JPH06112506A - Manufacture of pressure switch - Google Patents

Abstract

PURPOSE:To make it possible to prevent a current from leaking as well as to improve a reliability becoming to a pressure switch by a method wherein when a metallic contact and a pad are formed, a part, which does not require a metal film, is covered with a nitride film or the like and a passivation film is formed at a part, on which a single crystal silicon substrate is exposed, in the peripheral part of the pad. CONSTITUTION:A boron diffused layer 3, which is used as an electrode pattern, is formed in a single crystal Si substrate 1 with a recessed part 2 formed therein and after each Si oxide film 4 is formed on both surfaces of the Si substrate 1, nitride films 5 and upper Si oxide films 6 are respectively formed on the respective surfaces of both Si oxide films 4. Then, the surfaces of both oxide films 6 are patterned and after the films 5 are etched using the films 6 as masks, the films 6 are removed and the lower oxide films 4 are etched. Then, a contact electrode 9 is formed on one part of the layer 3 in the exposed recessed part 2 and a pad 12 for electrode take-out is formed on one part of the layer 3 outside of the recessed part 2. Then, the periphery of the pad 12 including its surface is masked and after the films 5 and 4 on the surface of the Si substrate 1 are etched, a glass film 15 is bonded on the side of the recessed art 2 formation surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a pressure switch for detecting pressure in the automobile industry and the like.

[0002]

2. Description of the Related Art In the conventional method of manufacturing a pressure switch, sputtering of a metal contact or sputtering for forming a pad is performed directly on the surface of single crystal silicon. Further, the finally completed pressure switch had an exposed portion where the surface of the single crystal silicon was in direct contact with the outside air.

[0003]

In the pressure switch manufactured by the conventional method, an etching residue may occur when forming a metal contact or a pad, and a current may leak.
In addition, since the single crystal silicon is exposed in the peripheral portion of the pad, the pad is easily contaminated, and the contamination may cause current leakage.

[0004]

According to the method of manufacturing a pressure switch of the present invention, in forming a metal contact and a pad, a nitride film is formed so as not to be directly sputtered on the single crystal silicon at a portion where the metal sputtered film is unnecessary. Etc., and the nitride film and the like were removed after the metal contacts and pads were formed.
In addition, a passivation film made of a nitride film, a silicon oxide film, or the like was formed in the portion where the single crystal silicon was exposed in the peripheral portion of the pad.

[0005]

When the pressure switch is manufactured by the manufacturing process as described above, it is possible to prevent the etching residue of an unnecessary portion at the time of forming the metal contact and the pad, so that the leakage of current can be prevented. Further, since a passivation film made of a nitride film, a silicon oxide film, or the like is formed in a portion where the single crystal silicon is exposed in the peripheral portion of the pad, it is possible to prevent current leakage due to contaminants.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a process diagram showing a method of manufacturing a pressure switch according to the present invention. As the manufacturing process of the pressure switch,
First, the concave portion 2 having a depth of several μm is formed on the surface of the single crystal silicon 1. Then, a boron diffusion layer 3 is formed in the recess 2 and a part of the single crystal silicon 1. This state is shown in FIG.

Next, a silicon oxide film 4 is formed on both surfaces of the single crystal silicon 1. This is sandwiched between the single crystal silicon 1 and the nitride film 5 because the nitride film 5 formed in FIG. 1C strongly adheres to the single crystal silicon 1. The nitride film 5 later functions as the passivation film of the present invention. It also functions as a mask for forming a diaphragm in a later step.

In the step of FIG. 1D, a silicon oxide film 6 is formed on the upper surface of the nitride film 5. This silicon oxide film 6 is
It is used when patterning the nitride film 5. FIG. 2 shows how the silicon oxide film 6 is formed as a mask at that time.
It shows in (1). For patterning the silicon oxide film in FIG. 2A, a hydrofluoric acid-based etching solution is used. Conventionally, the patterning of the silicon oxide film 6 was performed only on the diaphragm forming surface side, but in the manufacturing process of the present invention, the electrode forming surface side is also patterned.

In FIG. 2B, the nitride film 5 is etched by the patterning mask of the silicon oxide film 6 performed in FIG. 2A. Both sides of the nitride film 5 are etched by hot phosphoric acid. FIG. 2C shows a state in which the silicon oxide film 4 and the silicon oxide film 6 are simultaneously etched using a hydrofluoric acid-based chemical.

In FIG. 2 (4), a metal thin film 7 of titanium, nickel, chromium, gold or the like, which becomes a metal contact, is sputtered on the electrode formation surface. In the conventional process, since the nitride film 5 and the silicon oxide film 6 do not exist on the electrode formation surface, the metal thin film is directly sputtered on the single crystal silicon 1. The directly sputtered metal thin film caused an etching residue on the single crystal silicon 1, causing a current leak. Therefore, this nitride film 5 leaves a metal thin film directly in an unnecessary portion so as not to be sputtered. Then, this metal thin film becomes the metal contact 9 in the pressure switch.

As shown in FIG. 2 (4), a portion for forming a metal contact is patterned by using a photoresist 8 and the metal thin film is etched to have a diameter of several tens μm and a height of several thousand Å. The metal contact 9 is formed. At this time, the photoresist on the metal contact is left as it is. This is shown in FIG. 2 (5).

Further, in FIG. 3A, a metal thin film 10 of aluminum or the like is sputtered on the electrode formation surface to form a pad for taking out the electrode to the outside. It functions to prevent contact with the single crystal silicon 1. Moreover, after sputtering on the electrode formation surface, patterning is performed using the photoresist 11.

In FIG. 3B, the metal thin film 10 made of aluminum or the like serving as a pad material is etched according to the photoresist pattern formed in FIG. 3A. Aluminum is etched with a mixed aqueous solution of phosphoric acid / nitric acid / acetic acid. Further, in FIG. 3C, a photoresist 13 is patterned on the nitride film 5 around the pad, and the nitride film 5 and the silicon oxide film 6 are etched by dry etching. Then, as shown in FIG. 3 (4), the photoresists 8, 11, and 13 are removed with an acid, and bonded to the glass 15 on which the electrode 14 is formed in advance. And Figure 3
As shown in (5), the diaphragm forming surface side is provided with the nitride film 5
Etching according to the patterning. By using the manufacturing process as described above, it is possible to prevent current leakage and manufacture a highly reliable pressure switch.

[0014]

According to the method of manufacturing a pressure switch of the present invention, leakage of current can be prevented and the reliability of the pressure switch is improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a manufacturing process according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a manufacturing process according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a manufacturing process according to an embodiment of the present invention.

[Explanation of symbols]

1 Single Crystal Silicon 2 Recess 3 P ⁺ Diffusion Layer 4 Silicon Oxide 5 Nitride 6 Silicon Oxide 7 Metal Thin Film 8 Photoresist 9 Metal Contact 10 Metal Thin Film 11 Photoresist 1 Pad 13 Photoresist 14 Electrode 15 Glass

Claims (1)

[Claims] 1. A step of forming a boron diffusion layer serving as an electrode pattern on a recess formation surface side of single crystal silicon having a recess formed on one surface, and a lower silicon oxide film is formed on both surfaces of the single crystal silicon. The step of forming a nitride film on the surface of the lower silicon oxide film formed on both surfaces of the single crystal silicon, the step of forming an upper silicon oxide film on the surface of the nitride film, and Patterning both surfaces of the silicon oxide film, etching the nitride film using the upper silicon oxide film as a mask, removing the upper silicon oxide film, and etching the lower silicon oxide film, and the etching A step of forming a contact electrode on a part of the boron diffusion layer in the recess exposed by
Forming a pad for taking out an electrode on a part of the boron diffusion layer outside the concave portion; masking the periphery including the pad surface and etching the nitride film and the silicon oxide film on the surface; A method of manufacturing a pressure switch, which comprises the step of bonding glass to the concave formation surface side of.