JPH05126844A - Semiconductor acceleration sensor and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To remove adverse effect of burr-like matter of an insulated protective film after an etching in an acceleration sensor in which a groove is cut inward in a substrate by performing a specified etching with an insulation film as etching protection film after the formation of the insulation film on the surface of a semiconductor substrate to form a cantilever type strain gauge. CONSTITUTION:A groove 4 is cut inward in a substrate 1 by a specified etching to form a cantilever type strain gauge 3. Thereafter, an etching mask thin film part is removed at least on the surface of a corner of the strain gauge 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cantilever type semiconductor acceleration sensor.

[0002]

2. Description of the Related Art A cantilever type sensor for acceleration detection is provided with a strain gauge that exerts a strain resistance effect on the surface of a cantilever-supported strain-measuring element, so that fluctuations in the strain-generating body can be electrically controlled by a predetermined circuit. It is detected as a change in static resistance, the stress applied to the strain generating element is measured based on the change in the resistance value, and the acceleration which is the non-measurement target is detected. As the strain gauge, a metal foil or a single crystal that is adhered on a strain-generating body, or a semiconductor thin film formed on the surface of the strain-generating body is known. The present invention relates to a sensor in which the wafer itself is a strain body.

This semiconductor acceleration sensor is disclosed in Japanese Unexamined Patent Publication No. 61-
As disclosed in Japanese Patent No. 97572, after forming an insulating coating on the surface of a substrate, a predetermined etching is performed using this insulating coating as an etching protection film, and a groove is bored inside the substrate to form a cantilever strain element. Is formed, and a strain gauge, a lead portion, and an insulating protective film are formed on the base portion of the strain-generating body in a predetermined manner to produce the product.

[0004]

By the way, in the semiconductor acceleration sensor described above, the portion protected by the protective mask is not necessarily corroded by the etching solution during etching when forming the strain element, and the substrate is not dissolved. If it advances, the side surface of the melting hole, that is, the lower surface of the protective mask is also attacked by the etching solution. As a result, as shown in FIG. 3, the protective mask c is projected in a burr shape at the groove b portion around the flexure element a.

This burr-like thin film, particularly when it remains at the corners of the strain-generating body, breaks easily during the subsequent manufacturing process or when it is used as a sensor, and easily falls off from the strain-generating body. There is a sufficient possibility of fitting in the groove around the strained body, and if it fits in the groove, the reliability as a sensor may decrease. Therefore, the present invention proposes a semiconductor acceleration sensor in which the burr-like thin film is removed.

[0006]

A semiconductor acceleration sensor according to the present invention is a cantilever in which a strain gauge is formed on a predetermined semiconductor substrate by means of a thin film forming means, and a groove is formed inside the substrate by etching. An acceleration sensor in which a strain-generating element of the type is formed is characterized in that at least a thin film portion on the corner surface of the strain-generating element is removed.

Further, in the method for manufacturing the semiconductor acceleration sensor, after forming an insulating film on the surface of the semiconductor substrate, a groove is bored inward of the substrate by a predetermined etching using this insulating film as an etching protective film, and a cantilever type is formed. In the manufacturing method of forming the strain gauge, the lead portion, and the insulating protective film on the base of the strain generating body after forming the strain generating body, in the step after forming the strain generating body, at least the corner surface of the strain generating body is formed. It is characterized in that the etching mask thin film portion is removed.

[0008]

When the etching mask thin film portion of the surface of the strain generating body is removed after the formation of the strain generating body by the etching process and at least including the corner portions of the strain generating body and other than the formation portion of the strain gauge, the strain generating body is removed. The thin film portion of the etching mask does not remain like burrs at the corners of.

[0009]

EXAMPLES Next, examples of the present invention will be described. Figure 1
Shows the semiconductor acceleration sensor of the embodiment of the present invention, and FIG. 2 shows the manufacturing process thereof. An embodiment of the present invention will be described along with its manufacturing process. An insulating film (SiO ₂ ) is formed on the front and back surfaces of a semiconductor substrate (amorphous silicon wafer) 1.
2 is formed and the insulating film 2 is used as a protective film for Si etching. Therefore, a part of the protective film 2 is removed by a conventional photoetching method in correspondence with the groove 4 forming the strain element 3. The substrate 1 is subjected to an etching treatment (both front and back, and in particular, not only the groove 4 but also the back surface of the base of the strain generating body 3 is removed) to form the strain generating body 3. Next, a polysilicon resistor to be the strain gauge 5 is formed on the upper surface of the base of the strain-generating body 3 by a conventional thin-film manufacturing means, and the surface of the substrate is further covered with a protective film (SiO ₂ ) 6, and then the strain-generating body 3 is formed. The front part and the entire back surface of the substrate 1 are removed, the lead connecting portion (contact hole) 7 of the strain gauge 5 is opened, and the lead electrode 8 is provided.

Thus, the sensor is used as an acceleration detecting device by accommodating it in an appropriate base case with pins protruding and connecting the lead electrode portion 8 to the pin via a lead wire. Therefore, in the acceleration sensor according to the present invention, there is no possibility that a part of the etching protection film may fall off and be fitted into the groove 4 around the strain-generating body 3 during the manufacturing process and the above-mentioned use.

The present invention is not limited to the above-mentioned embodiment, and the substrate 1, the insulating film 2, the strain gauge, etc. may be made of any material as long as they exhibit desired performance.
Further, the removal of the protective film may be carried out at any step after the formation of the strain generating body, such as particularly at the same time as the formation of the lead connecting portion (contact hole) 7.

[0012]

As described above, according to the present invention, a strain gauge is formed on a semiconductor substrate by a thin film forming means, and a groove is formed in the substrate by etching to form a cantilever type flexure element. In the acceleration sensor, a semiconductor acceleration sensor in which at least the thin film portion on the corner surface of the strain element is removed, and in the method for manufacturing the semiconductor acceleration sensor,
The problem of partial removal of the etching protection film due to the formation of the strain body is solved, and the reliability of the semiconductor acceleration sensor is improved.

[Brief description of drawings]

FIG. 1 is an overall perspective view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the same manufacturing process.

FIG. 3 is an overall perspective view of a conventional sensor.

[Explanation of symbols]

 1 substrate 2, 6 insulating film (protective film) 3 strain element 4 groove 5 strain gauge 7 lead connection part (contact hole) 8 lead electrode part

Claims (2)

[Claims] 1. An acceleration sensor in which a strain gauge is formed on a predetermined semiconductor substrate by a thin film forming means, and a cantilever type strain-generating body is formed by digging a groove in the substrate by etching. A semiconductor acceleration sensor, wherein at least a thin film portion on a corner surface of the strain body is removed. 2. After forming an insulating coating on the surface of a semiconductor substrate, a groove is bored inward of the substrate by a predetermined etching using this insulating coating as an etching protective film to form a cantilever type flexure element. In a method of manufacturing a semiconductor sensor in which a strain gauge, a lead portion, and an insulating protective film are formed on the base of the strain generating body, at least in the step after forming the strain generating body, at least the etching mask thin film portion on the corner surface of the strain generating body is formed. A method for manufacturing a semiconductor acceleration sensor, characterized by being removed.