JPH0553096U - pressure switch - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a very small pressure switch capable of detecting pressure in several stages with one diaphragm. [Structure] A recess is formed in a glass substrate to make steps, and contacts are provided at positions corresponding to the steps on a diaphragm so that the contacts come into contact with each other in stages, and pressures of several steps are detected.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a pressure switch.

[0002]

[Prior Art]

 FIG. 3 shows a schematic cross-sectional view of a conventional switch that detects pressure in several stages. Reference numeral 1 denotes a silicon wafer, and a plurality of diaphragms 10 and 11 having different outer diameter sizes formed by thinning the silicon wafer 1 by etching and cavities 12 and 13 are formed on the opposite sides of the etched portions of the diaphragms 10 and 11, A contact electrode is provided in this cavity. Reference numeral 4 denotes a glass substrate on which a reference electrode is formed, which is bonded to the silicon wafer 1 by anodic bonding. Then, the diaphragm 10 is bent by pressurization, the contact electrode 14 on the large-diameter cavity 12 and the reference electrode 16 on the glass substrate 4 are first brought into contact with each other, and further pressurization causes the diaphragm 11 to have a small-diameter cavity. The contact electrode 15 on the reference electrode 13 and the reference electrode 17 come into contact with each other to establish electrical conduction, and as a result, the mechanism is such that the sensing can be performed stepwise. Since the sizes of the diaphragm 10 and the diaphragm 11 are different as described above, a difference in the amount of deflection of the diaphragm is caused, and the pressure at which the contact electrode and the reference electrode contact each other is different, so that the pressure is detected in several stages.

[0003]

[Problems to be solved by the device]

 However, when forming a plurality of diaphragms and detecting pressure in several stages, it is possible to perform detection, but there is a drawback that the proportion of the diaphragm portion becomes large and consequently the chip size becomes large. It was

[0004]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention forms a recess on the glass substrate side to form a step, and a contact is provided at a position on the diaphragm corresponding to the step of the glass substrate to make a stepwise contact. The pressure of several stages can be detected.

[0005]

[Action]

 With the structure as described above, it is possible to detect pressure in several stages with one diaphragm, and the chip size can be made small.

[0006]

【Example】

 An example of the manufacturing procedure of the pressure switch according to the present invention will be described with reference to a schematic sectional view (FIG. 1) and a plan view (FIG. 2). First, a negative type photoresist is applied to a single crystal silicon wafer 1 having a thickness of 525 μm and a plane orientation (100), and exposure and development are performed so that the resist in the portion to be the cavity 3 is removed. After the development is completed, the silicon wafer 1 is etched by plasma etching to have an outer size of 1 × 1 mm and a depth of 1 μm, and the resist is peeled off to form a cavity 3. Then, a silicon nitride film of about 0.1 μm is formed on both sides of the silicon wafer 1 by a CVD apparatus, and a nitride film is formed on the opposite side of the cavity 3 with hot phosphoric acid at about 150 ° C. so as to form the shape of the diaphragm 2. Pattern. After the completion of the patterning of the nitride film, the silicon wafer 1 is immersed in a 35 wt% potassium hydroxide aqueous solution at about 90 ° C. for about 3 hours and 30 minutes, and the silicon wafer 1 is anisotropically etched by 500 μm to form a diaphragm 2 of about 25 μm. Form.

Next, gold (Au) and chromium (Cr) are deposited on the surface of the cavity 3 side by sputtering and patterned to form two contact electrodes 5 and 6. On the other hand, the glass substrate 4 was etched with a mixed solution of hydrofluoric acid and nitric acid using Au and Cr as a mask material to form a concave portion 7 having an outer size of 0.5 × 0.5 mm and a depth of 0.3 μm. Form. Then, the Au and Cr masks are peeled off, Au and Cr are deposited again by sputtering, and the reference electrodes 8 and 9 are patterned.

The silicon wafer 1 in which the cavity 3 and the contact electrodes 5 and 6 are formed and the glass substrate 4 in which the recess 7 and the reference electrodes 8 and 9 are formed are superposed and placed on the heater, and the contact electrode 5 and the reference electrode 8, After the contact electrode 6 and the reference electrode 9 are positioned so as to face each other, the heater is heated to about 400 ° C., +600 V is applied to the silicon wafer 1 and 0 V is applied to the glass substrate 4 to bond them by anodic bonding. Finally, dicing is performed to cut into individual chips to complete the production of the pressure switch.

As a result of a pressurization test of the pressure switch described above, the contact point 5 comes into contact with the reference electrode 8 on the glass substrate 4 at a pressurization of 1 kg / cm ² to establish electrical conduction, and further pressurizes. At 5 kg / cm ² , conduction between the contact 6 and the contact electrode 9 was confirmed, and two pressures could be detected by one diaphragm. In the present embodiment, the cavity 3 has a depth of 1 μm and the diaphragm 2 has a thickness of 25 μm, and pressures of 1 kg / cm ² and 2.5 kg / cm ² can be detected. However, the numerical values and other conditions are not limited thereto.

That is, there is no problem even if the thickness of the cavity 3 or the diaphragm 2 is changed according to the required pressure range. Further, although the case where the pressure to be detected is two has been described in the present embodiment, a larger number of pressures can be detected by increasing the number of the concave portions 7 and the contact electrodes of the glass substrate 4.

[0011]

[Effect of the device]

 Since the present invention can detect pressure in several stages with one diaphragm, a pressure switch of extremely small size can be provided.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a pressure switch of the present invention.

FIG. 2 is a plan view showing a pressure switch of the present invention.

FIG. 3 is a schematic sectional view of a conventional pressure switch.

[Explanation of symbols]

 1 Silicon Wafer 2 Diaphragm 3 Cavity 4 Glass Substrate 5, 6 Contact Electrode

Claims (2)

[Scope of utility model registration request] 1. A pressure-receiving diaphragm having a contact electrode formed thereon and a glass substrate having a reference electrode formed thereon, the pressure-receiving diaphragm and the glass substrate are bonded to each other with the electrodes facing each other. In a pressure switch that senses an electrical connection state by contact between the contact electrode and the reference electrode, a concave portion is formed in a part of the glass substrate, and the reference electrode is arranged in the concave portion so that a portion other than the concave portion is formed. A pressure switch characterized by being capable of contacting the contact electrode with a time lag between the arranged reference electrode and detecting pressure in several stages. 2. The pressure switch, wherein each contact of the contact electrode on the pressure receiving diaphragm is electrically independent.