JP3093066B2 - Semiconductor acceleration sensor and method of manufacturing the same - Google Patents

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 sensing acceleration of an automobile, an aircraft, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, commercialization of a semiconductor acceleration sensor for sensing acceleration has been promoted in order to operate an airbag of a vehicle safety device. A conventional semiconductor acceleration sensor of this type is disclosed in Japanese Patent Application Laid-Open No. Hei 3-2535 (G01L).
1/18), and has a configuration shown in FIGS. 6 to 8.

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

Reference numeral 8 denotes four piezoresistors formed on the upper surface of the thin portion 7 on the upper surface of the chip 4 by diffusion, 9 denotes a protective film made of a silicon dioxide film formed on the upper surface of the chip 4 including the resistor 8, 10 Is an aluminum wiring connected to the resistor 8 and connected to the outside, 11 is a mass portion made of glass adhered to the lower surface of the mass support portion 6, and a gap 12 is provided between the lower surface of the mass portion 11 and the upper surface of the pedestal 1. Are formed. The pedestal 1
Regulates the displacement of the mass portion 11 to prevent the thin portion 7 from being damaged.

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

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

Next, a method for manufacturing a semiconductor acceleration sensor will be described with reference to FIG. Chip 4 shown in FIG. 8A
As shown in FIG. 8B, a rim glass plate 17 having a porous portion serving as the rim portion 3 and a mass glass piece 18 serving as the mass portion 11 are bonded to the sensor wafer 16 having the above-mentioned shape by an electrostatic pressure bonding technique. At the time of this electrostatic compression bonding, for example, in a 300 ° C. atmosphere, the sensor wafer 16, the rim glass plate 17 and the mass glass piece 18 are applied while a load of 100 g / cm ² is applied to the sensor wafer 16, the rim glass plate 17 and the mass glass piece 18. A voltage of 500 V is applied to the piece 18 for 10 minutes for adhesion.

Thereafter, as shown in FIG. 8C, the rim glass plate 17 and the pedestal wafer 19 serving as the pedestal 1 are bonded together by the electrostatic pressure bonding technique as described above. Next, as shown in FIG.
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, when the rim glass plate 17 and the pedestal wafer 19 are bonded by an electrostatic pressure bonding technique, the mass portion 11 and the pedestal 1 are connected to each other by a strong electric field. At the interface of
Oxygen ions in the glass move and combine with the 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. For this reason, there are problems that acceleration cannot be sensed, yield decreases, and productivity decreases.
SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor acceleration sensor and a method for manufacturing the same, which prevent the mass portion from being attached to the pedestal when the rim is attached to the pedestal and improve the productivity while keeping the above points in mind. .

[0010]

In order to solve the above-mentioned problems, a method for manufacturing a semiconductor acceleration sensor according to the present invention comprises a silicon sensor chip, a frame-shaped peripheral portion, a mass support portion located substantially at the center, and a mass support portion. After forming a thin-walled portion that supports the above, a mass portion made of glass is adhered to the lower surface of the mass support portion, and a rim portion is adhered to the peripheral portion, and an insulating film is formed on the upper surface of the silicon pedestal facing the mass portion. electrostatic silicon pedestal on the lower surface of the rim portion to form a gap between the lower surface of the mass portion
Crimp and silicon film based on strong electric field of electrostatic crimping with insulating film
Hinders the movement of silicon atoms on the silicon pedestal,
Prevents adhesion due to formation of silicon dioxide film with mass
The silicon pedestal is bonded to the lower surface of the rim while stopping .

Further, the semiconductor acceleration sensor of the present invention has a silicon sensor chip having a frame-shaped peripheral portion, a mass support portion located substantially at the center, a thin portion supporting the support portion, and a lower surface of the support portion. Glass mass, rim bonded to lower surface of peripheral edge, and electrostatic crimping to lower surface of rim
A silicon base bonded by a gap formed between the lower surface of the pedestal and the mass portion is formed on the upper surface of the pedestal facing the mass portion of the gap, Siri to suppress strong electric field of the static voltage wear
The formation of a silicon dioxide film between the pedestal and the mass
And a concavo-convex layer for preventing adhesion . Further, in the semiconductor acceleration sensor according to the present invention, the uneven layer is formed on the lower surface of the mass portion facing the pedestal.

[0012]

In the method of manufacturing the semiconductor acceleration sensor according to the present invention, the insulating film is formed on the upper surface of the silicon pedestal facing the mass portion, and then a gap is formed between the insulating film and the lower surface of the mass portion. The pedestal is bonded to the lower surface of the rim by electrostatic compression, so that the movement of silicon atoms on the pedestal is hindered by the insulating film, and the silicon dioxide film is prevented from being formed at the interface between the pedestal and the mass. And the mass portion can be prevented from being bonded, and the insulating film can be formed by using the existing semiconductor manufacturing technology, so that an inexpensive semiconductor acceleration sensor can be obtained.
Productivity is improved.

Further, the semiconductor acceleration sensor of the present invention has a
The top of the pedestal facing the base or the mass facing the pedestal
On the underside ofSuppressing the strong electric field of electrostatic crimping
Prevents adhesion due to formation of silicon dioxide film
DoBecause an uneven layer was formed,Electrostatic crimpingGeneration of strong electric field
The silicon dioxide film is suppressed at the interface between the pedestal and the mass.
Formation is prevented, and the base and the mass are bondedToPreventionWhile still
The pedestal is adhered to the lower surface of the rim by voltage application.
You.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described with reference to FIGS. 6 to 8 indicate the same or corresponding elements, and 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, then Li
The base 3 and the pedestal 1 are electrostatically pressed and the pedestal is
1 by forming a silicon dioxide film between
The point is that the rim 3 and the pedestal 1 are bonded while preventing the bonding . Next, a method for manufacturing the insulating film 21 will be described.

2A to 2D show a conventional example of FIGS.
D is the same as the manufacturing process, and 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 on a portion facing the mass portion 11 by a photolithography technique. Thereafter, as shown in FIG. 2G, the 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, FIGS. 1 and 2
1 denote the same or corresponding elements, and the difference from FIG. 1 is that the uneven layer 23 is replaced with the insulating film 21 in FIG.
Is formed so as to suppress the generation of a strong electric field of electrostatic pressure bonding when the rim portion 3 and the pedestal 1 are bonded, and to prevent the mass portion 11 from being bonded to the pedestal 1. The manufacturing method of No. 23 will be described.

4A to 4D are the same manufacturing steps as those of FIGS. 2A to 2D. As shown in FIG. 4E, the unnecessary oxide film 15 is removed, and then a predetermined pattern is formed as shown in FIG. 4F. Sandblasting is performed by sandblasting particles 25 using a metal mask 24 having the metal mask 24, and an uneven layer 23 of 3 μm or more is formed on the pedestal 1 facing the mass portion 11.

Next, still another embodiment will be described with reference to FIG. 3, the same reference numerals as those in FIGS. 1 and 3 denote the same or corresponding parts, and the difference from FIG. 3 is that the uneven layer 23 is provided on the lower surface of the mass portion 11 facing the pedestal 1 instead of the uneven layer 23 in FIG. 26 is formed, and the lower surface of the mass portion 11 facing the pedestal 1 is sandblasted to form an uneven layer 26 of 3 μm or more in the same manner as described above.

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

[0020]

Since the present invention is configured as described above, the following effects can be obtained. According to the method for manufacturing a semiconductor acceleration sensor of the present invention, after forming an insulating film 21 on the upper surface of the silicon pedestal 1 facing the mass portion 11, a gap 12 is formed between the insulating film 21 and the lower surface of the mass portion 11 to form the rim portion 3. The pedestal 1 is adhered to the lower surface by electrostatic crimping, so the insulating film
The 21 inhibits the movement of the silicon atoms of the base 1 by a strong electric field of the electrostatic voltage wear, to prevent the formation of <br/> silicon dioxide film at the interface between the base 1 and the mass portion 11 pedestal 1 and the mass portion 11
Can be prevented, and productivity can be improved.

Further, since the semiconductor acceleration sensor of the present invention, the formation of the uneven layer 23 and 26 on the lower surface of the mass portion 11 facing the top or the base 1 of the base 1 facing the mass portion 11, the concavo-convex layer 23 and 26 Thus, the generation of a strong electric field due to electrostatic pressure bonding can be suppressed, and the pedestal 1 and the mass 11 are formed by forming a silicon dioxide film at the interface between the pedestal 1 and the mass 11.
To the base of the rim by electrostatic crimping while preventing
The seat can be formed by bonding .

[Brief description of the drawings]

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

FIGS. 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 each a process view of a part of FIG.

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

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

7A to 7E are partial process diagrams of a part of FIG. 6;

8A to 8D are process diagrams of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pedestal 3 Rim part 4 Silicon sensor chip 5 Peripheral part 6 Mass support part 7 Thin part 11 Mass part 12 Air gap 21 Insulating film 23 Uneven layer 26 Uneven layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Kunimi 5-4-71 Higashi, Hanyu-shi, Saitama Prefecture Akebono Brake Industry Co., Ltd. No. In Akebono Brake Central Technical Research Institute, Inc. (56) References JP-A-4-89577 (JP, A) JP-A-4-216469 (JP, A) JP-A-4-21872 (JP, U) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) G01P 15/02 G01P 15/08 G01L 15/12 H01L 29/84

Claims (3)

(57) [Claims] 1. A frame-shaped peripheral portion on a silicon sensor chip,
Forming a mass support portion located substantially at the center, a thin portion supporting the mass support portion, bonding a mass portion made of glass to a lower surface of the mass support portion, and bonding a rim portion to the peripheral edge portion; After an insulating film is formed 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, and the silicon pedestal is electrostatically pressed on the lower surface of the rim portion.
And before the insulating film is based on the strong electric field of the electrostatic pressure bonding.
Hinders the movement of silicon atoms on the silicon pedestal,
The shape of the silicon dioxide film between the recon pedestal and the mass
The rim is attached to the lower surface while preventing adhesion due to
A method of manufacturing a semiconductor acceleration sensor, comprising bonding a pedestal . 2. A silicon sensor chip having a frame-shaped peripheral portion, a mass support portion located substantially at the center, a thin portion supporting the support portion, and a mass portion made of glass adhered to a lower surface of the support portion. A rim portion bonded to the lower surface of the peripheral edge portion, a silicon pedestal bonded to the lower surface of the rim portion by electrostatic compression, a gap formed between the pedestal and the lower surface of the mass portion, It is formed on the upper surface of the pedestal facing the mass portion of the air gap, and suppresses the strong electric field of the electrostatic pressure bonding to form the seal.
The shape of the silicon dioxide film between the recon pedestal and the mass
A semiconductor acceleration sensor comprising a concave-convex layer for preventing adhesion due to formation . 3. A silicon sensor chip having a frame-shaped peripheral portion, a mass support portion located substantially at the center, a thin portion supporting the support portion, and a mass portion made of glass adhered to a lower surface of the support portion. A rim portion bonded to the lower surface of the peripheral portion by electrostatic compression, a silicon pedestal adhered to the lower surface of the rim portion, and a pedestal formed between the pedestal and the lower surface of the mass portion. Formed on the lower surface of the mass portion facing the pedestal of the gap, and suppressing the strong electric field of the electrostatic pressure bonding to form the seal.
The shape of the silicon dioxide film between the recon pedestal and the mass
A semiconductor acceleration sensor comprising a concave-convex layer for preventing adhesion due to formation .