JPH0594933U - Semiconductor pressure switch - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To reduce the resistance when the switch is turned on under pressure. A silicon substrate 1 having a pressure receiving diaphragm and a concave portion 2 and a glass substrate 9 are bonded to each other to shield the concave portion 2 from the atmosphere to form a gap, and a contact electrode 6 on the diaphragm formed inside the gap. And a reference electrode 10 on a glass substrate, the pressure switch for operating the switch unit by distorting the diaphragm by the pressure from the atmosphere side, the switch unit and the signal from the switch unit. A signal output circuit section 12 for receiving and controlling energization is formed on the silicon substrate. When the switch section is ON, the signal output circuit 12 is energized, and when it is OFF, the signal output circuit 12 is not energized.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a structure of a semiconductor pressure switch for reducing resistance.

[0002]

[Prior Art]

 A conventional semiconductor pressure switch will be described with reference to FIG. 4 (plan view) and FIG. 5 (cross-sectional view). Reference numeral 1 is an N-type silicon substrate, 2 is a recessed portion obtained by etching the silicon substrate 1 by about 3 μm by a plasma etching apparatus, and a diaphragm 11 having a thickness of about 20 μm is formed on the side opposite to the recessed portion by etching ing. 3 is a boron electrode diffused by boron ion implantation. An oxide film 4 is formed as an underlying insulating film of a wiring electrode on the concave portion 2, and a convex portion 5 of polycrystalline silicon formed by LPCVD is formed on the oxide film 4, and the convex portion 5 is formed. A contact electrode 6 of Au, Cr having a thickness of about 20 μm formed by a spatter is formed on the upper surface and connected to the boron electrode 3. 7 and 8 are Al bonding pads.

On one of the glass substrates 9 is a reference electrode 10 of Au or Cr formed by sputtering. The glass substrate 9 and the silicon substrate 1 on which the reference electrode 10 is formed are set so that the contact electrode 6 and the reference electrode 10 face each other, and the inside of the recess 2 and the atmosphere side are hermetically sealed and bonded by anodic bonding. is there. This conventional semiconductor pressure switch is put in a pressure vessel and pressurized to about 2 kg / cm2, the contact electrode 6 on the diaphragm 11 and the reference electrode 10 make contact, and the resistance value of the bonding pads 7 and 8 is about 800 Ω. It was

[0004]

[Problems to be solved by the device]

 However, although conventional semiconductor pressure switches can detect pressure for the time being, the resistance of the two bonds is the sum of the resistance values of the boron electrode, contact electrode, reference electrode, etc., so there is the problem that the resistance when the switch is on is high. there were.

[0005]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention has a switching function that includes a MOS transistor or the like that switches on and off depending on a signal from the switch, in addition to a switch for detecting pressure. The signal output circuit section is formed on the same silicon substrate.

[0006]

[Action]

 Since the output of the signal output circuit that has a switching function with a very low resistance value can be detected, a semiconductor pressure switch with a low resistance value when the switch is on can be manufactured. In addition, since necessary parts such as MOS transistors can be formed on the same silicon substrate, there is no need for labor and the size can be reduced.

[0007]

【Example】

 The semiconductor pressure switch of the present invention will be described with reference to FIG. 1 (plan view) and FIG. 2 (cross-sectional view). Reference numeral 1 is an N-type silicon substrate having a thickness of 525 μm and an outer diameter size of 2.5 × 2.0 mm, and 2 is a recess etched by about 3 μm by a plasma etching apparatus. Anisotropy is opposite to the recess 2. A thin diaphragm 11 having a thickness of about 20 μm formed by etching is formed, and the diaphragm 11 is distorted by the size of the recess 2 due to a change in pressure. Reference numerals 3 and 13 denote boron electrodes diffused by boron ion implantation. An oxide film 4 is formed as a base insulating film of the wiring electrode on the concave portion 2, and a convex portion 5 of polycrystalline silicon formed by LPCVD is 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 5 and 7 and 8 are Al bonding pads. Reference numeral 12 denotes a signal output circuit in which a MOS transistor 14 and a resistor 15 are formed. In order to further reduce the resistance value, the bonding pads 7 and 8 and the signal output circuit 12 are arranged at a short distance of 30 μm in this embodiment. .

On the other glass substrate 9, there is a reference electrode 10 of Au or Cr formed by sputtering. The glass substrate 9 and the silicon substrate 1 on which the reference electrode 10 is formed are set so that the contact electrode 6 and the reference electrode 10 face each other, and the inside of the recess 2 and the atmosphere side are hermetically sealed and bonded by anodic bonding. is there. Next, one embodiment of the use of the signal output circuit 12 and the present invention will be described with reference to FIG. 3 (circuit diagram). The signal output circuit is a circuit in which a MOS transistor and a resistor 15 of 1 MΩ are integrated. The gate of the MOS transistor 14 is connected to the contact electrode 6 on the diaphragm 11, and the source and drain are connected to bondings 7 and 8, respectively. It is connected. When pressure is applied and the diaphragm 11 is distorted and the contact electrode 6 and the reference electrode 10 come into contact with each other and the switch portion is turned on, that is, when a voltage is applied to the gate, a current flows from the source to the drain. .

The semiconductor pressure switch was placed in a pressure vessel, and the resistance value between the bonding pads 7 and 8 was measured. When the resistance value reached 2.0 kg / cm 2, the resistance of about 100 MΩ became 3 Ω. Thus, the conventional resistance of 800Ω becomes 3Ω, and the effect of the present invention is remarkable. Although the N-type silicon substrate is used in the present invention, a P-type silicon substrate may be used. Further, although the signal output circuit uses the MOS transistor, another switching element may be used, and a resistor of 1 MΩ is used, but another resistance value may be used depending on the conditions.

[0010]

[Effect of the device]

 Since this invention can detect the output of the signal output circuit having a switching function with a very small resistance value, a semiconductor pressure switch with a small resistance value when the switch is on can be manufactured. In addition, since a necessary component such as a MOS transistor is formed on the same silicon substrate, a small semiconductor pressure switch can be manufactured.

[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 circuit diagram of an embodiment of the present invention.

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

FIG. 5 is a sectional view of a conventional semiconductor pressure switch.

[Explanation of symbols]

 1 Silicon Substrate 2 Recess 3 Boron Electrode 7 and 8 Bonding Pad 9 Glass Substrate 10 Reference Electrode 12 Signal Output Circuit 14 MOS Transistor 15 Resistor

Claims (1)

[Scope of utility model registration request] 1. A glass substrate and a silicon substrate having a pressure-receiving diaphragm and a recess are bonded to each other to shield the recess from the atmosphere to form a gap, and a contact electrode on the diaphragm formed inside the gap and a glass substrate. In a pressure switch that has a switch part composed of the upper reference electrode and operates the switch part by distorting the diaphragm by the pressure from the atmosphere side, the switch part and a signal from this switch part are received to conduct electricity. MOS to control
A semiconductor pressure switch characterized in that a signal output circuit section having a transistor element or the like is formed on the silicon substrate, and the signal output circuit is energized when the switch section is ON, and the signal output circuit is not energized when the switch section is OFF. .