JP3171970B2 - Force / acceleration detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force / acceleration detecting device,
In particular, the present invention relates to a device for detecting an applied force or acceleration based on a change in resistance value of a resistance element formed on a semiconductor substrate.

[0002]

2. Description of the Related Art In recent years, devices for detecting physical quantities such as force, acceleration, and magnetism using a resistive element formed on a semiconductor substrate have been developed and put to practical use. For example, International Publication No. WO88 / 08522 based on the Patent Cooperation Treaty discloses that a plurality of resistance elements are formed by diffusing impurities into predetermined positions on a silicon substrate, and based on a change in the resistance value of these resistance elements, An apparatus for detecting force, acceleration, and magnetism of each axial direction component in an XYZ three-dimensional coordinate system is disclosed. In Japanese Patent Application Laid-Open Nos. 3-202778 and 4-84725, an annular groove is formed in a silicon substrate, and a resistance element formed above the annular groove is used to reduce the multiaxial component of acceleration. An apparatus for detecting is disclosed. Further, Japanese Patent Application Laid-Open No. 4-81630 discloses a manufacturing method suitable for mass production of such an acceleration detecting device.

A feature of these detecting devices is that a flexible portion thinner than other portions is formed by digging an annular groove in the lower surface of the semiconductor substrate, and a resistance element is formed in the flexible portion. When a force is applied to the semiconductor substrate, the flexible portion is bent, and the resistance element is mechanically deformed. The semiconductor resistance element has the property of the piezoresistance effect in which the resistance value changes due to such mechanical deformation. Therefore, by detecting a change in the resistance value of the resistance element, the direction and magnitude of the applied force can be detected. If a weight is added to the semiconductor substrate, the acceleration acting on the weight can be detected as a force. If a magnetic material is added instead of the weight, the magnetism acting on the magnetic material can be detected as a force. can do.

[0004]

When the above-described detection device is manufactured, an annular groove (in the present specification, the term "annular" is not limited to an annular shape, but a rectangular or other special annular shape). Digging) is required. This annular groove is desirably circular. This is because the annular groove forming portion becomes a flexible portion as it is and plays an important role of causing mechanical deformation. Therefore, in order to perform even and uniform stress distribution, a circular annular groove is ideal. It is. However, it is very difficult to form a circular annular groove on a semiconductor substrate. For mass production, physical cutting is inappropriate. Therefore, a chemical etching process is performed, but in order to make the groove circular, isotropic etching must be performed, and advanced technology is required for controlling the depth of the groove. A method of performing dry etching is also conceivable, but the time required for the etching process is long, resulting in a problem that productivity is reduced.

[0005] On the other hand, if anisotropic etching is performed, processing can be performed relatively easily in a short time, which is suitable for mass production. However, there is a problem that an annular groove cannot be obtained by anisotropic etching. For example, when anisotropic etching using an etching solution such as KOH, hydrazine, or EPW (ethylenediamine pyrocatechol water) is performed on the (110) plane of a silicon substrate having a relatively large piezoresistance coefficient, an octagonal shape is obtained. Is formed. Moreover, it is not a regular octagon but a slightly distorted octagonal annular groove. As described above, when the groove is not annular, an interference phenomenon occurs in which the detected value of each axial component is affected by the other axis component, and it becomes impossible to obtain an independent accurate detected value for each axis. . In order to eliminate such an interference phenomenon, for example, Japanese Patent Application Laid-Open No.
In the publication, a special signal processing circuit is disclosed,
If such a signal processing circuit is used, the cost of the device will increase accordingly.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a force / acceleration detecting device which can be manufactured at low cost by anisotropic etching and which can perform accurate detection without causing interference with other axes. Aim.

[0007]

[Means for Solving the Problems]

(1) The first invention of the present application is to form a flexible portion having flexibility by digging an annular groove on one surface of a semiconductor substrate, and to form a piezoresistive effect on the flexible portion on the other surface of the semiconductor substrate. Force / acceleration detection for detecting a predetermined detection axial component of the force or acceleration acting to cause the flexible portion to bend based on a change in the resistance value of the resistance element. In the apparatus, a polygonal annular groove is formed by using an anisotropic etching method, an arrangement axis is defined at a position shifted by a predetermined angle with respect to a predetermined detection axis, and on this arrangement axis, and The resistance element is arranged in the direction along the axis, and the predetermined angle is set so that the detection sensitivity with respect to the predetermined detection axis direction component is maximized.

(2) The second invention of the present application is the detection apparatus according to the first invention, wherein a silicon substrate is used as a semiconductor substrate, and an annular groove is dug in a (110) plane of the substrate to form a predetermined groove. The arrangement axis is defined at a position shifted by a predetermined angle from the detection axis in the <001> direction.

(3) The third invention of the present application is the detection device according to the second invention described above, wherein a plane in which the resistance element is arranged is:
An X axis is defined in a direction at 45 ° to the <001> direction, and a Y axis is defined in a direction orthogonal to the X axis. Further, a predetermined angle is set in a direction in which the X axis approaches the <001> direction. Defining a shifted V axis and a W axis shifted by a predetermined angle in a direction in which the Y axis approaches the <001> direction,
The configuration is such that the X-axis direction component is detected by a resistance element arranged on the V axis, and the Y-axis direction component is detected by a resistance element arranged on the W axis.

(4) According to a fourth aspect of the present invention, a flexible portion having flexibility is formed by digging an annular groove on one surface of a semiconductor substrate, and the flexible portion is formed on the other surface of the semiconductor substrate. A resistive element having a piezoresistive effect is provided, and a force or acceleration that acts to cause bending of the flexible portion in a predetermined detection axial direction component is detected based on a change in the resistance value of the resistive element. In the acceleration detection device, a polygonal annular groove is formed by using an anisotropic etching method, and the resistance element is arranged at a predetermined angle on a predetermined detection axis while being inclined, and in a predetermined detection axis direction. The predetermined angle is set so that the detection sensitivity for the component is maximized.

(5) The fifth invention of the present application is the detecting device according to the fourth invention, wherein a silicon substrate is used as a semiconductor substrate, and an annular groove is dug in the (110) plane of the substrate to perform detection. The resistance element is arranged on the axis in a direction inclined at a predetermined angle toward the <001> direction.

(6) The sixth invention of the present application is the detection device according to the fifth invention described above, wherein, in the plane on which the resistance element is arranged,
The X-axis is defined in a direction at 45 ° to the <001> direction, and the Y-axis is defined in a direction orthogonal to the X-axis, and the X-axis is inclined by a predetermined angle toward the <001> direction. The detection of the X-axis direction component is performed by the resistance element arranged in the direction, and the detection of the Y-axis direction component is performed by the resistance element arranged in the direction inclined by a predetermined angle toward the <001> direction on the Y axis. It is composed.

[0013]

[Function] When an X-axis and a Y-axis orthogonal to each other are defined on a semiconductor substrate, and the respective axial components of force / acceleration acting on the substrate are detected, conventionally, the X-axis component is defined on the X-axis. It has been thought that it is necessary to detect using a resistance element arranged along the X axis, and to detect a component in the Y axis direction using a resistance element arranged along the Y axis on the Y axis. . Indeed, in the case where the flexible portion is formed by the annular groove, by arranging the resistance element based on such a conventional concept, a detection result with almost sufficient accuracy can be obtained. However, in the case where the flexible portion is formed by irregularly shaped grooves formed by anisotropic etching, if the resistive element is arranged in the conventional manner, interference with other axes will occur.

The inventor of the present application has discovered the fact that this multi-axis interference can be suppressed by shifting the arrangement axis of the resistance element with respect to the detection axis, and has confirmed this fact by experiments. More specifically, an octagonal annular groove is formed by anisotropic etching on the lower surface of the substrate having the (110) plane of single crystal silicon as a main surface, and <001> is formed on the upper surface of the substrate.
When an X axis is defined in a direction at 45 ° to the direction and a Y axis is defined in a direction orthogonal to the X axis, a resistance element for detecting each axial direction component is provided on each axis. It was confirmed that an ideal output without interference with other axes could be obtained by arranging it slightly in the <001> direction instead of arranging it along the axis.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. First, the conventional force with an annular groove /
The structure and operation of the acceleration detection device will be briefly described. 1 and 2 are a cross-sectional view and a top view of the conventional device. A cross section of the device shown in FIG. 2 taken along a cutting line AA corresponds to FIG. The semiconductor substrate 10 is a single-crystal silicon substrate cut into a square, and an annular groove is dug in the lower surface. Here, a portion around the semiconductor substrate 10 is a fixing portion 11, a portion which is thinner and more flexible by an annular groove than the other portion has flexibility, and a central portion is an action portion 13. I will call it. When the fixed portion 11 is fixed to the detected position and a predetermined force is applied to the action point P of the action portion 13, the flexible portion 12 is bent by this force. In this device, the bending thus generated is detected by a plurality of resistance elements formed on the upper surface of the flexible portion 12. If a weight is added to the action point P,
The acceleration acting on the weight can be detected as the force acting on the point of action P.

Now, as shown in FIG. 2, an X-axis and a Y-axis are defined on the upper surface of the semiconductor substrate 10 at right angles above the action point P, and pass through the action point P and are perpendicular to both XY axes. The Z-axis is defined in an appropriate direction (upper direction perpendicular to the paper surface in FIG. 2). That is, the upper surface of the semiconductor substrate 10 is a surface included in the XY plane. When such a definition is made, in this device, the force applied to the point of action P is
It is possible to detect each axial direction component in the YZ three-dimensional coordinate system. Specifically, in order to detect the component in the X-axis direction, four resistance elements Rx1 to Rx1 are arranged on the X-axis along the X-axis.
Rx4 is formed, and four resistance elements Ry1 to Ry1 are formed on the Y axis along the Y axis in order to perform detection on the Y axis direction component.
Ry4 is formed, and four resistance elements Rz1 to Rz4 are formed on the cutting line AA in the drawing along the cutting line in order to detect the component in the Z-axis direction. However, four resistance elements R for detecting the Z-axis direction component are used.
z1 to Rz4 do not necessarily need to be arranged at this position, and may be arranged near the X axis along the X axis, or may be arranged near the Y axis along the Y axis.

Each of these resistance elements is actually formed as a layer in which an impurity is diffused at a predetermined position on a silicon substrate, and has a piezoresistance effect that the electrical resistance changes due to mechanical deformation. Each of the resistance elements is formed on the flexible portion 12, and when the flexible portion 12 bends due to the force applied to the action point P, a mechanical deformation occurs. Mechanical deformation that contributes to detection includes deformation in the direction of extension and deformation in the direction of contraction, and the polarity of the change in electrical resistance is determined based on which of the deformations. Therefore, FIG.
By configuring the bridge circuit as shown in (1), it is possible to detect each axial component of the force applied to the point of action P.
That is, with respect to the X-axis direction component, the resistance elements Rx1 to Rx1
If Rx4 is assembled in a bridge circuit as shown in FIG. 3A and a predetermined voltage is applied from a power supply 30, the output voltage Vx of the potentiometer 31 can be detected. As for the Y-axis direction component, the resistance elements Ry1 to Ry4 are shown in FIG.
When a predetermined voltage is applied from the power supply 30 to the bridge circuit shown in FIG. 1, the output voltage Vy of the potentiometer 32 can be detected. Further, with respect to the component in the Z-axis direction, the resistance elements Rz1 to Rz4 are assembled into a bridge circuit as shown in FIG. 3C, and when a predetermined voltage is applied from the power supply 30, it is detected as the output voltage Vz of the potentiometer 33. be able to. For details of this detection principle, refer to the above-mentioned publication.

In the conventional force / acceleration detecting device described above, since the annular groove is formed, if the resistance elements are arranged as shown in FIG. 2, there is almost no interference between the axial components. An accurate detection value can be obtained. However,
As described above, in order to dig an annular groove in a single-crystal semiconductor substrate, it is necessary to perform isotropic etching or dry etching, which requires an advanced etching technique or takes a long etching processing time. Therefore, it is not possible to manufacture a large number of detection devices at low cost. An object of the present invention is to provide a low-cost force / acceleration detection device suitable for mass production by forming an annular groove by performing anisotropic etching on a semiconductor substrate.

FIG. 4 is a top view of a silicon substrate 20 used in the force / acceleration detecting device according to the present invention. Usually, when a silicon substrate is used for a force / acceleration detecting device, a substrate having a (110) plane as a main surface is used. This is because, as shown in FIG. 5, the piezoresistance coefficient relating to the (110) plane is larger than that of the other planes, thereby enabling high-sensitivity detection. (110) of this silicon substrate 20
When the surface is subjected to anisotropic etching using an etching solution such as KOH, hydrazine, EPW (ethylenediamine / pyrocatechol / water), an octagonal annular groove is formed as shown by a broken line in FIG. Is formed. This octagon is not a regular octagon, and the side in the <001> direction shown is in the <-110> direction (because of the restriction of the electronic application, a bar cannot be written on the number, so it is written before the number)
It becomes a distorted shape longer than the side. By forming such an octagonal annular groove, similarly to the conventional detection device, a fixed portion 21 is formed around the periphery, a flexible portion 22 is formed at the portion of the annular groove, and an action portion 23 is formed at the center. , The flexible portion 22 is bent. Here, similarly to the conventional device shown in FIG. 2, an X axis and a Y axis are defined, and X
The resistance elements Rx1 to Rx4 are arranged on the axis, and the resistance elements Rx
By arranging the resistance elements Rz1 to Rz4 on the y1 to Ry4 and the resistance elements Rz1 to Rz4 on the <−110> direction, it is possible to obtain each axial component of the force applied to the point P by the circuit shown in FIG. Referring to the piezoresistive coefficient graph shown in FIG. 5, it can be seen that each of the above-described resistance elements is arranged in a direction in which the detection sensitivity is relatively high.

However, in the detection device as shown in FIG. 4, interference occurs with other axes, and accurate detection cannot be performed. Specifically, in the detection device shown in FIG. 4, the positive direction of the X-axis is set to 0 °, and hereinafter, the positive direction of the Y-axis is set to 9 °.
If the angle is defined up to 360 ° counterclockwise so as to be 0 °, graphs as shown in FIGS. 6 and 7 are obtained. FIG. 6 is a graph showing the output voltage Vx of the potentiometer 31 shown in FIG. 3A, and FIG. 7 is a graph showing the output voltage Vy of the potentiometer 32 shown in FIG. In each graph, the horizontal axis indicates the angle 0 to 360 ° defined by the above-described method, and the output voltage actually appearing when a force is applied to the point P in the angular direction is drawn by a solid line. . All the graphs deviate from the ideal graphs shown by the broken lines, indicating that interference occurs between the X and Y axes. For example, when a force acts in the direction of 0 ° (positive direction of the X axis), the output Vx indicating the X axis direction component should be the maximum output, and the output Vy indicating the Y axis direction component should be zero. (This is the case for the ideal output shown by the dashed line). However, actually, in the direction of 0 °, the output Vx does not reach the maximum output,
y does not become zero. Therefore, even when a force acts only in the positive direction of the X axis, an erroneous output indicating a force component in the Y axis direction is obtained.

It is considered that the main cause of such interference with other axes is that the angle θ1 at which the direction in which the resistive element is arranged intersects with the edge of the annular groove is not a right angle. That is, in the conventional device as shown in FIG. 2, since the edge of the annular groove has a circumference, the angle formed by the resistance element arrangement direction is always a right angle. However, in the detection device shown in FIG. 4, the intersection angle θ1 does not become a right angle because the octagon is distorted. Note that no interference occurs between the Z-axis component and the X-axis or the Y-axis. This is probably because the distorted octagonal annular groove is symmetrical with respect to the Z axis.

The inventor of the present application actually made a prototype of a detection device having a configuration as shown in FIG.
Experiments were conducted in each direction of 360 °, and FIGS.
A graph as shown by a solid line in FIG. As a result, it has been found that the actual output shown by the solid line is shifted from the ideal output shown by the broken line by almost the same phase difference θ2 at any position on the horizontal axis. Then, it was demonstrated that the phase difference θ2 can be offset by slightly displacing the arrangement of the resistance elements with respect to the detection axis. That is, in the detection device shown in FIG.
Axis) and an arrangement axis (also an X axis) on which a resistance element for detecting a force component on the detection axis is arranged coincides. On the other hand, in the detection device according to the first embodiment of the present invention, as shown in FIG. 8, an arrangement axis V is defined at a position slightly shifted from the X axis which is a detection axis, and this arrangement axis V
The resistance elements Rx1 to Rx used for detecting the X-axis direction component
4 are arranged along the arrangement axis V, and similarly, the detection axis Y
An arrangement axis W is defined at a position slightly deviated from the axis, and a resistance element Ry1 used for detecting a component in the Y-axis direction is disposed on the arrangement axis W.
To Ry4 are arranged along the arrangement axis W. Where X
By changing the setting of the deviation angle θ3 between the V axis and the W axis with respect to the Y axis and the Y axis, the phase difference θ shown in FIGS.
2 will change. Therefore, a shift angle θ3 that satisfies the phase difference θ2 = 0 is obtained, and each resistor element is arranged on the V axis and the W axis defined based on the shift angle θ3. As a result, an ideal output as indicated by a broken line is obtained, and interference between the X and Y axes can be canceled.

No theoretical analysis has yet been made on the principle of canceling out interference by such a method. Therefore, even if the solid line graphs shown in FIGS. 6 and 7 are obtained by experiments, and the phase difference θ2 can be obtained from the graphs, the optimum shift angle θ3 for canceling out the phase difference θ2 is calculated. No guidance method has been found so far. However, as shown in FIG. 8, using the (110) plane of the silicon substrate, an X axis is defined in a direction at 45 ° to the <001> direction, and a Y axis is defined in a direction orthogonal to the X axis. The X-axis is <00
The V axis may be defined at a position shifted by a predetermined angle θ3 in a direction approaching the 1> direction, and the W axis may be defined at a position shifted by a predetermined angle θ3 in a direction approaching the <001> direction. It could be confirmed. Therefore, when mass production is performed, prototypes in which the deviation angle θ3 is set to various values are prepared, and when a force is applied in the X-axis or Y-axis direction, a prototype (in which the detection sensitivity for each axial component is maximized) In other words, the deviation angle θ is obtained by a method of finding a prototype which can obtain an ideal output as shown by a broken line in FIGS.
What is necessary is just to determine the optimal setting value as 3. If the finite element method is used, the optimal θ3 can be obtained by calculation by performing stress analysis on the model in FIG.

FIG. 9 is a top view of a detection apparatus according to a second embodiment of the present invention. In the apparatus shown in FIG. 8, the V axis and the W axis are defined at positions shifted by the shift angle θ3 from the X axis and the Y axis, respectively, and the respective resistance elements are arranged on these axes. On the other hand, in the embodiment shown in FIG. 9, the arrangement direction is inclined by the shift angle θ3 in a state where each resistance element is arranged on the detection axis without providing a special arrangement axis. That is, the resistance elements Rx1 to Rx4 for detecting the X-axis direction component are all arranged on the X-axis, but are arranged to be inclined by the predetermined angle θ3 with respect to the X-axis. Similarly, the resistance elements Ry1 to Ry4 for detecting the component in the Y-axis direction are all disposed on the Y-axis, but are disposed at a predetermined angle θ3 with respect to the Y-axis. The phase difference θ2 can also be canceled by such a method of inclining the arrangement direction.

In a conventional force / acceleration detecting device using a semiconductor substrate, a force component acting in the direction of the detection axis is detected by using a resistance element arranged on the detection axis along the detection axis. On this assumption, the detection of the force components in the X-axis and Y-axis directions defined on the main surface of the substrate has been performed. The present invention is based on the idea of canceling the phase difference of the detection sensitivity curve caused by the irregular shape of the annular groove by intentionally shifting the arrangement axis of the resistance element from the detection axis. Therefore, the present invention can be implemented in various modes other than the above-described embodiment without departing from this idea. For example, as the anisotropic etching method for a semiconductor substrate, various methods other than the above-described method can be performed. Further, in the above-described embodiment, a description has been given of a force / acceleration detection device. However, if a magnetic material is added to the point of action P, it is possible to detect a force indirectly acting by magnetism. Use as a magnetic detection device is also possible.

Finally, a novel technique for a self-diagnosis function applicable to the force / acceleration detecting device will be disclosed.
A technique for adding a self-diagnosis function to the force / acceleration detection device is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 3-200038. The technology disclosed in this publication is briefly described as follows. First, a semiconductor substrate 40 as shown in FIG. 10 is prepared. An annular groove is dug in the lower surface of the semiconductor substrate 40, and a plurality of resistance elements R are formed in an upper portion (flexible portion) of the groove. The arrangement of the resistance elements R is the same as that shown in FIG. 2. If a bridge circuit as shown in FIG. 3 is formed using these resistance elements R, the detection of the force / acceleration in the three axes of XYZ can be performed. Will be possible. FIG. 11 is a side sectional view of an actual acceleration detecting device configured using such a semiconductor substrate 40. A peripheral portion of the lower surface of the semiconductor substrate 40 is joined to the pedestal 41, and a central portion of the lower surface is joined to the weight 42. A control member 43 is further connected to the lower surface of the pedestal 41. After all, the weight 42 is suspended in the internal space formed by the pedestal 41 and the control member 43, and when acceleration acts on the weight 42, mechanical deformation occurs in the semiconductor substrate 40. Will be. Since the resistance value of each resistance element R changes due to this mechanical deformation, the direction and magnitude of the applied acceleration can be detected.

The features of the technology disclosed in this publication are as follows:
The point is that such an acceleration detection device is provided with a self-diagnosis function. That is, the upper cover member 5 is provided above the semiconductor substrate 40.
Make sure to put 0. The flat plate portion 51 of the upper lid member 50
Is arranged at a position facing the upper surface of the semiconductor substrate 40 at a predetermined distance, and a test electrode E0 is formed on the lower surface thereof. On the other hand, on the upper surface of the semiconductor substrate 40, as shown in FIG.
Test electrodes E1 to E4 (shown by hatching in FIG. 10 so that the shape can be easily recognized) are formed. Test electrodes E1 to E4 and test electrode E
0 means that the electrodes are arranged to face each other (the test electrode E0 is a common electrode that faces all of the test electrodes E1 to E4). If the test electrodes are arranged in this manner, a test of the acceleration detecting device can be performed by applying a voltage of a predetermined polarity to these electrodes. For example, if a positive voltage is applied to the electrodes E0 and E2 and a negative voltage is applied to the electrode E4, an attractive force acts between the electrodes E0 and E4 and a repulsive force acts between the electrodes E0 and E2 according to Coulomb's law. I do. As a result,
The same state as when the force in the X-axis direction acts on the weight body 42 can be created. As described above, by selectively applying voltages of various polarities to the respective electrodes, it is the same as the case where the acceleration of the specific magnitude acts in the specific direction even though the acceleration is not actually acting. You will be able to create a state. Therefore, if the change in the resistance element R at this time is detected by the bridge circuit, it can be tested whether or not the detection result is correct. Thus, the acceleration detection device having the structure shown in FIGS. 10 and 11 has a self-diagnosis function.

The self-diagnosis function described above has already been disclosed in
This is the content disclosed in Japanese Patent Application Publication No. 200038, and for the more detailed technical content, refer to the publication. What is newly disclosed here is a device relating to a wiring method in an apparatus having such a self-diagnosis function. FIG.
As shown in FIG. 0, a plurality of bonding pads B are arranged on both left and right sides of the semiconductor substrate 40. When this device is housed in an IC package, these bonding pads B and the leads on the package side are connected to each other. Are connected by a bonding wire. Therefore, wiring for electrically connecting each resistance element / electrode and a predetermined bonding pad B is required. Here, the wiring for the resistance element R and the electrodes E1 to E4 on the semiconductor substrate 40 has no particular problem. Various techniques have already been known as a method for forming a wiring layer on a semiconductor substrate. For example, FIG.
As shown in (1), the electrode E1 may be connected to the bonding pad B using a wiring layer C such as aluminum formed on the surface of the semiconductor substrate 40. However, the wiring connecting the electrode E0 on the upper lid member 50 and the bonding pad B on the semiconductor substrate 40 is not limited to this. Here, a method for efficiently wiring the electrode E0 is disclosed.

FIG. 12A is a side view of the upper lid member 50, and FIG. 12B is a bottom view thereof. The figure which looked at the figure (b) from the left direction of the figure corresponds to the figure (a). As shown,
The upper lid member 50 is composed of a flat plate portion 51 and a pair of side leg portions 52 that support the sides thereof, and the material is glass in this example. The test electrode E0 is formed on the lower surface of the flat plate portion 51. The first feature to be noted here is that a part of the test electrode E0 extends to the bottom surface of the side leg portion 52 to form the contact electrodes E0a and E0b. This is because, as shown in FIG.
It is sufficient to adopt a structure in which a part of 0 is extended along the surface of the side leg portion 52. A second characteristic that should be noted is that a slit 53 is formed in a part of the side leg portion 52. The function of the slit 53 will be described later.

On the other hand, on the upper surface of the semiconductor substrate 40, FIG.
The following preparations are made to receive the upper lid member 50 as shown in FIG. The first preparation is to leave the portions of the regions A1 and A2 hatched in FIG. 13 where the semiconductor (silicon in this example) is exposed. In other words, no insulating film or the like is formed in this region. This is because the upper lid member 50 is anodically bonded in the areas A1 and A2. The second preparation is shown in FIG.
The contact electrodes E5a and E5b are formed at the positions shown in FIG. 3 and are connected to predetermined bonding pads B via the wiring layer C. This is to maintain electrical contact with the test electrode E0 on the upper lid member 50 side. The above preparations are preparations that can be performed on the semiconductor substrate 40, and can be performed simultaneously with the process of forming the resistance element R and the test electrodes E1 to E4.

When the preparation for receiving the semiconductor substrate 40 is completed, the upper lid member 50 shown in FIG. 12 is put on the semiconductor substrate 40 shown in FIG. FIG. 14 is a plan view showing this state, in which the upper lid member 50 is indicated by a chain line. FIG. 15 is a front view of the cover. As described above, the hatched areas A1 and A1 in FIG.
At A2, the semiconductor substrate 40 and the upper lid member 50 are anodically bonded. By doing so, the contact electrode E on the upper lid member 50 side
0a and E0b are contact electrodes E5a and E5a on the semiconductor substrate 40 side.
It comes into contact with E5b. This contact state is shown in FIG.
Are clearly shown. At this time, the upper lid member 50 floats by the thickness of both contact electrodes and the thickness of the insulating film 44 (for example, SiO ₂ film). However, since the slit 53 is formed, the position of the slit 53 is set. This causes the flat plate portion 51 of the upper lid member 50 to bend. And
A favorable contact state of the contact electrode is ensured by the stress generated based on the bending. In addition, the joining portion between the upper lid member 50 and the semiconductor substrate 40 is limited by the slit 53, and the joining area does not vary. Note that in each of the drawings in the above description, the insulating film 44 is illustrated only in FIG.
It is omitted in other drawings.

The above-described wiring structure can be applied to a capacitance type detection device as disclosed in, for example, JP-A-4-148833.

[0033]

As described above, according to the force / acceleration detecting apparatus of the present invention, the step of forming the annular groove in the semiconductor substrate is performed by anisotropic etching.
Low-cost manufacturing is possible, and the phase difference in detection sensitivity is offset by shifting the axis of the resistor element from the detection axis, so accurate detection without interference with other axes Becomes possible.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a conventionally proposed general force / acceleration detecting device.

FIG. 2 is a top view of the detection device shown in FIG.
The cross section taken along the line -A corresponds to FIG.

FIG. 3 is a diagram showing a detection circuit used in the detection device shown in FIG.

FIG. 4 is a top view of a force / acceleration detecting device in which an octagonal annular groove is formed by performing anisotropic etching on a silicon substrate.

FIG. 5 is a graph showing a piezoresistance coefficient in each direction of a silicon substrate (110) surface.

6 is a diagram showing a phase difference of detection sensitivity in the X-axis direction in the detection device shown in FIG.

FIG. 7 is a diagram showing a phase difference in detection sensitivity in the Y-axis direction in the detection device shown in FIG.

FIG. 8 is a top view of the force / acceleration detecting device according to the first embodiment of the present invention.

FIG. 9 is a top view of a force / acceleration detecting device according to a second embodiment of the present invention.

FIG. 10 is a top view of a semiconductor substrate for a detection device having a self-diagnosis function.

11 is a side sectional view of an acceleration detection device using the substrate of FIG.

12 is a side view and a bottom view of the upper lid member 50 in the apparatus shown in FIG.

13 is a top view of the semiconductor substrate prepared to attach the upper lid member 50 shown in FIG.

14 is a top view of the semiconductor substrate showing a state where the upper lid member 50 shown in FIG. 12 is attached.

FIG. 15 is a front view showing a state where the upper lid member 50 shown in FIG. 12 is attached.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Semiconductor substrate 11 ... Fixed part 12 ... Flexible part 13 ... Working part 20 ... Silicon substrate 21 ... Fixed part 22 ... Flexible part 23 ... Working part 30 ... Power supply 31-33 ... Potentiometer 40 ... Semiconductor substrate 41 ... Pedestal 42 weight member 43 control member 44 insulating film 51 flat plate 52 side leg 53 slit A1, A2 silicon exposed area B bonding pad C wiring layer E0-E4 test electrode E0a, E0b ... contact electrodes E5a, E5b ... contact electrodes P ... action points Rx1 to Rx4, Ry1 to Ry4, Ry1 to Ry4 ... resistance elements V, W ... arrangement axes X, Y, Z ... detection axes

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-38830 (JP, A) JP-A-4-84725 (JP, A) JP-A-3-202778 (JP, A) JP-A-5-202778 196525 (JP, A) JP-A-1-255279 (JP, A) JP-A-5-45244 (JP, A) JP-A-3-89130 (JP, A) JP-A-63-94129 (JP, A) JP-A-3-202778 (JP, A) JP-A-61-57543 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 5/16 G01P 15/12 G01P 15/18

Claims (6)

(57) [Claims] 1. A flexible portion having flexibility is formed by digging an annular groove on one surface of a semiconductor substrate, and a resistor having a piezoresistance effect is formed on the flexible portion on the other surface of the semiconductor substrate. A force / acceleration detecting device for arranging an element and detecting a predetermined detection axial component of a force or acceleration acting to cause bending of the flexible portion based on a change in resistance value of the resistance element; A polygonal annular groove is formed by using an anisotropic etching method, an arrangement axis is defined at a position shifted by a predetermined angle with respect to the detection axis, and on the arrangement axis, and along the arrangement axis. A force / acceleration detection device, wherein a resistance element is arranged in the direction, and the predetermined angle is set so that the detection sensitivity with respect to the detection axis direction component is maximized. 2. The detecting device according to claim 1, wherein a silicon substrate is used as a semiconductor substrate, and an annular groove is dug in a (110) plane of the substrate, and a distance of <00 from the detection axis.
1> A force / acceleration detection device, wherein an arrangement axis is defined at a position shifted by a predetermined angle toward a direction. 3. The detection device according to claim 2, wherein the surface on which the resistive element is arranged is at 45 ° with respect to the <001> direction.
, And the Y axis is defined in a direction orthogonal to the X axis, and the X axis is defined as <001>.
A V axis shifted by a predetermined angle in a direction approaching the direction and a W axis shifted by a predetermined angle in the direction approaching the <001> direction are defined by a resistance element disposed on the V axis. A force / acceleration detection device, wherein the X-axis direction component is detected, and the Y-axis direction component is detected by a resistance element arranged on the W axis. 4. A flexible portion having flexibility is formed by digging an annular groove on one surface of the semiconductor substrate, and a resistor having a piezoresistive effect is formed on the flexible portion on the other surface of the semiconductor substrate. A force / acceleration detecting device for arranging an element and detecting a predetermined detection axial component of a force or acceleration acting to cause bending of the flexible portion based on a change in resistance value of the resistance element; A polygonal annular groove is formed by using an anisotropic etching method, and a resistive element is arranged by being inclined at a predetermined angle on the detection axis, and the detection sensitivity with respect to the detection axis direction component is maximized. The force / acceleration detecting device, wherein the predetermined angle is set as described above. 5. The detection device according to claim 4, wherein a silicon substrate is used as the semiconductor substrate, and an annular groove is dug in the (110) plane of the substrate, so that a <00
1> A force / acceleration detecting device, wherein a resistance element is arranged in a direction inclined by a predetermined angle toward a direction. 6. The detection device according to claim 5, wherein the surface on which the resistive element is arranged is at 45 ° with respect to the <001> direction.
And a Y-axis in a direction perpendicular to the X-axis, and the resistance element is disposed on the X-axis in a direction inclined at a predetermined angle toward the <001> direction. A component in the X-axis direction is detected, and a component <
001> A force / acceleration detecting device, wherein the Y-axis direction component is detected by a resistance element arranged in a direction inclined by a predetermined angle toward the <001> direction.