JPH05242778A - Manufacture of semiconductor pressure switch - Google Patents

Abstract

PURPOSE:To improve the accuracy and reliability of a pressure switch together with its manufacture at a low cost. CONSTITUTION:A wiring electrode 3 is formed through a process of forming a recessed part 2 by etching and through the diffusion of boron across the inside and the outside of the recessed part 2. A contact electrode 6 and a bonding pad 8 are formed on the inside and the outside of the recessed part 2 respectively. A glass substrate 9 provided with a reference electrode 10 formed on its one face is prepared. After placing, on a heater 15, a silicon substrate, which got through the above machining process, the recessed part 2 of the silicon substrate and the reference electrode 10 formed on the glass substrate 9 are placed thereon in opposition to each other. A diaphagm 11 comprises the glass substrate 9 and the silicon substrate bonded to each other by heating the heater 15 and the recessedly formed face of the silicon substrate etched from the other face thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor pressure switch.

[0002]

2. Description of the Related Art A manufacturing process of a conventional semiconductor pressure switch will be described with reference to FIGS. First, the thickness is 525 μm,
A resist is applied to the N-type silicon substrate 1, exposed and developed, and patterning is performed so that the resist in the shape of the recess 2 is removed. After the patterning is completed, the silicon substrate 1 is put into a plasma etching apparatus, a mixed gas of CF ₄ and O ₂ is introduced, and a high frequency of about 70 W is applied to the silicon substrate 1.
Is etched to form a recess 2 having a depth of 3 μm (see FIG. 5).
(A), (b)). After forming the concave portion 2, a resist is applied, exposed and developed, and patterned so that the resist in the portion where the boron electrode 3 is formed is removed, and boron ion implantation is performed to form the boron electrode 3. (Fig. 5
(C), (d)).

After forming the boron electrode 3, an oxide film 4 is formed as an insulating film and patterned so that the oxide film 4 remains in the recess 2 (FIGS. 5E and 5F). Subsequently, the polycrystalline silicon 5 is deposited by LPCVD, and etching is performed with a mixed solution of hydrofluoric acid and nitric acid so that the polycrystalline silicon 5 remains in the portion where the contact electrode 6 is formed (FIGS. 5G and 5H). )).

Next, in order to form the contact electrode 6, the wiring electrode 7 and the bonding pad 8, the sputtering electrode A is used.
u and Cr are deposited and Au and Cr are etched to form the contact electrode 6, the wiring electrode 7 and the bonding pad 8 (FIGS. 5 (i) and 5 (j)). On the other hand, Au on the glass substrate 9
Cr is sputtered and patterned to form the reference electrode 10 (FIGS. 5 (k) and 5 (l)).

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 placed on the heater 15 (see FIG. 6).
(A)), The heater 15 is heated to about 400 ° C., 0 V is applied to the glass substrate 9 and about 500 V is applied to the silicon substrate 1 for 20 minutes to anodic bond the silicon substrate 1 and the glass substrate 9.
After the anodic bonding is completed, a silicon nitride film 12 is formed on the opposite side of the glass substrate 9 to form a diaphragm at 150 ° C.
The silicon nitride film 12 is patterned with phosphoric acid of FIG.
(B)).

Further, an alkali resistant coating agent is applied to the bonding pad 8 and immersed in a potassium hydroxide aqueous solution (KOH) at 90 ° C. for about 3.5 hours to form the diaphragm 11, and the silicon substrate 1 is etched by about 500 μm. Then, the diaphragm 11 having a thickness of 22 μm was formed, and the coating agent was peeled off to manufacture the pressure switch (FIG. 6C).

[0007]

However, when the contact point on the diaphragm and the electrode by diffusion of impurities such as boron are connected by a metal such as Au-Cr, the pressure can be detected for a while, but the diaphragm is in the atmosphere. Since it moves at any time according to the change in the pressure on the side, film peeling of the oxide film 4 and the like occurs and there is a problem in reliability. In addition, there is a problem in that there is a difference in the amount of deflection between a portion on the diaphragm where wiring is provided and a portion where no wiring is provided, the uniformity of the deflection of the diaphragm is poor, and as a result the accuracy is poor.

[0008]

In order to solve the above problems, the present invention provides an electrode by diffusion of impurities such as boron for electrical connection from the contact on the recess to the atmosphere side without using a metal electrode. It is designed to be wired by.

[0009]

[Operation] By manufacturing through the above steps,
Since the wiring on the diaphragm is not a metal, there is no risk of peeling of the film and the reliability is high. Further, since the deflection amount of the diaphragm is uniform, an accurate semiconductor pressure switch can be provided. Moreover, since the steps of forming and patterning the metal film are eliminated, the manufacturing can be performed at low cost.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of a semiconductor pressure switch according to the present invention will be described as an embodiment with reference to FIGS. First,
A resist is applied to the N-type silicon substrate 1 having a thickness of 525 μm, exposed and developed to perform patterning so that the resist having the shape of the recess 2 is removed. After patterning,
Put the silicon substrate 1 in the plasma etching device, and use CF
A mixed gas of ₄ and O ₂ is introduced, a high frequency of about 70 W is applied, and the silicon substrate 1 is etched to form a recess 2 having a depth of 3 μm.
Are formed (FIGS. 1A and 1B).

After forming the concave portion 2, a resist is applied, exposed and developed, and patterned so that the resist in the portion where the boron electrode 3 is formed is removed, and boron ions are implanted to form the boron electrode 3. (FIG. 1 (c),
(D)). Subsequently, Au and Cr are deposited by sputtering to form the contact electrode 6, and the contact electrode 6 is formed in the center of the recess.
Are positioned so that two bonding pads 8 are formed at the electrode lead-out portion of the boron electrode 3.
u and Cr are etched (FIGS. 1E and 1F). On the other hand, Au and Cr are sputtered on the glass substrate 9 and patterned to form the reference electrode 10 (FIG. 1 (g),
(H)).

Next, the reference electrode 10 of the glass substrate 9 is set so as to face the contact electrode 6 formed on the silicon substrate 1, and these are placed on the heater 15 so that the heater 1
5 is heated to about 400 ° C., 0 V is applied to the glass substrate 9 and about 500 V is applied to the silicon substrate 1 for 20 minutes to anodic bond the silicon substrate 1 and the glass substrate 9 (FIG. 2A). After the anodic bonding is completed, a silicon nitride film 12 is formed on the opposite side of the glass substrate 9 and the bonding portion of the silicon substrate 1, and the silicon nitride film 12 is patterned with phosphoric acid at 150 ° C. so as to have a diaphragm shape (see FIG. b)).

Further, an alkali resistant coating agent 16 is applied to the bonding pad 8 and immersed in a potassium hydroxide aqueous solution (KOH) at 90 ° C. for about 3.5 hours to etch the silicon substrate 1 by about 500 μm, and a diaphragm with a thickness of 22 μm. 11 was formed and the coating agent was peeled off to manufacture a switch (FIG. 2C). A plan view and a sectional view of this switch are shown in FIGS.

The manufactured semiconductor pressure switch was put in a pressure vessel and pressurized to confirm the conduction between the two bonding pads 8. As a result, the conduction could be confirmed at 2.0 kg / cm ² . Further, the pressure measurement was repeated 100 times to measure the variation in the conducted pressure, and all the pressures were ± 0.0
It was within 25 kg / cm ² . Further, even if the pressurization was performed 200,000 times, no breakage or the like occurred, and there was no change in the value of the conducting pressure.

As described above, according to the method of the present invention, a semiconductor pressure switch having high accuracy and high reliability such as durability can be manufactured.

[0016]

According to the present invention, the electrical connection from the contact on the concave portion to the atmosphere side is performed by the electrode by the diffusion of impurities such as boron, and since it is not a metal wiring, there is no risk of peeling of the electrode film. A highly reliable semiconductor pressure switch can be provided because it is highly reliable and the amount of deflection of the diaphragm is uniform. Moreover, since the steps of forming and patterning the metal film are eliminated, the manufacturing can be performed at low cost.

[Brief description of drawings]

FIG. 1 is a process drawing showing a manufacturing procedure of a semiconductor pressure switch of the present invention.

FIG. 2 is a process drawing showing a manufacturing procedure of the semiconductor pressure switch of the present invention.

FIG. 3 is a plan view of the semiconductor pressure switch of the present invention.

FIG. 4 is a sectional view of a semiconductor pressure switch of the present invention.

FIG. 5 is a process drawing showing a manufacturing procedure of a conventional semiconductor pressure switch.

FIG. 6 is a process diagram showing a manufacturing procedure of a conventional semiconductor pressure switch.

[Explanation of symbols]

 1 Silicon Substrate 2 Recess 3 Boron Electrode 6 Contact Electrode 9 Glass Substrate 10 Reference Electrode

Claims (1)

[Claims] 1. A step of forming a recess on one surface of a silicon substrate by etching, a step of diffusing impurities into the silicon substrate to form a wiring electrode over the inside and outside of the recess, and a wiring formed in the recess. A step of forming a contact electrode on the upper surface of the electrode and a bonding pad outside the recess of the wiring electrode, a step of preparing a glass substrate having a reference electrode formed on one side, and a silicon substrate that has undergone the processing step above the heater. The step of placing the concave portion of the silicon substrate and the reference electrode formed on the glass substrate so as to face each other, and the step of joining the glass substrate and the silicon substrate by heating the heater, A method of manufacturing a semiconductor pressure switch, comprising the steps of etching a surface of a silicon substrate on which a recess is formed from the other surface to form a diaphragm.