JPH06167510A - Semiconductor acceleration sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To achieve higher productivity by preventing adhesion between the top surface of an opposed base and the undersurface of a square part. CONSTITUTION:A frame-shaped periphery part 5, a square support part 6 located almost at the center and a thin part 7 supporting the mass support part 6 are formed at a silicon sensor chip 4 and a square part 11 comprising glass is bonded on the undersurface of the square support part 6 while a rim part 3 is bonded on the periphery 5. An insulation film 21 is formed on the top surface of a silicon base 1 facing the square part 11, then, a gap 21 is formed between the film and the under-surface of the square part 11 and the base 1 is bonded on the undersurface of the rim part 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor acceleration sensor for detecting the acceleration of an automobile, an aircraft or the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in order to operate an airbag of a safety device for an automobile, a semiconductor acceleration sensor for detecting an acceleration has been commercialized. A conventional semiconductor acceleration sensor of this type is disclosed in Japanese Patent Application Laid-Open No. 3-25535 (G01L).
1/18), and has the configuration shown in FIGS. 6 to 8.

In FIG. 6, 1 is a silicon pedestal, 2 is a gap portion formed by etching in the central portion of the upper surface of the pedestal 1, and 3 is glass that is adhered to the peripheral portion of the upper surface of the pedestal 1 by electrostatic pressure bonding. A rim portion, 4 is a silicon sensor chip made of an n-type silicon substrate adhered to the upper surface of the rim portion 5, 5 is a frame-shaped peripheral portion of the chip 4, 6 is a mass support portion located substantially in the center of the chip 4, Reference numeral 7 denotes a diaphragm-shaped thin portion formed by etching between the peripheral portion 5 and the mass support portion 6.

Reference numeral 8 denotes four piezoresistors formed by diffusion on the upper surface of the thin portion 7 on the upper surface of the chip 1, 9 indicates a protective film made of a silicon dioxide film formed on the upper surface of the chip 4 including the resistor 8. Is an aluminum wiring connected to the resistor 8 and is connected to the outside, and 11 is a mass portion made of glass adhered to the lower surface of the mass supporting portion 6, and a space 12 is provided between the lower surface of the mass portion 11 and the upper surface of the pedestal 1. Are formed. In addition, pedestal 1
Regulates the displacement of the mass portion 11 to prevent the thin portion 7 from being damaged.

In the semiconductor acceleration sensor configured as described above, when acceleration is applied, the mass portion 11 is displaced in that direction, the thin portion 7 is deformed by this displacement, the resistance value of the piezoresistor 8 is changed, and the acceleration Can be detected.

Next, a method of manufacturing the pedestal 1 will be described with reference to FIG. An oxide film 15 is formed on the one-sided mirror surface 14 of the silicon wafer 13 shown in FIG. 7A as shown in FIG. 7B, and as shown in FIG. 7C, the oxide film 15 in the portion to be the gap 2 is etched by photolithography and etching. And removed to form a predetermined pattern. Next, as shown in FIG. 7D, a gap portion 2 having a depth of 3 μm is formed by a predetermined etching solution, for example, an etching solution in which hydrofluoric acid and nitric acid are mixed, and thereafter, as shown in FIG. Remove 15.

Next, a method of manufacturing the semiconductor acceleration sensor will be described with reference to FIG. Chip 4 shown in FIG. 8A
As shown in FIG. 8B, a porous glass plate 17 for rim which becomes the rim part 3 and a mass glass piece 18 which becomes the mass part 11 are adhered to the sensor wafer 16 having the above. During this electrostatic pressure bonding, for example, in the atmosphere of 300 ° C., the sensor wafer 16, the rim glass plate 17 and the mass glass piece 18 are applied with a load of 100 g / cm ^{2 on} the sensor wafer 16, the rim glass plate 17 and the mass glass piece 18. 500V is applied to the piece 18 for 10 minutes to bond them.

After that, as shown in FIG. 8C, the rim glass plate 17 and the pedestal wafer 19 to be the pedestal 1 are bonded by the electrostatic pressure bonding technique as described above. Next, as shown in FIG. 8D, the multi-layer structure wafer 20 thus formed is
It is cut using a dicing saw and separated into semiconductor acceleration sensor pellets.

[0009]

In the conventional method of manufacturing a semiconductor acceleration sensor described above, when the glass plate for rim 17 and the pedestal wafer 19 are bonded by the electrostatic pressure bonding technique, the mass portion 11 and the pedestal 1 are attached to each other by a strong electric field. At the interface of
Oxygen ions in the glass move and bond with silicon of the pedestal 1, silicon dioxide is formed between the mass portion 11 and the pedestal 1, and the mass portion 11 is fixed. Therefore, there are problems that the acceleration cannot be detected, the yield is deteriorated, and the productivity is lowered.
The present invention has been made in consideration of the above points, and an object of the present invention is to provide a semiconductor acceleration sensor capable of preventing the mass portion and the pedestal from being bonded to each other when the rim portion and the pedestal are bonded to each other and improving the productivity, and a manufacturing method thereof. .

[0010]

In order to solve the above-mentioned problems, a method for manufacturing a semiconductor acceleration sensor according to the present invention is directed to a silicon sensor chip in which a frame-shaped peripheral portion, a mass support portion located substantially at the center, and a mass support portion. After forming a thin part that supports the glass support, a mass part made of glass is adhered to the lower surface of the mass support part, a rim part is adhered to the peripheral part, and an insulating film is formed on the upper surface of the silicon pedestal facing the mass part. A space is formed between the lower surface of the mass portion and the lower surface of the rim portion so that the silicon pedestal is bonded.

In the semiconductor acceleration sensor of the present invention, a silicon sensor chip having a frame-shaped peripheral edge portion, a mass support portion located substantially in the center, and a thin portion supporting the support portion is adhered to the lower surface of the support portion. A mass part made of glass, a rim part bonded to the lower surface of the peripheral part, a silicon pedestal bonded to the lower surface of the rim part, a void formed between the pedestal and the lower surface of the mass part, and a mass of the void. And a concavo-convex layer formed on the upper surface of the pedestal facing the section. Further, in the semiconductor acceleration sensor of the present invention, the uneven layer is formed on the lower surface of the mass portion facing the pedestal.

[0012]

According to the method of manufacturing the semiconductor acceleration sensor of the present invention having the above-described structure, the insulating film is formed on the upper surface of the silicon pedestal facing the mass portion, and then the gap is formed between the insulating film and the lower surface of the mass portion. Since the pedestal is adhered to the lower surface of the rim portion by the insulating film, the movement of silicon atoms on the pedestal is alienated, the formation of the silicon dioxide film at the interface between the pedestal and the mass portion is prevented, and the pedestal and the mass portion are prevented from forming. Adhesion can be prevented, and the insulating film can be formed by using an existing semiconductor manufacturing technique, so that an inexpensive semiconductor acceleration sensor can be obtained and productivity is improved.

Further, in the semiconductor acceleration sensor of the present invention, since the uneven layer is formed on the upper surface of the pedestal facing the mass portion or on the lower surface of the mass portion facing the pedestal, generation of a strong electric field is suppressed, and the pedestal and the mass portion are separated from each other. The formation of the silicon dioxide film is prevented at the interface of the, and the adhesion between the pedestal and the mass portion can be prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described with reference to FIGS. 6 to 8 indicate the same or corresponding ones. The difference from FIG. 6 is that an insulating film such as a silicon dioxide film or a silicon nitride film is formed on the upper surface of the pedestal 1 facing the mass portion 11. 21 is formed, and then the rim portion 3 and the pedestal 1 are bonded together. Next, a method of manufacturing the insulating film 21 will be described.

The manufacturing process of FIGS. 2A to 2D is the same as that of the conventional example shown in FIGS.
The manufacturing process is the same as that of D. As shown in FIG.
A CVD oxide film, that is, an insulating film 21 is formed on the entire surface by the D technique, and then, as shown in FIG. 2F, a predetermined resist pattern 22 is formed by the photolithography technique on the portion facing the mass portion 11. Then, as shown in FIG. 2G, unnecessary oxide film 15, insulating film 21, and resist pattern layer 22 are removed by etching.

Next, another embodiment will be described with reference to FIGS. In these figures, FIG. 1 and FIG.
1 indicates the same or corresponding ones, and the difference from FIG. 1 is that instead of the insulating film 21 of FIG.
Is formed, and when the rim portion 3 and the pedestal 1 are bonded together, generation of a strong electric field is suppressed to prevent the mass portion 11 and the pedestal 1 from being bonded together. Next, the method for manufacturing the uneven layer 23 is described. Will be described.

4A to 4D are the same manufacturing steps as FIGS. 2A to 2D, the unnecessary oxide film 15 is removed as shown in FIG. 4E, and then a predetermined pattern is formed as shown in FIG. 4F. Sandblasting is performed with sandblast particles 25 using the metal mask 24 that is provided to form a concavo-convex layer 23 of 3 μm or more on the pedestal 1 facing the mass portion 11.

Next, another embodiment will be described with reference to FIG. In the figure, the same reference numerals as those in FIGS. 1 and 3 indicate the same or corresponding ones, and the difference from FIG. 3 is that the uneven layer is provided on the lower surface of the mass portion 11 facing the pedestal 1 instead of the uneven layer 23 of FIG. 26 is formed, and the uneven surface layer 26 having a thickness of 3 μm or more is formed on the lower surface of the mass portion 11 facing the pedestal 1 by sandblasting in the same manner as described above.

In the above embodiment, the pedestal 1 having the gap 2 formed at the center of the upper surface has been described as an example.
The pedestal 1 may have no gap portion 2 and the pedestal 1 may be flat. Further, the uneven layers 23 and 26 may be polished with an abrasive.

[0020]

Since the present invention is configured as described above, it has the following effects. According to the method for manufacturing a semiconductor acceleration sensor of the present invention, after the insulating film 21 is formed on the upper surface of the silicon pedestal 1 facing the mass portion 11, the void 12 is formed between the insulating film 21 and the lower surface of the mass portion 11 to form the rim portion 3. Since the pedestal 1 is adhered to the lower surface, the movement of silicon atoms on the pedestal 1 can be isolated and the pedestal 1 and the mass portion 11 can be separated.
It is possible to prevent the formation of the silicon dioxide film at the interface with the, and to prevent the pedestal 1 and the mass portion 11 from adhering to each other, thereby improving the productivity.

In the semiconductor acceleration sensor of the present invention, since the uneven layers 23 and 26 are formed on the upper surface of the pedestal 1 facing the mass portion 11 or the lower surface of the mass portion 11 facing the pedestal 1, generation of a strong electric field is suppressed. Therefore, the silicon dioxide film can be formed at the interface between the pedestal 1 and the mass portion 11, and the adhesion between the pedestal 1 and the mass portion 11 can be prevented.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of an embodiment of the present invention.

2A to 2G are process diagrams of a part of FIG.

FIG. 3 is a partially cutaway perspective view of another embodiment of the present invention.

4A to 4G are process diagrams of a part of FIG.

FIG. 5 is a partially cutaway perspective view of still another embodiment of the present invention.

FIG. 6 is a partially cutaway perspective view of a conventional example.

7A to 7E are process diagrams of a part of FIG.

8A to 8D are process diagrams of FIG.

[Explanation of symbols]

 1 pedestal 3 rim portion 4 silicon sensor chip 5 peripheral portion 6 mass support portion 7 thin portion 11 mass portion 12 void 21 insulating film 23 uneven layer 26 uneven layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kei Kunimi 5-4-71 Higashi, Hanyu City, Saitama Prefecture, Akebono Break Industrial Co., Ltd. (72) Inventor Tadashi Kobayashi 5-471 Higashi, Hanyu City, Saitama Prefecture Akebono Brake Central Technology Research Institute Co., Ltd.

Claims (3)

[Claims] 1. A silicon sensor chip having a frame-shaped peripheral portion,
A mass supporting portion located substantially in the center and a thin portion supporting the mass supporting portion are formed, and a mass portion made of glass is bonded to the lower surface of the mass supporting portion, and a rim portion is bonded to the peripheral portion, After forming an insulating film on the upper surface of the silicon pedestal facing the mass portion, a gap is formed between the silicon pedestal and the lower surface of the mass portion to bond the silicon pedestal to the lower surface of the rim portion. Sensor manufacturing method. 2. A silicon sensor chip having a frame-shaped peripheral portion, a mass support portion located substantially at the center, a thin wall portion supporting the support portion, and a mass portion made of glass adhered to the lower surface of the support portion. A rim portion adhered to the lower surface of the peripheral portion, a silicon pedestal adhered to the lower surface of the rim portion, a void formed between the pedestal and the lower surface of the mass portion, and the mass of the void. Acceleration sensor provided with an uneven layer formed on the upper surface of the pedestal facing the section. 3. A silicon sensor chip having a frame-shaped peripheral portion, a mass support portion located substantially in the center, a thin portion supporting the support portion, and a mass portion made of glass adhered to the lower surface of the support portion. A rim portion bonded to the lower surface of the peripheral portion, a silicon pedestal bonded to the lower surface of the rim portion, a void formed between the pedestal and the lower surface of the mass portion, and the pedestal of the void And a concavo-convex layer formed on the lower surface of the mass portion facing the semiconductor acceleration sensor.