determine the ON / OFF state of the pressure switch.

Therefore, as a result of these, various effects can be obtained such that the reliability as a pressure switch can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a planar configuration of single crystal silicon of a pressure switch according to the present invention.

FIG. 2 is a sectional view showing the structure of a pressure switch according to the present invention.

FIG. 3 is a process drawing showing the manufacturing method of the pressure switch according to the present invention.

FIG. 4 is a process drawing showing the method of manufacturing the pressure switch according to the present invention.

[Explanation of symbols]

 1 Second Impurity Diffusion Layer 2 First Impurity Diffusion Layer 3 Recess 4 Metal Contact 5 Aluminum Pad 6 Single Crystal Silicon 7 Glass Substrate 8 Glass Side Electrode 9 Diaphragm 10 Pressure Reference Chamber 11 Silicon Oxide Film 12 Nitride Film 13 Silicon Oxide Film

Claims (2)

[Claims] 1. A single crystal silicon having a recess for forming a pressure reference chamber and a metal contact in the recess, and a diaphragm for pressure sensing formed on a back surface corresponding to the recess forming surface, and a glass substrate. A pressure switch formed by forming a metal thin film on a surface of the concave portion facing the concave portion, and joining the single crystal silicon and the glass substrate so that the metal contact on the single crystal silicon and the metal thin film on the glass substrate face each other. In order to transmit an electrical signal from an external device, the impurity diffusion layer that electrically connects the pressure reference chamber and the outside of the pressure reference chamber is divided into a glass-side electrode and a metal contact for the single crystal. A pressure switch, wherein the impurity diffusion layer is formed on silicon, and an impurity diffusion layer having a dose amount higher than an impurity concentration in the single crystal silicon is formed around the impurity diffusion layer. 2. A step of forming a recess of several μm in single crystal silicon, a step of forming a silicon oxide film on a back surface facing the recess of the single crystal silicon, and a nitride film formed on the silicon oxide film. A step of forming a silicon oxide film for patterning on the nitride film, a step of etching and patterning the silicon oxide film,
According to the patterned silicon oxide film, a step of etching the nitride film, a step of etching the silicon oxide film, a step of impurity-diffusing with a resist mask on the single crystal silicon, and a step of removing the impurity diffusion layer after removing the resist. Inside, a step of forming an impurity diffusion layer having a shape opposite to that of the impurities by a resist mask, a step of forming a metal contact in a recess for forming the pressure reference chamber, and a transmission of an electric signal with an external device. In order to perform the step, a step of forming a pad outside the recess, a step of bonding a glass substrate on which a metal thin film is formed in advance and single crystal silicon with electrodes of each other facing each other, and single crystal silicon by the nitride film mask. Etching to form a silicon diaphragm and dicing into a size to be used as a pressure switch. Method for producing a pressure switch comprising the step of graying.