JP4157414B2 - Capacitance type external force detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a capacitance-type external force detection device that facilitates mounting.
[0002]
[Prior art]
As a capacitance type external force detection device, a device as shown in FIG. 6 has been known (for example, refer to Patent Document 1).
[0003]
That is, there are a sensor chip 100 for detecting an external force and a chip 120 on which a signal processing circuit 121 is formed. In the sensor chip 100, an insulating film 101 and polysilicons 102, 103, and 104 are formed. The polysilicon 103 is connected by a beam (not shown), and the polysilicon 103 forms a weight that can be displaced by an external force. When the weight 103 is displaced by an external force, the capacitance formed by the gap between the polysilicons 102 and 104 changes. This change in capacitance makes it possible to measure the external force.
[0004]
The sensor chip 100 has a pad 105 for taking out its output to the outside, and the chip 120 has a pad 123 that receives the output from the sensor chip 100 as an input. Are electrically connected.
[0005]
A signal from the sensor chip 100 is connected to the chip 120 on which the signal processing circuit 121 is formed via the wire 110, and the signal processing circuit 121 calculates an external force.
[0006]
[Patent Document 1]
JP-A-10-206169 (page 2-3, FIG. 15)
[0007]
[Problems to be solved by the invention]
In the conventional electrostatic capacity type external force detection device, since the sensor and the signal processing circuit are connected by a wire, a pad for wire bonding is required for each, and both the sensor and the signal processing circuit have been increased in size. In addition, there is a problem that the detection accuracy of the sensor is lowered due to the parasitic capacitance of the wire.
[0008]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to obtain a capacitance-type external force detection device that detects a sensor and a signal processing circuit in a small size and with high accuracy in order to solve such a conventional problem.
[0009]
[Means for Solving the Problems]
The capacitance-type external force detection device according to the present invention includes a first insulator substrate, first and second through holes formed so as to penetrate from the front surface to the back surface of the first insulator substrate, And first and second wirings formed on the surface of one insulator substrate. Furthermore, it has the 1st semiconductor layer arrange | positioned at the back surface of a 1st insulator substrate, and the 1st insulating film arrange | positioned at the back surface of a 1st semiconductor layer. Furthermore, the first space formed in the first semiconductor layer, the second semiconductor layer disposed on the back surface of the first insulating film , and the second space formed in the second semiconductor layer And a weight formed in the second space, and a signal processing circuit for detecting displacement of the weight formed in the first semiconductor layer. The first wiring is connected to the first space on the lower surface of the first insulator substrate through the first through hole, and a part of the input and output of the signal processing circuit is the second It is connected to the surface of said 1st insulator board | substrate by the 2nd wiring through the through-hole.
[0010]
Furthermore, the capacitance-type external force detection device according to the present invention is characterized in that the first or second wiring is connected on the surface of the first insulator substrate.
[0011]
Furthermore, the capacitance-type external force detection device according to the present invention is characterized in that the second space is a vacuum.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the above problems, in the present invention, in the capacitive external force detection device, the sensor and the signal processing circuit are integrated, the signal line from the sensor is passed through the insulator above the sensor, Connected to the top, the signal line of the signal processing circuit also penetrates the insulator and connected to the top of the insulator, and on the top of the insulator, the signal line from the sensor and the signal line of the signal processing circuit are patterned conductors And connected.
[0013]
【Example】
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a capacitance type external force detection device showing a first embodiment of the present invention. A structure in which an SOI structure substrate in which a semiconductor 1 (hereinafter referred to as Si1), an oxide film 2 and a semiconductor 3 (hereinafter referred to as Si3) are stacked is processed by anisotropic etching or the like and functions as a weight. A body 4 and spaces 6 and 7 are formed. The weight 4 is supported on the Si 3 by a beam serving as a spring so that it can be displaced by an external force.
[0014]
Further, a signal processing circuit 5 is formed in Si1 by an IC planar process or the like. A conductor (for example, AL) wiring 15 connected to the input or output of the signal processing circuit 5 is formed on Si1.
[0015]
Si3 is (anodic) bonded to an insulator 10 serving as a pedestal, for example, glass. The insulator 11 has a through hole 16 (portion surrounded by a dotted line circle) and penetrates the front surface and the back surface of the insulator 11. In FIG. 1, the upper side of the insulator 11 is the front surface and the lower side (Si 1 side) is the back surface. On the back surface of the insulator 11, wirings 14 made of a conductor (for example, AL) and capacitive electrode / wiring patterns 13 are formed.
[0016]
When the weight 4 is displaced by an external force, the gap between the space 7 between the Si 1 and the capacitive electrode 13 changes, and the capacitance between the Si 1 and the capacitive electrode 13 changes. The external force can be measured by detecting this change in capacitance.
[0017]
The capacitive electrode 13 is connected to the front side of the insulator 11 through the through hole 16 of the insulator 11. On the front side of the insulator 11, there is a wiring 12 made of a conductor, and the wiring 12 and the capacitor electrode 13 are contacted and connected.
[0018]
On the other hand, the wiring 15 from the signal processing circuit 5 is in contact with the wiring 14 formed on the back surface of the insulator 11 and is formed on the front side of the insulator 11 through the through hole 16 of the insulator 11. Connected to the wiring 12.
[0019]
Next, connection between the wiring 15 from the signal processing circuit 5 and the wiring 14 formed on the back surface of the insulator 11 will be described. FIG. 2 shows a schematic diagram of the location. An oxide film 23 is formed on Si1, and a wiring 15 from a signal processing circuit (not shown in FIG. 2) is patterned thereon. An impurity type well 21 different from Si1 is formed in Si1 at a connection portion from the insulator 11 to the wiring 14.
[0020]
As shown in FIG. 2, by providing a gap 22 at the contact portion between the wiring 14 from the insulator 11 and Si1, a step is generated when the Si1 and the insulator 11 are joined, and the (anode) between the Si1 and the insulator 11 ) Prevents gaps from occurring during joining. The height of the gap 22 is made smaller than the sum (A + C) of the thickness A of the wiring 14 and the thickness C of the wiring 15. Further, the depth D of the well 21 is made deeper than the depth of the gap 22. A part of the wirings 14 and 15 enters the space 24 when the insulator 11 and Si1 are joined.
[0021]
As shown in FIG. 2, the connection between the wiring 15 from the signal processing circuit 5 and the wiring 14 formed on the back surface of the insulator 11 is not limited to the connection between the conductor (for example, AL) and the conductor (for example, AL). In addition, as shown in FIG. 3, there is a case where high-concentration impurities are diffused in the region of the active layer 1 where the active layer 1 and the wiring 14 are in contact. In FIG. 3, the outline of the connection location of the wiring 14 formed on the back surface of the insulator 11 and Si1 is shown.
[0022]
The conductor wiring 15 from the signal processing circuit (not shown in FIG. 3) forms a contact with the high-concentration diffusion 20 formed in the well 21 formed in Si1, and the high-concentration diffusion 20 is connected to the insulator 11. The wiring 15 from the signal processing circuit is electrically connected to the wiring 12 on the front side of the insulator 11 through the high-concentration diffusion 20 and the wiring 14 by making contact with the wiring 14 formed on the back surface of the insulating layer 11. The
[0023]
The high concentration diffusion 20 and the well 21 have the same impurity type, which is different from the impurity type of Si1. For example, the high-concentration diffusion 20 and the well 21 are n-type, and Si1 is p-type. When Si1 is p-type, the lowest potential of the signal processing circuit formed on Si1 is made equal to the potential of Si1. By doing so, the high concentration diffusion 20 and well 21 can be insulated from Si1.
[0024]
As shown in FIG. 3, by providing a gap 22 at the contact portion between the wiring 14 from the insulator 11 and Si 1, a step is generated at the time of joining Si1 and the insulator 11, and ( Anode) Prevents gaps from forming. The depth of the gap 22 is made shallower than the thickness A of the wiring 14. In order to ensure contact, the depth of the gap 22 is made shallower than the depth B of the high concentration diffusion 20.
[0025]
In FIG. 1, the substrate is an SOI structure in which Si1, oxide film 2 and Si3 are stacked. This is because when Si3 is etched when the weight 4 is formed, anisotropic dry etching of Si is performed. This is because the oxide film 2 can be used as an etching stop layer when performing. Therefore, if the etching stop condition is controlled by, for example, the etching rate and time, there is no need to use an SOI substrate.
[0026]
FIG. 4 is a plan view of the capacitance-type external force detection device of FIG. 1 according to the present invention. FIG. 1 is a cross-sectional view taken along the plane XX ′ of FIG. In FIG. 4, the hatched portion is a wiring (12 in FIG. 1) made of a patterned conductor. The circle in the wiring by the conductor of FIG. 4 is a through hole that connects the front surface and the back surface of the insulator 11.
[0027]
The conductor 12 can be realized by patterning after attaching a metal thin film to the insulator 11. As another method, the conductor 12 is a high-concentration semiconductor, the insulator 11 and the high-concentration semiconductor are bonded together by (anodic) bonding, and then the high-concentration semiconductor is thinned by polishing or the like to an appropriate thickness. It can also be realized by patterning a high concentration semiconductor.
[0028]
Further, after anodically bonding Si3 and the insulator 10, the insulators 11 and Si1, which are anodically bonded to the high-concentration semiconductor and block the through-holes, are anodically bonded in vacuum, whereby the spaces 6 and 7 of the weight 4 are vacuumed. It is possible to keep on. By keeping the space in a vacuum, the weight can move more easily than in the air, and a highly sensitive external force detection device can be manufactured.
[0029]
FIG. 5 shows a second embodiment of the present invention. The difference from FIG. 1 is that bumps 30 are formed on the wiring 12 patterned on the first insulator. The position of the bump 30 is on the through hole 16 in FIG. 5, but a bump may be formed other than on the through hole.
[0030]
After bump formation, surface mounting can be performed by placing the bump surface on the mounting substrate and heating.
[0031]
As described above, according to the present invention, the sensor for detecting the external force and the circuit for processing the signal are manufactured as the same element, and the output of the sensor and the signal processing circuit are connected through the through hole of the insulating substrate. Thus, it is possible to construct a highly accurate electrostatic capacity type external force detection device that is small in size and excellent in noise resistance.
[0032]
【The invention's effect】
The capacitance-type external force detection device of the present invention is advantageous in that it can be reduced in size and increased in accuracy.
[Brief description of the drawings]
FIG. 1 shows a capacitive external force detection device according to a first embodiment of the present invention. FIG. 2 shows a part of a capacitive external force detection device according to a first actual example of the present invention. FIG. 4 is a plan view of a capacitance-type external force detection device according to the first embodiment of the present invention. FIG. 5 is a plan view of the capacitance-type external force detection device according to the first embodiment of the present invention. Capacitance-type external force detection device [Fig. 6] Conventional capacitance-type external force detection device [Explanation of symbols]
1, 3 Si
2 Oxide film 4 Weight 5 Signal processing circuit 10, 11 Insulator 16 Through hole

Claims (3)

A first insulator substrate;
First and second through holes formed so as to penetrate from the front surface to the back surface of the first insulator substrate;
First and second wirings formed on the surface of the first insulator substrate;
A first semiconductor layer disposed on the back surface of the first insulator substrate;
A first insulating film disposed on the back surface of the first semiconductor layer;
A first space formed in the first semiconductor layer for detecting a change in shape by a change in capacitance ;
A second semiconductor layer disposed on the back surface of the first insulating film ;
A second space formed in the second semiconductor layer;
A weight disposed in the second space , the weight changing the shape of the first space by being displaced by an external force ;
A signal processing circuit for detecting displacement of the weight formed in the first semiconductor layer;
Have
The first wiring is connected to the first space on the lower surface of the first insulator substrate through the first through hole,
Part of the input and output of the signal processing circuit is connected to the surface of the first insulator substrate by the second wiring through the second through hole. Capacitive external force detection device.   2. The electrostatic capacity type external force detection device according to claim 1, wherein the first or second wiring is connected on a surface of the first insulator substrate. It said second space, capacitive force detection device according to claim 2, characterized in that the vacuum.

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