JPH05203519A - Manufacture of pressure sensor - Google Patents

Abstract

PURPOSE:To prevent the intrusion of etching liquid without adverse effects on already formed elements by forming a groove in a glass substrate facing a pad on a silicon substrate, performing anode bonding, removing the glass at the groove part from the side of the glass substrate after etching, and expos ing an electrode pad. CONSTITUTION:The part of the reference chamber of a silicon substrate 1 is etched. With SiO2 as a mask, a diffusing layer 5, which is to become an electrode, is formed on the surface of a diaphragm 4. A junction member film 6 and an aluminum pad 11 are sequentially formed as the thin films. Meanwhile, an aluminum thin film is formed on a glass substrate 3. An aluminum electrode 7 is formed by photoetching. Thus, a groove 12 is formed. Then, the substrate 1 and the substrate 3 are bonded by anode bonding. Anisotropic etching for forming the diaphragm 4 is performed. Then, the groove is further formed from both sides of the part of the groove 12, and the electrode pad 11 is exposed. Thereafter, electric checking and compressing test are conducted. Dicing is performed into the final shape of the sensor. During the manufacturing, liquid intrusion and adverse effects on the elements do not occur, and the intended characteristics are obtained.

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 pressure sensor which detects changes in gas, liquid and pressure as displacements of a diaphragm and converts the changes into electric signals for output.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 2 (a) and 2 (b), a method of manufacturing a diaphragm type semiconductor pressure sensor has shown that a reference chamber surface of a silicon substrate 1 is protected by an etching resistant film and then etched. After that, etching is performed in a state of being bonded to the glass substrate 3 to form a hole for attaching a lead wire, or
Alternatively, after the glass substrate 3 having the holes is joined, the holes are filled with the epoxy resin 9 or the like and then the etching is performed.

For example, "Small absolute pressure sensor with new feedthrough structure" (Electronics Theory C, Vol. 110, No. 4)
No. pp. 255-262, 1990) discloses such a production method.

[0004]

However, conventionally, when it is attempted to protect by a protective film which is resistant to etching, there is a possibility that the elements already formed on the diaphragm 4 (for example, electrodes, bonding prevention film, etc.) are adversely affected. However, there is a problem that process conditions are restricted. Also, the method of closing the mounting hole of the lead wire 10 with the conductive epoxy resin 9 is
At the time of dicing, which is the final step, there are problems that the lead wire 10 becomes an obstacle and it is difficult to perform an electrical test in a wafer state. Further, when the filling with the conductive epoxy resin 9 is insufficient, there is a problem that the etching solution enters between the glass substrate 3 and the silicon substrate 1.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems, so that the intrusion of an etching solution can be surely prevented without adversely affecting already formed elements, and wiring can be formed after etching or dicing. Is to

[0006]

In order to solve the above problems, according to the present invention, a portion of the glass substrate 3 which does not come into contact with the pad of the silicon substrate 1 is formed and anodically bonded. After the etching in this state, the glass in the grooved portion is removed from the glass substrate 3 side with a dicing saw to expose the electrode pad.

[0007]

According to the method of manufacturing the pressure sensor as described above,
The etching solution does not enter between the glass substrate and the silicon substrate during etching, and the lead wire can be attached after dicing.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 1 shows a process of a method for manufacturing a pressure sensor according to the present invention. First, the double-sided polished silicon wafer 1 having an n-type crystal orientation (100) is etched in a portion to be the reference chamber 8 by using a normal photolithography technique. Next, a diffusion layer 5 of boron serving as an electrode is formed on the surface of the diaphragm 4 by using SiO ₂ as a mask, and a bonding prevention film 6 and an aluminum pad 11 are sequentially formed by using ordinary thin film formation and photoetching techniques. To do.

On the other hand, an aluminum thin film is formed on the glass substrate 3 having a thickness of 300 μm by vacuum deposition, and an aluminum electrode 7 is formed by photoetching. Next, a groove 12 having a depth of 100 μm is formed in a pattern as shown in FIG. 3 by using a dicing saw or etching with the aluminum electrode 7 as a reference. In this case, the depth of the groove 12 may be a rough level, but if the depth is 150 μm or more, the glass wafer may be damaged in a later step, and if the depth is 30 μm or less, the dicing for exposing the pad 11 is performed. May damage the pad. Next, the glass substrate and the silicon substrate are bonded by anodic bonding. The conditions in this case are a temperature of 400 ° C., a DC applied voltage of 400 V, and an atmosphere of nitrogen gas. This is anisotropically etched for forming the diaphragm 4 with a 35 wt% KOH aqueous solution.

Next, using a dicing saw, the groove portion of the glass that was initially inserted is re-grooved from the glass surface side to expose the electrode pad. After that, an electrical check and a pressure test are performed, and dicing into the final sensor shape is performed. In the manufacturing process as described above, desired characteristics were obtained without any liquid intrusion during etching and with no influence on the previously formed element. (2) In the manufacturing method of the above (1), the glass substrate is grooved by using a material formed by etching with a mixed solution of nitric acid and hydrofluoric acid using chromium and gold as mask materials. Similarly, the etching liquid did not enter, and the desired value was obtained for the characteristics.

[0011]

As described above, according to the present invention, a glass substrate is first grooved, and after being bonded to a silicon substrate, a diaphragm is formed by etching, and the glass in the grooved portion is removed by dicing, Since the manufacturing method is to expose the electrode pad, there is no hole for the lead wire in the glass substrate during etching, the etching solution does not enter the boundary between the glass surface and the silicon surface, and finally the electrode Since the pad is exposed, the wire bonder can be used, normal dicing, and electrical check can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for manufacturing a pressure sensor of the present invention.

FIG. 2 is an explanatory diagram of a conventional method of manufacturing a pressure sensor.

FIG. 3 is an explanatory diagram of a groove pattern on a glass substrate.

[Explanation of Codes] 1 Silicon substrate 2 SiNx film 3 Glass substrate 4 Diaphragm 5 Diffusion layer 6 Bonding prevention film 7 Aluminum electrode 8 Reference chamber 9 Conductive epoxy resin 10 Lead wire 11 Aluminum pad 12 Groove on glass substrate

Claims (1)

[Claims] 1. A semiconductor pressure sensor in which a portion of a silicon substrate has a so-called diaphragm structure in a thin state, a pressure change is detected as a deflection amount of the diaphragm, and the deflection amount is converted into an electric signal in an electrode pad on the silicon substrate. Grooving processing is performed on the glass substrate facing the part of, and the grooving processing side of the glass substrate is bonded to the etching side of the silicon wafer that has been subjected to etching for forming the reference chamber, and then bonded to form a diaphragm. A method of manufacturing a pressure sensor, which comprises performing etching and cutting the groove portion from the glass side.