JPH06242139A - Semiconductor acceleration sensor - Google Patents

Abstract

PURPOSE:To provide a semiconductor acceleration sensor which can prevent a hinge part from damage by an excessive stress, has high sensitivity, and is handled easily during the production. CONSTITUTION:In a semiconductor acceleration sensor, which is provided with a sensor chip 1 consisting of a mass part 2, a frame part 3, and a hinge part 4 and detects acceleration on the basis of a stress generated in the hinge part 4 when the mass part 2 is displaced according to the acceleration, a stopper 5, which increases the weight of the mass part 2, is fixed in the mass part 2 of the sensor chip 1, and at least one part of around the stopper 5 is faced to the frame part 3, and the interval T between the stopper 5 and the frame part 3 under the steady state is set so that the displacement quantity of the mass part 2 is the quantity by which target acceleration can be detected and the hinge part 4 is not damaged.

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 which calculates acceleration by detecting stress applied to a semiconductor.

[0002]

2. Description of the Related Art A conventional acceleration sensor will be described with reference to FIGS. 4 and 5. FIG. 4A is a top view showing a sensor chip 1 used in the acceleration sensor, and FIG. 4B is a sectional view taken along the line AA. The sensor chip 1 is configured by integrally connecting a central mass portion 2 and a frame-shaped frame portion 3 that surrounds the mass portion 2 with a hinge portion 4 that is extremely thin. A plurality of such sensor chips 1 are manufactured from one single crystal wafer by etching the silicon single crystal wafer, for example.

When acceleration is input to the sensor chip 1 in the direction of the arrow in FIG. 4B, the mass portion 2 is displaced with respect to the frame portion 3 as shown by the dotted line, and the hinge portion 4 is deformed accordingly. Then, since stress is generated in this portion, the magnitude of acceleration can be detected from the magnitude of this stress. Incidentally, since the signal extracting means for this detection is well known in the art, the description thereof will be omitted here. In this case, if an excessive acceleration is input, the hinge portion 4 may be largely displaced, and may be damaged in some cases.

To avoid this, conventionally, as shown in FIG. 5A, a stopper 5 having a U-shaped cross section is provided so as to straddle the mass portion 2 and the hinge portion 4, so that the sensor chip 1 is sandwiched from above and below. The end face is fixed to the frame portion 3 with an adhesive or the like. As a result, when an excessive acceleration is input, the mass portion 2 comes into contact with the stopper 5 to limit the further displacement, as shown in FIG. 5B, and prevents the hinge portion 4 from being damaged. Stopper 5 and mass part 2 shown in FIG. 5A
The gap t constituted by is capable of detecting the acceleration targeted by the displacement amount of the mass portion 2 and is held at a value at which the hinge portion 4 is not damaged.

[0005]

In order to increase the sensitivity of the semiconductor acceleration sensor in this structure, the mass part 2 is increased in size to increase its mass, or the hinge part 4 is formed to be thinner, longer and thinner. Good. However, in this configuration, the strength of the hinge portion 4 is reduced, and the hinge portion 4 is damaged by an impact or the like.
Has a problem that it is easily damaged. Further, when the hinge portion 4 is formed thinner, longer, and thinner in this way, the strength of the hinge portion 4 decreases as described above. Therefore, care must be taken in handling the sensor chip 1 even during the manufacturing of the semiconductor acceleration sensor. However, there is a problem that its manufacture becomes difficult. Therefore, there is a need for a sensor chip that is relatively easy to handle without breaking.

Further, it is important in terms of cost and production efficiency to take out a larger number of sensor chips 1 from one semiconductor wafer, and increasing the mass portion 2 in order to increase the sensitivity is not enough. There is a problem that the number of sensor chips 1 manufactured from one semiconductor wafer decreases. The present invention provides a semiconductor acceleration sensor that avoids the above problems.

[0007]

In order to solve the above-mentioned problems, the present invention has a sensor chip 1 composed of a mass portion 2, a frame portion 3 and a hinge portion 4, and the mass portion responds to acceleration. In a semiconductor acceleration sensor that detects acceleration by the stress generated in the hinge portion 4 when 2 is displaced, a stopper 5 for increasing the weight is fixed to the mass portion 2 of the sensor chip 1 and at least one of the periphery of the stopper 5 is fixed. The distance between the stopper 5 and the frame portion 3 in the steady state is such that the displacement amount of the mass portion 2 is a detectable amount of the target acceleration and the hinge portion 4 is damaged. It has been selected as a value that does not receive.

[0008]

In the present invention, since the stopper 5 is attached to the mass portion 2 of the sensor chip 1, the mass portion 2 increases in mass by the weight of the stopper 5, and the mass portion 2 is displaced even with a slight acceleration. Easier to do. Therefore, the sensitivity is improved as compared with the conventional semiconductor acceleration sensor shown in FIG. 5 without increasing the size of the mass portion 2 and without making the hinge portion 4 of the sensor chip 1 thin, long and thin. Of course, the stopper 5 also functions as a stopper, which is the original purpose.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a semiconductor acceleration sensor according to the present invention will be described with reference to FIGS. In the figure, those parts corresponding to those in FIGS. 4 and 5 are designated by the same reference numerals, and a description thereof will be omitted. In this embodiment, the sensor chip 1 has a structure similar to that described with reference to FIG. Further, the plate-shaped stopper 5 shown in FIG. 3 is made of a glass material, and a convex portion 5a is integrally formed in the central portion thereof. The convex portion 5a has a shape similar to that of the stopper body, and the center thereof coincides with the center of the stopper body.

A pair of stoppers 5 shown in FIG. 3 are used, and the upper surface of the convex portion 5a is adhered to the upper and lower portions of the mass portion 2 with an adhesive or the like. At this time, the center of the convex portion 5a and the mass portion 2
It is installed so that its center coincides with the center. The frame portion 3 is attached to the attachment base 7 by the attachment columns 6.
In this case, S between the lower stopper 5 and the mounting base 7 in the figure is selected to be larger than T described above (S> T).

When the lengths of the respective parts of the stopper 5 shown in FIG. 3 and the lengths of the respective parts of the sensor chip 1 shown in FIG. 4 are selected as the values shown, these values are set as follows.
In this case, the gap T formed between the stopper 5 and the frame portion 3 is a value at which the displacement amount of the mass portion 2 can detect the target acceleration and the hinge portion 4 is not damaged. Is held in.

(A) x ₃ > x ₁ (b) y ₃ > y ₁ (c) x ₄ <x ₂ (d) y ₄ <y ₂ However, only one of (a) and (b) is satisfied. It should be done.

According to the semiconductor acceleration sensor having this structure, when an excessive acceleration is input, the stopper 5 is brought into contact with the frame portion 3 of the sensor chip 1 to restrict further displacement, as shown in FIG. Therefore, it is possible to avoid the occurrence of excessive stress in the hinge portion 4. When an excessive stress is input in the direction opposite to the direction of the arrow in the figure, the stopper 5 on the lower side is in contact with the frame portion 3 to limit further displacement. Therefore, it is possible to prevent the hinge portion 4 from being damaged by an excessive input.

Further, since the stopper 5 made of glass or the like is attached to the mass portion 2, the mass of the mass portion 2 is increased accordingly, and the stopper 5 is not fixed to the mass portion 2. Compared to the case, the mass portion 2 is likely to be displaced with respect to the same acceleration, so that the sensitivity is increased as compared with the conventional semiconductor acceleration sensor.

[0015]

According to the present invention described above, it is not necessary to form the hinge portion of the sensor chip thinner, longer, and thinner than in the conventional case, and therefore, it is possible to avoid damage during the manufacturing process. Further, there is an effect that the mass can be increased and the sensitivity can be improved without enlarging the mass part itself. Further, there is an effect that the number of sensor chips obtained from one semiconductor wafer is not reduced. Of course, the stopper can avoid damaging the hinge portion due to excessive stress.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a semiconductor acceleration sensor according to the present invention.

FIG. 2 is a sectional view showing a displacement state of the semiconductor acceleration sensor shown in FIG.

FIG. 3A is a perspective view showing an example of a stopper usable in the present invention, B is a top view thereof, and C is a side view thereof.

FIG. 4A is a plan view showing an example of a sensor chip that can be used for a semiconductor acceleration sensor, and B is a sectional view taken along the line AA.

5A is a cross-sectional view showing an example of a conventional semiconductor acceleration sensor, and B is a cross-sectional view showing a displaced state thereof.

Claims (1)

[Claims] 1. A sensor chip comprising a mass part, a frame part surrounding the mass part, and a hinge part connecting the mass part and the mass chip part, wherein the mass part is displaced in response to an acceleration and a stress is generated in the hinge part. In a semiconductor acceleration sensor that detects acceleration, a stopper that increases the weight of the sensor chip is fixed to the mass portion of the sensor chip, and at least a part of the periphery of the stopper faces the frame portion. The semiconductor acceleration sensor is characterized in that the distance to the portion is set to a value such that the amount of displacement of the mass portion can detect the target acceleration and the hinge portion is not damaged.