JPH03150435A - Manufacture of relative pressure sensor - Google Patents

Abstract

PURPOSE:To eliminate damaging in the process of a product and to improve the yield by using an Ni thin film as an electrode which faces an Si electrode on a diaphragm, and heating and reducing an Si substrate and glass after anode joining. CONSTITUTION:An Si wafer 1 which is 200 mum thick is oxidized to form an SiO2 film 2, which is etched so that the Si surface appears only at the cavity part and IC mounding part of the diaphragm. A 'Borofilm(R)' 3 is formed by coating, an etching stop layer 4 is formed, and SiO2 5 for contact prevention is left. Then 'Pyrex(R)' glass 6 which is 200 mum thick is pierced by discharge working and after an Ni film 7 is formed, an electrode pattern is formed by photolithography. On an Si cover 8 for which outside air is admitted, SiO2 9 is formed and SiNx 10 is formed on one surface. Then the Si wafer 1 and Si cover 8 are anode-joined with both surfaces of the glass 6, heating reduction processing is carried out, the Si 1 is etched to form the diaphragm 11. Consequently, the sensor is manufactured at high yield.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a water pressure gauge, a barometer, and a small volumetric relative pressure gauge that is attached to the tip of a catheter and inserted into the body to measure the pressure at each site. The present invention relates to a method of manufacturing a pressure sensor.

[Summary of the invention]

The present invention relates to a method for manufacturing a pressure sensor for a capacitance meter that senses changes in pressure by changes in capacitance generated in a pair of electrodes formed on a diaphragm and a substrate. After using anodic bonding to bond glass and St, reduction treatment is performed with 12+02 forming gas, and the area where the IC is mounted is formed in the same manner as the diaphragm to prevent liquid from entering the area until dicing. To prevent. Furthermore, in cutting,
This method of manufacturing a relative pressure sensor is characterized in that after dicing is performed to a depth shallower than the thickness of the glass, a YAG:Nd laser is irradiated from the groove side of the dicing to cut the Si cover on the back side.

[Conventional technology]

Conventionally, a pressure sensor called a semiconductor sensor is generally a pressure sensor that uses piezo resistance.

In conventional manufacturing methods, it is common practice to leave only the diaphragm portion by etching, to use AlCr or the like as the electrode, and to perform cutting only by dicing.

In recent years, capacitive pressure sensors have been proposed with the aim of improving sensitivity and reducing power consumption. However, there is still no example of practical use in a small size, and it is not widespread. Because,
This is because a small relative pressure capacity type pressure sensor cannot be manufactured by applying the conventional semiconductor sensor manufacturing method.

[Problem to be solved by the invention]

When a capacitance type relative pressure type pressure sensor is manufactured using the general manufacturing method for semiconductor pressure sensors as described above, the etching solution enters into the cavity of the diaphragm during etching, and the electrodes previously formed on the glass plate are damaged. It had the disadvantage of damaging the Furthermore, when a metal that is easily oxidized, such as Cr, is used as an electrode, the metal surface is oxidized during anodic bonding, resulting in poor bonding with the IC. Furthermore, if canting is performed only with a dicing saw, water and dirt may enter the cavity of the diaphragm during dicing, resulting in malfunction.

[Means to solve the problem]

In order to solve the above problems, in the present invention, a Si cover is left on the IC mounting part in the same process as forming the diaphragm, and a portion of the cover is removed after cutting. In addition, it was decided to use Ni as an electrode on glass and to perform a reduction treatment after anodic bonding. Furthermore, during dicing, a cut is made to about half the thickness of the glass, and then a YAG:Nd laser is irradiated from the back side (the opposite side of the diaphragm) to cut the Si cover on the back side, thereby preventing moisture from entering the cavity of the diaphragm. I tried not to enter.

[Effect]

By using the manufacturing method as described above, it is possible to manufacture a capacitive relative pressure sensor with a high yield without damage to the electrodes or malfunction of the diaphragm.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a process diagram of the manufacturing method according to the present invention.

(al n (100) 20077111 thickness Si
A wet oxide film 2 is formed on the wafer 1, photolithography is performed so that only the Si surface of the diaphragm cavity portion and the IC mounting portion is exposed, and 5i02 is etched.

(b) Etch the Si using a 35wt% KOH solution (temperature 80°C). This forms a gear between the diaphragm and the Ni electrode. After this, 5iOz
remove. fc) Polo film (Type manufactured by Emulsitone Co.) as a high concentration diffusion source of boron.
B) Spin code 3 onto the previously etched surface. td) Heat treated at 1190℃ for 64 hours to a depth of about 15
A P etching stop layer 4 of .mu.m is formed. After te+ oxidation, SiO□5 as a bonding prevention film is left only on the surface etched in step tb+ by photolithography. (
fl A hole is made in the Pyrex glass 6 of 200 μm by electrolytic discharge machining, a Ni film 7 is deposited, and then a pad for connecting the electrode pattern, Ic, and a lead is formed by photolithography. As the Si cover 8 for introducing outside air, 5i029 is formed on a 200μ Si wafer (gl n (100) by thermal oxidation, and then SiN Then, it is etched with a hydrazine solution (90° C.) to form grooves.Then, the SiO□9 used for patterning is removed.

The Sil made in the process up to te+ and the glass 6 made in the ffl process are joined by (hl anodic bonding. (Temperature 380°C Voltage on the glass side -600V) anodic bonding with fJ)
The diaphragm 11 is formed by etching Si with a 35 wt% KOH solution (80°C). Next (use a dicing saw to cut a groove halfway through the thickness of the glass,
81 on the klIc mounting part is removed by pressing down on the boundary and breaking it. After reducing Nj7 again,
+1lYAG+Nd laser 13 is irradiated from the groove side in the glass to cut the Si cover. After mounting an IC as a CF converter 14 on this and further attaching a lead 15, the catheter was attached to the tip of the catheter as shown in FIG.

In the sensor manufactured by the method described above, there was no intrusion of foreign matter into the diaphragm cavity, and there was no damage to the electrodes during enching. Furthermore, there were no conduction defects due to the oxide film.

Note that FIG. 3 shows a configuration diagram of the characteristic evaluation system. In the figure, 17 is a chamber for pressurizing or depressurizing, 18 is a pressure monitor, 19 is a thermocontroller for keeping the temperature constant, and 20 is an I MHz capacitance meter. The data obtained are shown in FIG. In addition, in the case where the manufacturing method according to the present invention was not carried out, electrode damage, conduction failure, foreign matter contamination, etc. occurred, and none of them functioned as a sensor.

〔Effect of the invention〕

By implementing the manufacturing method according to the present invention, a capacitive relative pressure sensor can be manufactured without being damaged during the process.

[Brief explanation of the drawing]

Fig. 1 is a T diagram of the manufacturing method according to the present invention, Fig. 2 is a sectional view when attached to the tip of a catheter, Fig. 3 is a configuration diagram of a characteristic evaluation system, and Fig. 4 is a diagram of the sensor manufactured according to the present invention. It is a relationship diagram between pressure and capacity.・・Si wafer ・・5i02 ・・borofilm・・etch stop layer・・5i02 6 ・ ・ 7 ・ ・ 8 ・ ・ 9 ・ ・ 10 ・ ・ 11 ・ ・ 12 ・ 13 ・ ・ 14 ・ ・ 15 ・ 16・ ・ 17 ・ 18 ・ 19 ・ 20 ・ 21 ・ 22 ・ 23 ・ 24 -F converter/lead/SUS pipe pressure chamber/pressure monitor/thermo controller/IMHz capacity meter/DC power supply/■meter/rubber tube resin 0 Button diagram 5 16 4 Taku diagram 2 Prologue diagram 3rd layer

Claims (1)

[Claims] In a so-called capacitive pressure sensor that senses pressure by the capacitance generated between an electrode formed on a diaphragm that deforms in response to pressure changes and an electrode facing the electrode, the following is provided. A method for manufacturing a characterized relative pressure pressure sensor. (1) Ni as the electrode opposite to the electrode on the diaphragm
Using a thin film, after anodic bonding of the Si substrate and glass, H_
A method for manufacturing a pressure sensor, which comprises reducing the pressure sensor while heating it to 300°C or higher in a forming gas of 2 and N_2. (2) A method for manufacturing a relative pressure sensor, characterized in that the diaphragm is formed by wet etching, and at the same time, a pad portion on which an IC is mounted is left in the same manner as the diaphragm. (3) When cutting wafers manufactured in a batch process, the wafers are cut shallower than the thickness of the glass using a dicing saw.
Next, a method for manufacturing a relative pressure sensor, characterized in that a YAG:Nd laser is irradiated from the groove side generated by dicing to cut the Si cover on the back side through the glass.