JPH11201848A - Capacitive sensor and detection method - Google Patents

Abstract

[Problem] To provide a capacitive sensor having high sensitivity and a wide measurement range regardless of a medium to be measured. A diaphragm 12 of a semiconductor substrate 10 is formed into a dome shape by receiving pressure. It bends and deforms. The central portion of the movable plate 16 that maintains the planar shape is locally connected and supported at the central portion of the diaphragm via the column portion 14. When the diaphragm is bent, the movable plate is displaced in parallel in the thickness direction. ,
The planar shape is maintained. Therefore, the second electrode 21 and the first electrode 20 are provided on the movable plate and the diaphragm and the like opposed thereto.
Is formed, the distance between the electrodes changes with the deformation of the diaphragm, and the capacitance generated between the electrodes also changes. Since the electrode-free surface of the diaphragm serves as the pressure receiving surface, the medium to be measured does not touch the electrodes and does not corrode. Further, when the diaphragm bends under pressure, it is displaced in a direction in which the distance between the electrodes is increased, so that the measurement range is increased with high sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type sensor and a detection method.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a conventional capacitance type sensor. As shown in FIG.
And the fixed substrate 2 are joined. A thin diaphragm 3 is formed at the center of the semiconductor substrate 1, and the fixed substrate 2 side of the diaphragm 3 is used as a movable electrode 4.
A fixed electrode 5 is formed on the surface of the fixed substrate 2 facing the substrate.
The movable electrode 4 and the fixed electrode 5 are separated by a predetermined distance, and a capacitance corresponding to the distance is generated between the two electrodes. Further, an appropriate space 6 is formed between the two electrodes, and the diaphragm 3 can be deformed in the space 6. Thus, when pressure is applied to the diaphragm 3 from the lower side in the figure, the diaphragm 2 receives the pressure and bends and deforms almost entirely into an upwardly convex dome shape, so that the distance between the two electrodes changes. Therefore, the amount of deflection of the diaphragm 3 and, consequently, the pressure applied to the diaphragm 3 can be measured from the change in capacitance generated between the electrodes.

Although not shown, for example, the fixed substrate 2
In some cases, a pressure introducing hole is formed in the space 6 so as to penetrate in the thickness direction so that the measured pressure can be introduced into the space 6. In the case of this type, since pressure is applied to the diaphragm 3 from the movable electrode 4 side, the diaphragm 3 bends away from the fixed substrate 2 (fixed electrode 5). At this time, the change in the distance between the fixed electrode and the diaphragm is largest at the center, and one of the electrodes is fixed to the fixed substrate, and the other electrode is provided on the diaphragm forming surface.

[0004]

In the case of a capacitance type sensor, there are various modifications, but it can be basically divided into the above two types. In the former type, in which the distance between the electrodes is reduced when the pressure is applied, the measurement medium does not enter the space 6, so even if the measurement medium is a special gas that corrodes the electrodes, the measurement medium may There is an advantage that measurement is possible because there is no touch. However, since the moving distance of the diaphragm 3 is restricted by the space 6, the moving distance cannot be made too large.
When the distance is increased, the capacitance in the reference state is small, and the change in capacitance at the start of the change of the diaphragm 3 is small. That is, there is a problem that the sensitivity is low and the measurable range is narrow.

Conversely, in the latter type in which the distance between the electrodes is increased when the pressure is applied, the sensitivity can be increased and the measurable range can be widened, contrary to the above.
Since the measurement medium touches the electrode, measurement of corrosive gas and the like cannot be performed, and there is a problem that the measurable medium is limited.

As described above, each type has advantages and disadvantages, and can be used properly according to specifications. Further, in the conventional capacitance sensors, the center of the diaphragm 3 changes most greatly. In other words, the periphery of the diaphragm has little change and is close to the parasitic capacitance. When the area of the diaphragm 3 is considered, it is natural that the area of the peripheral portion where there is not much change is larger than the area of the central portion where the change is large. as a result,
Even if the diaphragm 3 changes, the capacitance that changes based on the change is small due to the central portion having a small area.

Furthermore, in the conventional capacitance type sensor, the parallel displacement portion is only the central point of the diaphragm 3. That is, when the diaphragm 3 receives the pressure and bends and deforms almost entirely in a dome shape, the movable electrode 4 integrated therewith also bends and deforms in a dome shape, so that the distance between the movable electrode 4 and the fixed electrode 5 differs depending on the location. . There is also a problem that the non-uniform distribution of the electrode spacing deteriorates the linearity of the electric output with respect to the pressure input.

On the other hand, in order to solve the problem that there are few such parallel displacement parts, as shown in FIG. 1B, for example, a mesa 8 is provided on the semiconductor substrate 1 facing the fixed electrode 5, and the mesa 8 is provided. In some cases, the semiconductor substrate 1 is displaceably connected via a thin deformation region 9, and the opposing surface of the mesa 8 is a movable electrode 3. In the sensor having such a configuration, although the movable electrode 3 is displaced in parallel, the deformation area 9 is small, so that the elastic coefficient of the deformation area 9 is large, and it is difficult to detect a minute pressure handled by a micromachine. Furthermore, although the movable electrode 3 is displaced in parallel, it is displaced in the direction in which the gap is narrowed, so that it is impossible to achieve both high sensitivity and a wide measurement range. Even if the gap is displaced in the direction in which the gap is widened, the same problem remains because a large displacement cannot be obtained in the deformation region 9.

Further, in the conventional capacitance sensor, the movable electrode corresponding to the fixed electrode is only the diaphragm.
Then, the bottom surface of the frame around the semiconductor substrate 1 becomes the die bonding portion 1a, and the width of the die bonding portion 1a needs to be secured to some extent. Therefore, when the sensor is miniaturized, the die bond portion 1a cannot be made small, so that the area of the diaphragm 3 becomes small, and as a result, the electrode becomes small, so that the sensitivity also becomes small. Therefore, there is a limit to cost reduction due to miniaturization.

[0010] The present invention has been made in view of the above-mentioned background, and has as its object to solve the above-mentioned problems and to prevent corrosion of the electrode regardless of the type of the medium to be measured.
The sensitivity is high, the measurement range can be widened, and the linearity of the input / output characteristics can be improved. Also, the width of the die bond portion can be sufficiently set, and the electrostatic capacitance can be reduced. An object of the present invention is to provide a capacitive sensor and a detection method.

[0011]

In order to achieve the above object, in a capacitance type sensor according to the present invention, a substrate with a diaphragm, a column provided at the center of the diaphragm, and a A movable plate which is connected and is displaced in accordance with the deformation of the diaphragm, first and second electrodes respectively provided on opposing surfaces of the substrate and the movable plate, and capacitance generated between the first and second electrodes And a means for extracting a signal based on the data to the outside (claim 1). In addition, pillar part,
In the embodiment, the movable plate and the diaphragm are formed as a separate member by an insulating film. However, the present invention is not limited to this, and may be formed integrally with one member.

In addition, a substrate having a diaphragm, a movable plate connected to the diaphragm and moving in parallel with the deformation of the diaphragm while maintaining the initial shape, and a facing surface of the substrate and the movable plate are provided. It may be configured to include first and second electrodes and means for extracting a signal based on capacitance generated between the first and second electrodes to the outside (claim 2). That is, the diaphragm and the movable plate may be connected directly or indirectly.

[0013] Further, it has a substrate, a movable plate, and a column connecting them, and forms a diaphragm around the substrate to which the column is connected, and displaces the movable plate with the deformation of the diaphragm. The first and second electrodes may be provided on the opposing surfaces of the substrate and the movable plate, respectively (claim 4).

In each of the above-described configurations, the non-joining surface side of the diaphragm serves as a pressure receiving surface, and the movable plate moves in conjunction with the diaphragm, thereby causing a change in the sensor gap. Therefore, the measurement medium can be brought into contact only with the non-joining surface side of the diaphragm, and can be brought into a non-contact state with the electrode. Therefore, the measurement medium does not matter. Furthermore, when the diaphragm is deformed by receiving physical quantities such as pressure and acceleration, the movable plate connected via the column moves. At this time, although the diaphragm expands so that the pillar portion becomes convex, no physical quantity is added to the movable plate, and since the periphery (outer periphery) is open, the diaphragm is displaced in the reference state. Therefore, the distance of the movable plate in the area around the diaphragm and in the area facing the substrate increases. Therefore, by providing electrodes on the movable plate and the substrate, the displacement amount, that is, the physical amount, can be grasped as a change in capacitance.

Further, displacement when a physical quantity such as pressure is applied is in a direction in which the distance between the electrodes is increased. Therefore, the measurement limit pressure is large, the area where the gap change is large is wide,
It becomes a highly sensitive sensor.

Further, since the diaphragm and the movable plate are connected via the pillar provided at the center, the portion where the gap change is large is the peripheral region, so that the region where the gap change is large can be obtained most widely. .

The substrate can be formed of, for example, a semiconductor substrate. Further, the movable plate can be formed using a semiconductor substrate (including not only a semiconductor wafer but also a substrate on which a semiconductor is formed), a glass substrate, or the like. In the case where a semiconductor substrate is used, the cost can be significantly reduced because the glass substrate is not used.

Another solution is to provide a substrate having a diaphragm, a first electrode provided on an outer periphery of the diaphragm on the surface of the substrate, and connected to the diaphragm so as to be in parallel with the first electrode. A movable plate that moves with the deformation of the diaphragm while holding the diaphragm, a second electrode provided at a portion of the movable plate facing the first electrode, and static electricity generated between the first and second electrodes. Means for extracting a signal based on the capacitance to the outside can be provided (claim 3). By doing so, the first and second electrodes are displaced in parallel, so that the linearity of the sensor output with respect to the added physical quantity (input) is improved.

The detection method according to the present invention includes:
A base having a diaphragm (corresponding to the “semiconductor substrate 10” in the embodiment) and a movable plate connected to the diaphragm and moving with the deformation of the diaphragm are provided, and the base and the movable plate face each other. A first electrode and a second electrode are provided on the surface (the base side can be any part of the diaphragm part and / or the non-formed part) (the part where the electrode is provided may be the whole or part of the opposing surface), and the diaphragm By detecting a signal based on the capacitance generated between the two electrodes in accordance with the relative position of the two electrodes that changes with the displacement of the sensor, the amount of displacement of the diaphragm or the physical amount added to the diaphragm is detected ( Claim 5).

If the following means are taken as a more preferable structure of the present invention, more significant effects can be obtained in addition to the effects of the above-described basic structure.
That is, for example, the movable plate may have a planar shape larger than the diaphragm, and at least a part of the second electrode formed on the movable plate may be configured to face the substrate surface outside the diaphragm. it can. With such a configuration, the surface of the substrate on which no diaphragm is formed does not change even when pressure is applied. Further, the movable plate does not bend as described above.
Therefore, the first and second portions facing each other at the outer portion of the diaphragm
Since the electrodes are in a parallel displacement region, the linearity of the input / output characteristics is improved. Further, since the bonding portion can be widened, a sufficient capacity can be obtained with a smaller diaphragm, and the chip size can be reduced. Further, by reducing the diaphragm, the diaphragm spring coefficient increases, and as a result, the response speed increases.

[0021] The distance between the substrate and the movable plate around the column may be wider than the distance between the substrate and the movable plate near the periphery of the movable plate. That is, the gap around the column does not change much even when pressure is applied. Therefore, when an electrode is provided in such a portion, the capacitance does not change in that portion, and the portion becomes a parasitic capacitance.
Therefore, the parasitic capacitance is reduced by widening the gap in the region where the capacitance change is small, and as a result, the linearity of the input / output characteristics is improved.

In order to further improve the effect, it is preferable to provide a through hole in the movable plate around the column, for example. This further reduces the parasitic capacitance. Further, when the through-hole is provided, the through-hole serves as an air passage, so that responsiveness is improved.

Furthermore, the first and second electrodes may be provided only in a region where the diaphragm is not formed and a region opposed thereto. By doing so, the parasitic capacitance is further eliminated, and the linearity is improved.

On the other hand, an insulating film may be provided on at least one of the opposing surfaces of the movable plate and the substrate. That is, in the present invention, the gap moves in the direction in which it expands, but even if the movable plate and the diaphragm (substrate) come into contact with each other, there is no danger of short-circuiting, and resistance to humidity and the like is improved. At this time, if an insulating film having a higher dielectric constant than air is used, the capacitance is increased and the sensitivity is improved. When the purpose is to improve the sensitivity, the insulating film need not necessarily be a wide dielectric material. When such a material having a high dielectric constant is formed only on the peripheral portion of the movable portion (the region where the parallel displacement occurs), the capacitance increases only in the region where the parallel displacement occurs, the parasitic capacitance decreases, and the sensitivity improves.

Further, the means for extracting the signal based on the capacitance to the outside has a lead wire connected to the movable plate, and has a cutout cut into a predetermined position of the movable plate up to the vicinity of the pillar. A part may be provided, and a part of the lead wire may be disposed in the front notch, and one end of the lead wire may be connected to the vicinity of the pillar part on the back side of the notch. With this configuration, no extra stress is applied to the movable plate as compared with the case where the wiring is drawn out from the end of the movable plate, so that stable characteristics can be detected.

Further, the means for extracting the signal based on the capacitance to the outside has an extraction wiring connected to the movable plate, and the dummy wiring has a point symmetry with the extraction wiring with respect to the column. (Same substance, same shape) may be provided. With such a configuration, since the stress generated by the lead wiring is symmetrically applied to the movable plate, the inclination of the movable plate,
Twist and the like can be suppressed.

Further, the means for extracting the signal based on the capacitance to the outside may have an extraction wiring connected to the movable plate, and the stress of the extraction wiring may be smaller than that of the movable plate. As a method of reducing the stress, for example, a method of reducing the thickness or manufacturing a lead wiring using a material having low rigidity can be used. With this configuration,
The stress (spring force) generated by the lead wiring hardly affects the displacement of the diaphragm, so that the sensitivity and the responsiveness are improved.

[0028]

FIG. 2 shows a first embodiment of a capacitance type sensor according to the present invention. As shown in the figure, a thin diaphragm 12 is provided by removing a central portion of a lower end of a first semiconductor substrate 10 made of silicon, and a periphery of the diaphragm 12 becomes a frame 13. The lower surface of the frame 13 serves as a die bonding portion 13a. Also, diaphragm 1
A movable plate 16 is connected to the center of the upper surface of the second member 2 via a pillar 14 made of an insulator. The movable plate 16 is also composed of a second semiconductor substrate 18 made of silicon. Further, the movable plate 16 is formed of a flat plate having a substantially square shape in a plane, and floats in the air substantially independently of the surroundings (strictly speaking, the floating plate 16).
(They are connected to the diaphragm 12 via the pillars 14, and lead wires to be described later are connected to wire pads.)

Therefore, the diaphragm 12 and the movable plate 16 are in an insulated state, and the upper surface of the diaphragm 12 becomes the first electrode 20 and the lower surface of the movable plate 16 becomes the second electrode 21.
Then, a capacitance corresponding to the distance is generated between the electrodes 20 and 21. Such a configuration is a basic configuration, and in a reference state where no pressure is applied, as shown in the figure, the movable plate 16 and the diaphragm 12 both keep a substantially horizontal state, and the distance between the electrodes 20 and 21 is And height.

When an upward pressure is applied to the lower surface of the diaphragm 12 from this state, as shown in FIG. 3, the diaphragm 12 is displaced and bends into a dome shape which is upwardly convex. Then, since the movable plate 16 maintaining the planar shape is only locally supported at the center of the diaphragm 12 at the center thereof through the column portion 14, when the diaphragm 12 is bent and deformed into a dome shape, The movable plate 16 is displaced in parallel in the thickness direction while maintaining the planar shape. As a result, the gap between the peripheral edge of the diaphragm 12 and the movable plate 16 increases, so that the gap between the electrodes 20 and 21 in the portion widens, and the capacitance generated between the electrodes 20 and 21 changes. Then, the applied pressure can be measured based on the changed capacitance.

The point to be noted here is that the diaphragm 12
The gap portion between the electrodes 20 and 21 which changes based on the displacement of the diaphragm 12 is a peripheral portion of the diaphragm 12 having a large area. As a result, the amount of change in the capacitance when the diaphragm 12 changes to the same extent as in the related art increases, and the sensitivity becomes high. Further, the direction of displacement of the diaphragm 12 when pressure is applied is a direction in which the gap between the electrodes 20 and 21 is widened, so that the measurement range can be widened and the distance between the electrodes in the reference state can be shortened. But high sensitivity. Moreover, since the medium for measuring the pressure does not come into contact with the electrodes, the type of the measuring medium is not limited. Therefore, it is possible to simultaneously satisfy both requirements of increasing the sensitivity and the wide measurement range, which are conventionally the front and back sides, and regardless of the measurement medium. Further, since both the diaphragm 12 and the movable plate 16 are formed using a conductive semiconductor substrate, they are not affected by thermal distortion after joining.

In this embodiment, the diaphragm 12
Since both the (first electrode 20) and the movable plate 16 (second electrode 21) are formed of a semiconductor (silicon) substrate, a proper capacitance is generated between both electrodes 20 and 21, and
The following structure was further adopted to take out the generated capacitance.

That is, when the two semiconductor substrates 10 and 18 are joined, the insulating film 22 is interposed therebetween.
Each of the substrates 10 and 18 was connected to the insulating film 22.
As the insulating film 22, for example, the first semiconductor substrate 1
The oxide film can be formed by patterning the oxide film on the upper surface of the insulating layer 22, and the above-described column portion 14 can be manufactured using the insulating film 22.

Further, in order to prevent the electrodes 20 and 21 from coming into contact with each other and short-circuiting, the movable plate 16, that is, the surface on the bonding surface side (the lower surface in the figure) of the second semiconductor substrate 18 is made of an insulating protective film. 24. As a result, even if the movable plate 16 accidentally comes into contact with the diaphragm 12, no short circuit occurs because the protective film 24 exists between the two. Also, an insulating protective film 25 is similarly formed on the non-bonding surface side surface of the second semiconductor substrate 18 to prevent short circuit.

The mechanism for taking out the capacitance generated between the electrodes 20 and 21 to the outside is as follows.
On the 0 side, aluminum 22 is formed by forming a hole 22a in a part of the insulating film 22 to expose the lower first semiconductor substrate 10 and electrically connecting to the exposed first semiconductor substrate 10. The wire pad 26 is formed by sputtering. Thereby, the first electrode 20 is connected to the diaphragm 12,
Since the wire pad 26 is electrically connected to the wire pad 26 via the first semiconductor substrate 10, the wire pad 26 can be connected to an external device by connecting a bonding wire.

The second electrode 21 side is connected to the first semiconductor substrate 1 via a lead-out line 27 formed integrally with the movable plate 16.
The terminal portion 28 is connected to a terminal portion 28 formed above the zero frame 13 and a hole 25a is formed in a part of the protective film 25 formed on the upper surface of the terminal portion 28, and the terminal portion 28 located below the hole 25a. Is exposed, and aluminum or the like is sputtered so as to be electrically connected to the exposed terminal portion 28 to form a wire pad 29. As a result, the second electrode 21 is electrically connected to the wire pad 29 through the above-described path. Therefore, by connecting a bonding wire to the wire pad 29, the second electrode 21 can be connected to an external device.

Further, an insulating film 22 is formed on the upper surface of the frame 13.
The frame 30 is formed via the. Protective films 24 and 25 are formed on both upper and lower surfaces of the frame 30. The frame 30 is arranged so as to surround the periphery of the movable plate 16, and by providing the frame 30, collision of any object on the side surface of the movable plate 16 is suppressed as much as possible. Then, the movable plate 16, the lead wiring 27, the terminal 28, and the frame 30 are formed by the second semiconductor substrate 18. That is, the second semiconductor substrate 18 can be simultaneously formed by etching and patterning. On the other hand, the second semiconductor substrate 18
Since the lead-out wiring 27 is manufactured more rigidly than a conventional bonding wire or the like, it is necessary to prevent the lead-out wiring 27 from affecting the displacement of the movable plate 16.

Therefore, in this embodiment, the rigidity of the lead wiring 27 itself is reduced by making the lead wiring 27 elongated. Moreover, by making the length as long as possible, the elastic restoring force does not work when the movable plate 16 is displaced. That is, as shown in FIG. 2B, one end 27a of the lead-out wiring 27 is connected near one vertex of the movable plate 16, and the lead-out wiring 27 is arranged parallel to one side of the movable plate 16 and the other end 27b Is extended to the vicinity of another vertex of the movable plate 16. More preferably, the movable plate 1 is further extended.
6 may be formed along two adjacent sides (the lead-out wiring is bent in the middle).

FIGS. 4 and 5 show a second embodiment of the present invention. In the present embodiment, basically, the first
This embodiment is the same as the first embodiment, except that the dimensions of the diaphragm 12 are smaller than those of the movable electrode 16. And
The first electrode 20 has a surface facing the second electrode 21, that is, the upper surface 20a of the diaphragm 12, as well as
A part 20 b of the upper surface of the frame 13 of the first semiconductor substrate 10 also becomes the first electrode 20.

With this configuration, as is apparent from a comparison between FIG. 4A and FIG. 5, when pressure is applied, the diaphragm 12 bends and the gap between the electrodes 20 and 21 changes. In the region (between the electrode portion 20b formed on the upper surface of the frame 13 and the second electrode 21), the distance between the electrodes is displaced in parallel. The area obtained is wider.

Since the sensitivity is high even when the area of the diaphragm 12 is reduced, the width of the frame 13 can be increased, and the width of the die bonding portion 13a can be increased. Therefore, even if the sensor is downsized, the width of the die bond portion 13a for ensuring surface mounting while obtaining desired sensor characteristics can be ensured, so that further downsizing is possible. The other configuration and operation and effect are the same as those of the above-described first embodiment, and therefore, are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 6 shows a third embodiment.
This embodiment is based on the above-described second embodiment, and further improves the withstand voltage. That is, the insulating film 31 is formed so as to cover the upper surface of the electrode portion 20b located on the upper surface of the frame 13. By providing the insulating film 31, the protective film 2 is provided between the electrodes 20 and 21.
4 and the insulating film 31 exist, so that the
A short circuit between 0 and 21 is prevented. Note that the other configuration and operation and effect are the same as those of the above-described second embodiment, and thus the description thereof is omitted.

The insulating film 31 is made of SiN
It is preferable to use an insulating film having a high dielectric constant such as a film. That is, the physical distance is determined by the gap between the diaphragm 12 and the frame 13.
Even if the gap of the portion is equal (reference state), the capacitance generated at the gap of the frame 13 increases.
Therefore, the capacitance can be increased only in the region where the gap is changed in parallel and the gap interval is changed, so that the sensitivity can be increased and the linearity of the input / output characteristics can be improved. In such a structure, for example, the insulating film 31 can be formed by depositing an S1N film on the entire upper surface of the first semiconductor substrate 10 and removing portions other than necessary regions by dry etching or the like. Thereafter, the sensor of the present embodiment can be configured by forming the insulating film 22 (the pillar portion 14) and processing the same as a normal process such as bonding the second semiconductor substrate 18.

FIG. 7 shows a fourth embodiment of the present invention. In the present embodiment, the groove 32 is formed in a region around the column 14 on the lower surface of the movable plate 16 based on the first embodiment described above. That is, as is apparent from FIG.
The amount of change in the distance between the electrodes around is small. Therefore, when the capacitance generated between the electrodes 20 and 21 of the entire sensor is considered, the capacitance generated in the area around the column 14 is
Even if pressure is applied, it does not change much and becomes a parasitic capacitance. Therefore, by forming the groove 32 as shown in the drawing, widening the gap in the region, and reducing the capacitance generated at the electrode portion opposed to the groove 32, the parasitic capacitance is reduced and the input / output is reduced. The linearity of characteristics was improved.

The type in which the grooves 32 are provided to reduce the parasitic capacitance is not limited to the type shown in the figure. For example, as shown in FIG. The groove 32 may be formed including a portion to be connected, and the pillar portion 14 may be connected to a substantially central position of the groove 32. Further, as shown in FIGS. 9A and 9B, a groove 33 may be provided on the diaphragm 12 side. Furthermore,
It is also possible to implement them by appropriately combining them.

Further, in the case of the structure as shown in FIGS. 8 and 9B, since the pillar 14 only needs to be located substantially at the center of the grooves 32 and 34, FIGS. 7 and 9A. Assembling can be performed easily as compared with those of the above. 7 and 8, a predetermined position on the lower surface of the second semiconductor substrate 18 (the portion where the groove 32 is formed) is removed by etching, and then a protective film is formed. It can be easily manufactured by joining it to the first semiconductor substrate 10 having the insulating film 22.

Further, the fourth embodiment described above can be applied to the second embodiment (a type in which the area of the diaphragm is reduced and the region where the distance between the electrodes is parallel displaced is increased). As an example, as shown in FIG. 10, a groove 32 can be formed around the column 14 on the lower surface of the movable plate 16. Of course, although not shown, a groove may be provided in the center of the lower surface of the movable plate 16 as shown in FIG. 8, and the upper end of the column portion 14 may be joined in the groove. Further, as shown in FIG. 11, a groove 33 may be provided at the center of the upper surface of the diaphragm 12, and the lower end of the column portion 14 may be connected in the groove 33. Of course, although not shown, a groove may be provided only around the pillar portion 14 as shown in FIG.

FIG. 12 shows a fifth embodiment of the present invention. In the present embodiment, the linearity of input / output characteristics is further improved based on the second embodiment. That is, of the movable plate 16, the diaphragm 1
A through-hole 35 is provided in a portion facing 2. Accordingly, the pillar portion 14 and the movable plate 16 are connected to each other by a beam 36 extending in a cross shape.
Are connected by The through hole 35 can be manufactured at the same time that the movable plate 16 is formed by etching the second semiconductor substrate 18.

With this configuration, since there is almost no conductor (only the beam portion 36) in the portion facing the diaphragm 12, the first electrode 2 formed on the first semiconductor substrate 10 side
0 is only the upper surface portion (or most) of the frame body 13 that is not displaced. Therefore, the parasitic capacitance is further reduced as compared with the above-described fourth embodiment, and almost all of the electrodes are parallel-displaced portions. Thereby, the linearity of the input / output characteristics is further improved.

Further, in the present embodiment, the provision of the through hole 35 allows the diaphragm 12 and thus the movable plate 16
When it is displaced, it becomes an air escape passage, so it can be smoothly displaced with little air resistance when moving, and it can detect even minute pressure, high frequency circumference and / or instantaneous pressure with high accuracy. It also has an effect. Note that the other configuration, operation, and effect are the same as those of the above-described embodiment (particularly, the second embodiment), and thus detailed description thereof will be omitted.

FIG. 13 shows a sixth embodiment of the present invention. This embodiment also improves the linearity of the input / output characteristics. As shown in the figure, unlike the above-described embodiments, the second electrode 38 is
A metal such as aluminum is formed on the surface of the protective film 24 formed on the lower surface of the substrate by sputtering or the like. The second electrode 38 is formed on a portion of the lower surface of the movable plate 16 that faces the frame 13 of the first semiconductor substrate 10.

With this configuration, the movable plate 16 formed of the second semiconductor substrate 18 becomes electrically non-conductive with the second electrode 38, so that the movable plate 16 becomes flat as the diaphragm 12 is deformed. It has a function of displacing while holding, that is, a function of displacing the second electrode 38 in parallel. Since the second electrode 38 is not provided around the column portion 14 on the lower surface of the movable plate 16, no capacitance is generated between the movable plate 16 and the upper surface of the diaphragm 12 (if it is generated, the capacitance is negligible). Accordingly, capacitance is generated between the second electrode 38, which is displaced in parallel when pressure is applied, and the first electrode 20 formed on the frame 13 opposed to (not displaced from) the input / output characteristics. The linearity is improved.

FIG. 14 shows a seventh embodiment of the present invention. The present embodiment relates to an improvement in a lead-out structure for conducting the second electrode to a wire pad 29 for drawing out to the outside. As a specific sensor structure, any of the above-described first to fifth embodiments can be applied. That is, in each of the above embodiments, the movable plate 1
In the present embodiment, the dummy wiring 39 is provided point-symmetrically with respect to the lead wiring 27 (the center of the movable plate 16: with reference to the column part 14). The dummy wiring 39 connects the side edge of the movable plate 16 to a pattern 40 formed at a predetermined position on the second semiconductor substrate 18. This pattern 40 corresponds to frame 3
0 is insulated.

With such a configuration, when the movable plate 16 is displaced, the same reaction force as that received from the extraction wiring 27 is also received from the dummy wiring 39. Therefore, the movable plate 1
Since the reaction force is applied to the entire plate 6 substantially uniformly, the movable plate 16 is not tilted or twisted. Therefore, the displacement is ensured while maintaining the parallel state of both electrodes. Although the wiring is provided in two places in the figure, for example, if the wiring is provided in four places in a swastika shape, the effect is further increased.

FIG. 15 shows an eighth embodiment of the present invention. The present embodiment is the same as the seventh embodiment in that the extraction wiring 27 and the dummy wiring 39 are arranged point-symmetrically, but each of the wirings 27 and 39 and the movable plate 16 are arranged.
The connection point with is different. That is, the movable plate 16
A band-shaped notch 16a is provided from the midpoint of each of the pair of opposite sides to the center. The back side of the notch 16a is
It is located on the pillar portion 14. Then, the lead wiring 27 and the dummy wiring 39 are inserted and arranged in the cutout portion 16 a and connected near the center of the movable plate 16. As a result, the wirings 27 and 39 are connected in the vicinity of the pillar 14 that moves with the displacement of the diaphragm 12, and the vicinity of the connection point is
Since the gap variation may be small, the reaction force on the diaphragm 12 side via the column portion 14 may be small. And
The stress of the wirings 27 and 39 is applied only to the vicinity of the column portion 14, and it is not necessary to consider the distortion of the movable plate 16 and the like. Furthermore, even if the shape of both wirings 27 and 39 is a single band, a sufficient length can be secured. Therefore, unlike the above-described embodiments, there is no need to extend the lead wiring 27 or the like along the gap between the movable plate 16 and the frame 30, so that the distance between the movable plate 16 and the frame 30 is reduced. And downsizing can be achieved.

FIG. 16 shows a ninth embodiment of the present invention. The present embodiment is a further improvement of the above-described eighth embodiment, in which the two wirings 2 that enter the notch 16a provided in the movable plate 16 and are connected near the pillar 14 are connected.
7, 39 are formed to extend a predetermined distance along the periphery of the movable plate 16 (two adjacent sides). Thereby, each wiring 2
7, 39 become parallel to the three sides of the movable plate 16, and the total extension distance becomes longer. Therefore, in the present embodiment, by making the two wirings 27 and 39 point-symmetric in the same manner as in the above-described seventh embodiment, the reaction force against the movable plate 16 is equalized. Similarly, by connecting near the pillar portion 14, the effect of reducing the generated reaction force itself is exhibited, and by increasing the length of both wires 27, 39, the stress of the wires 27, 29 is reduced. Thus, the movable plate 16 can be displaced in parallel more smoothly.

FIG. 17 shows a tenth embodiment of the present invention. The present embodiment is also an improvement of the extraction wiring 27, but can be applied to each of the above embodiments. That is, the lead wiring 27 is made thinner than the movable plate 16.
By doing so, the stress of the lead wiring 27 is reduced, and the influence of the stress on the movable plate 16 is reduced. In order to manufacture a sensor having such a structure, for example, before joining the second semiconductor substrate 18 to the first semiconductor substrate 10, the region where the lead wiring 27 is formed on the joining surface side of the second semiconductor substrate 18 is dry-etched or the like. Etching to make it thinner. Thereafter, the two semiconductor substrates can be bonded by fusion bonding, and can be manufactured by performing a normal manufacturing process.

In each of the above-described embodiments, the lead wiring for leading the second electrode 21 (movable plate 16) to the outside is provided by the second semiconductor substrate 18 for manufacturing the movable plate 16.
However, the present invention is not limited to this, and connection may be made using another member such as a bonding wire 43 as shown in FIG. In this example, a wire pad 44 is provided on the upper surface of the movable plate 16 (if a protective film is provided, a hole is formed in a corresponding portion of the protective film), and the wire pad 44 and the electrode pad 29 are provided.
Are connected to both ends of the bonding wire 43. The use of the bonding wire 43 in this manner is preferable in that the influence of the stress of the lead-out wiring is eliminated as in the above embodiments. In this case, if wire bonding is performed before forming the diaphragm, bonding can be easily performed.

FIGS. 19 and 20 show an eleventh embodiment of the present invention. In the present embodiment, unlike the above embodiments, the movable plate 46 is formed using a glass substrate. That is, first, the insulating film 49 is formed on the entire upper surface of the first semiconductor substrate 48 on which the diaphragm 47 is formed. Then, a wiring pattern 50 is formed by sputtering aluminum or the like at a predetermined position on the upper surface of the insulating film 49, and one end 50a of the wiring pattern 50 is widened to form a wire pad.

On the other hand, a convex portion 46a is provided at the center of the lower surface of the movable plate 46.
To form Then, aluminum or the like is sputtered on the periphery of the lower surface side of the movable plate 46, that is, on the portion of the first semiconductor substrate 48 facing the frame 51 to form a second electrode 53, and the second electrode 53 is formed continuously with the second electrode 53. A wiring pattern 55 extending to the protrusion 46a is also formed at the same time. An interconnection portion 57 is provided at the other end 50b of the wiring pattern 50, and the projection 46a is joined to the interconnection portion 57. Since the interconnection portion 57 is formed of aluminum, the second electrode 5
3 is a wiring pattern 50 → interconnection part 57 →
Conduction is made to the wire pad 50a through the wiring pattern 55. Then, a pillar portion is formed by the convex portion 46a and the interconnection portion 57. By using the interconnection in this way, the periphery of the movable plate can be set in a free state, so that no stress is applied to the movable plate,
The generation of distortion can be suppressed as much as possible.

The upper surface of the frame 51 of the first semiconductor substrate 48 facing the second electrode 53 becomes the first electrode 58, and a capacitance is generated between the two electrodes 53, 58 according to the distance between the gaps. The first electrode 58 is electrically connected to the outside through a wire pad 60 formed by sputtering aluminum on the first semiconductor substrate 48 exposed through a hole 49 a formed at a predetermined position in the insulating film 49. It becomes possible.

FIG. 21 shows a twelfth embodiment of the present invention. In the present embodiment, the cover 61 is formed so as to cover the space above the movable plate 16 based on each of the above embodiments. With such a configuration, entry of dust and the like into the gap can be prevented. When the cover 61 is formed by appropriately etching a semiconductor substrate such as silicon, the cover 61 can be manufactured by a series of processes using a semiconductor process.

To manufacture the sensors having the above-described configurations,
For example, a first semiconductor substrate and a second semiconductor substrate are respectively formed from separate silicon wafers. For example, after forming a pillar on the first semiconductor substrate, a second semiconductor substrate is formed on the upper surface of the pillar.
After bonding the semiconductor substrate, the semiconductor substrate can be manufactured using a semiconductor process by performing patterning by etching.

As another method, it can be manufactured, for example, by the method shown in FIG. That is, to form a counter electrode with a conductive thin film deposited on a diaphragm substrate using the surface microtechnology, the following is performed. (1) First, a silicon wafer 1 serving as a first semiconductor substrate
On the 0 ', a SiN film or the like is deposited, and the SiN is etched to form the pillars 14 and the like. (2) An oxide film 62 is deposited on a portion to be a gap.
This oxide film becomes a sacrificial layer. (3) The oxide film located above the pillars 14 is removed, polysilicon is deposited, and the movable plate 16 and the lead-out wiring are patterned. Of course, a protective film is also formed before and after the deposition of polysilicon. Thereby, the intermediate product of FIG. 22A can be formed. (4) The oxide film (sacrificial layer) manufactured in the process (2) is etched by wet etching to form a gap as described above. Thereby, the intermediate product of FIG. 22B can be formed. (5) The diaphragm 12 is formed by forming a pad for wire bonding and etching a predetermined position of the lower surface of the silicon wafer. Thus, a sensor as shown in FIG. 22C is manufactured. If sensor chips are made by such a process, it can be made with one wafer,
It leads to cost reduction.

Further, in the above step (3), the movable plate (second electrode) and the lead-out wiring are both formed of polysilicon. For example, the movable plate is made of single-crystal silicon, and the part of the lead-out wiring is formed by surface microtechnology. Therefore, if the gate electrode is made of polysilicon, the rigidity of the movable plate> the rigidity of the lead-out wiring is satisfied, and a structure in which the influence of the stress generated by the lead-out wiring is hardly applied to the counter electrode can be obtained.

In the above-described embodiments and application examples, an example in which the present invention is applied to a pressure sensor has been described. In that case, in order to make the diaphragm easily deformed by acceleration or the like, it is preferable to provide a weight projecting outward at the center of the diaphragm, for example.

[0067]

According to the capacitance type sensor and the detection method of the present invention, the change in capacitance due to the deformation of the diaphragm can be maximized in a large area on the peripheral side of the diaphragm. As a result, the change in the sensor output with respect to the change in the physical quantity to be measured increases, and the sensitivity becomes high. In addition, since the non-joining surface side of the diaphragm can be used as the pressure receiving surface of the measurement pressure, even when the physical quantity of the measurement target is pressure, the medium of the measurement target does not contact the electrode.
Therefore, there is no corrosion of the electrode regardless of the type of the medium to be measured. When the diaphragm bends, the movable plate joined thereto also moves and the distance between the two electrodes is increased, so that the sensitivity is high and the measurement range can be widened.

When the electrodes are formed around the substrate with the diaphragm, that is, in a region where the diaphragm is not formed, the distance between the electrodes is displaced in parallel at that portion, so that the linearity of the input / output characteristics can be improved. In addition, the width of the die bond portion can be sufficiently set, and the size can be reduced. Further, if the distance between the gaps near the pillar portion (including the substantial distance in consideration of the dielectric constant) is increased, the parasitic capacitance can be reduced, and the linearity of the input / output characteristics can be improved. Furthermore, if the structure of the lead wiring is devised, the stress on the movable plate can be reduced or adverse effects can be eliminated, so that the characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a conventional capacitance-type sensor.

FIG. 2 is a diagram showing a first embodiment of a capacitance type sensor according to the present invention.

FIG. 3 is a diagram showing a first embodiment of a capacitance type sensor according to the present invention.

FIG. 4 is a view showing a second embodiment of the capacitance type sensor according to the present invention.

FIG. 5 is a view showing a second embodiment of the capacitance type sensor according to the present invention.

FIG. 6 is a view showing a third embodiment of the capacitance type sensor according to the present invention.

FIG. 7 is a diagram showing a fourth embodiment of the capacitance type sensor according to the present invention.

FIG. 8 is a view showing a modification of the fourth embodiment of the capacitance type sensor according to the present invention.

FIG. 9 is a view showing a modification of the fourth embodiment of the capacitance type sensor according to the present invention.

FIG. 10 is a view showing a modification of the fourth embodiment of the capacitance type sensor according to the present invention.

FIG. 11 is a view showing a modification of the fourth embodiment of the capacitance type sensor according to the present invention.

FIG. 12 is a diagram showing a fifth embodiment of the capacitance type sensor according to the present invention.

FIG. 13 is a diagram showing a capacitance-type sensor according to a sixth embodiment of the present invention.

FIG. 14 is a diagram showing a capacitance-type sensor according to a seventh embodiment of the present invention.

FIG. 15 is a view showing an eighth embodiment of the capacitance type sensor according to the present invention.

FIG. 16 is a diagram showing a ninth embodiment of the capacitance-type sensor according to the present invention.

FIG. 17 is a diagram showing a tenth embodiment of the capacitance-type sensor according to the present invention.

FIG. 18 is a diagram showing a modification of the tenth embodiment of the capacitance-type sensor according to the present invention.

FIG. 19 is a view showing an eleventh embodiment of a capacitance-type sensor according to the present invention.

FIG. 20 is a diagram showing an eleventh embodiment of a capacitance type sensor according to the present invention.

FIG. 21 is a diagram showing a twelfth embodiment of a capacitance-type sensor according to the present invention.

FIG. 22 is a diagram illustrating an example of a manufacturing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 First semiconductor substrate 12 Diaphragm 13 Frame 13a Die bond part 14 Column part 16 Movable plate 18 Second semiconductor substrate 20 First electrode 21 Second electrode 22 Insulating film 24, 25 Protective film 27 Lead-out wiring 39 Dummy wiring

Claims (5)

[Claims] 1. A substrate with a diaphragm, a column provided at the center of the diaphragm, a movable plate connected to the column and displaced as the diaphragm is deformed, and a facing surface between the substrate and the movable plate. First and second
A capacitance type sensor comprising: a second electrode; and a unit for extracting a signal based on a capacitance generated between the first and second electrodes to the outside. 2. A substrate having a diaphragm, a movable plate connected to the diaphragm and moving in parallel with the deformation of the diaphragm while maintaining an initial shape, and provided on opposing surfaces of the substrate and the movable plate, respectively. First
A capacitance type sensor comprising: a second electrode; and a unit for extracting a signal based on a capacitance generated between the first and second electrodes to the outside. 3. A substrate having a diaphragm, and a first substrate provided on an outer periphery of the diaphragm on the surface of the substrate.
An electrode, a movable plate connected to the diaphragm and moving with the deformation of the diaphragm while maintaining a parallel state with respect to the first electrode, provided on a portion of the movable plate facing the first electrode. And a means for extracting a signal based on the capacitance generated between the first and second electrodes to the outside. 4. It has a substrate, a movable plate, and a column connecting them, and forms a diaphragm around the substrate to which the column is connected, and displaces the movable plate as the diaphragm is deformed. A capacitive sensor in which first and second electrodes are respectively provided on opposing surfaces of the substrate and the movable plate. 5. A base having a diaphragm, and a movable plate connected to the diaphragm and moving with the deformation of the diaphragm are provided, and a first and a second plate are provided on opposing surfaces of the base and the movable plate, respectively. By providing an electrode, by detecting a signal based on the capacitance generated between the two electrodes according to the relative position of the two electrodes that changes with the displacement of the diaphragm, the amount of displacement of the diaphragm or the physical amount added to the diaphragm The detection method to detect.