JP5298332B2 - Capacitance type sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a capacitance type sensor for detecting capacitance and a method for manufacturing the same.

FIG. 12 shows an example of a cross-sectional structure of a conventional sensor.
The conventional sensor 100 has a sandwich structure composed of a member 101 and members 102 and 103 sandwiching the member 101 in the vertical direction (Z direction).

  The member 101 includes conductor layers 101a and 101b (Si) and an insulating layer 101c sandwiched between the conductor layers 101a and 101b. The member 101 has a structure separated into a weight 104 provided at the center thereof, a pillar 105 provided around the weight 104, and a frame 106 (Si frame) provided at the outer periphery. Yes.

  In the upper member 102, the first electrode 107 (Z +) is disposed at a position facing the weight 104, and in the plurality of holes 108 having a via structure, electrical wiring 109 for detecting a signal is provided. Has been made.

  A second electrode 110 (Z−) is disposed on the lower member 103 at a position facing the weight 104.

  In the sensor 100 having such a structure, a change in the position of the weight 104 displaced by the inertial force is detected as a change in capacitance by the first and second electrodes 107 and 110 facing the weight 104. Based on the detection result, the inertial force is measured from the displacement amount of the weight 104.

“5-axis motion sensor using SOI wafer and its design method”, D. E, Vol. 126, No. 6, 2006, p. 261-p. 268

  In the case of the sensor 100 as shown in FIG. 12, the upper and lower members 102 and 103 are provided with the first and second electrodes 107 and 110, respectively. However, when the sensor is assembled, a signal can be taken out of the sensor. In addition, it is necessary to electrically connect one member 102 to the other member 103.

  The column 105 of the member 101 is provided to make an electrical connection between the member 102 and the member 103. The column 105 has a structure in which a conductor is formed by an insulating layer 101c. The layers 101a and 101b are insulated from each other.

  Therefore, in the conventional sensor 100, it is necessary to establish conduction between the conductor layers 101a and 101b by forming the electrode 111 with the lower conductor layer 101b constituting the pillar 105 having a via structure.

  In this case, the larger the size of the weight 104, the greater the signal intensity and the less susceptible to external noise. On the other hand, since the column 105 is included, the sensor size is very large. Become.

  Further, in the conventional sensor 100, since the potential of the weight 104 and the potential of the frame 106 are set to the same potential, the column 105 that is electrically separated from the frame 106 is changed from one member 102 to the other member. It is necessary to connect to 103, and the size of the sensor increases.

  Further, the via structure formed in the pillar 105 requires a large area for stable conduction in manufacturing, and as a result, the pillar 105 cannot be made small and the sensor is enlarged.

  FIG. 13 shows an example of a sensor 200 in which a conventional signal detection function and a signal processing function are integrated.

  This sensor 200 shows a configuration example in which the sensor 100 of FIG. 12 and a signal processing IC (integrated circuit) substrate 150 for processing a detected signal are integrated by resin molding.

  In this case, the sensor 100 and the signal processing IC board 150 are electrically connected through the lead wire 160. However, in such a separate structure, noise is likely to be carried on the lead wire 160, and necessary signals are transmitted. It cannot be detected accurately. In addition, in order to accurately detect a necessary signal, it is necessary to increase the size of the weight 104 to some extent to obtain a signal intensity of a certain level or more. Cannot be downsized.

  Accordingly, an object of the present invention is to provide a capacitance type sensor that can be miniaturized and a method for manufacturing the same.

  Another object of the present invention is to provide a capacitive sensor capable of accurately detecting a desired signal by reducing the number of connecting wires as much as possible to reduce noise and providing a manufacturing method thereof. There is to do.

  The present invention is a sensor for detecting capacitance, and includes a first conductive layer, a second conductive layer, and an insulating layer formed between the first conductive layer and the second conductive layer. A first member; a second member provided on a surface of the first member on the first conductive layer side and having a first electrode for detecting a capacitance; and the first member. A third member provided on a surface on the second conductive layer side and having a second electrode for detecting capacitance, wherein the first member is formed of the first electrode and the second electrode. A weight part disposed between the beam part, a beam part movably supporting the weight part, a frame part connected to the beam part and provided between the second member and the third member; The frame portion is used as a wiring for connecting the first electrode of the second member, and is electrically connected to the third member. In an electrically insulated state with respect to parts, characterized in that via said beam portion is electrically connected to the third member.

The first member includes a first silicon layer as the first conductive layer, a second silicon layer as the second conductive layer, and a SiO ₂ layer as the insulating layer.

  In the frame portion, the first conductive layer and the second conductive layer are electrically connected by removing a part of the insulating layer along the outer surface.

  The third member includes a driving electrode that applies simple vibration to the weight portion in order to measure angular velocity.

  The second electrode provided on the third member includes a plurality of electrodes for detecting a plurality of predetermined axial capacitances.

  The third member is formed of a semiconductor integrated circuit substrate having a signal processing function for processing the detected capacitance.

  The present invention is a method for manufacturing a capacitive sensor, comprising: a first conductive layer; a second conductive layer; an insulating layer formed between the first conductive layer and the second conductive layer; Forming a weight part, a beam part movably supporting the weight part, and a frame part connected to the beam part, and a first member having A step of attaching a second member having a first electrode for detecting capacitance to the surface on the first conductive layer side; and a region of the frame portion and the weight portion of the first member. Removing a part of the insulating layer to form a connection electrode for electrically connecting the first conductive layer and the second conductive layer; and the first electrode formed with the connection electrode. Attaching a third member having a second electrode for detecting capacitance to the surface of the member on the second conductive layer side, and The frame portion is used as a wiring for connecting the first electrode of the second member, and is electrically connected to the third member. The weight portion is electrically connected to the frame portion. It is characterized in that it is electrically connected to the third member in an insulated state.

  According to the present invention, a first member having a first conductive layer, a second conductive layer, and an insulating layer, a second member having a first electrode, and a third member having a second electrode, The first member includes a weight part, a beam part that movably supports the weight part, and a frame that is connected to the beam part and is provided between the second member and the third member. The weight portion and the frame portion are electrically insulated, and the frame portion is used as a connection wire for the first electrode of the second member and is electrically connected to the third member. The weight portion is electrically connected to the third member via the beam portion while being electrically insulated from the frame portion, so that a conventional column structure is unnecessary. Thus, the sensor structure can be greatly reduced in size.

  Further, according to the present invention, since the third member is configured as a semiconductor integrated circuit substrate having a signal processing function, there is no need for an external lead line as in the prior art, and the number of connection wirings is reduced as much as possible. The structure is difficult to paste, and a desired signal can be measured accurately.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First example]
A first embodiment of the present invention will be described with reference to FIGS.
<Configuration>
FIG. 1 shows a cross-sectional structure of a capacitive sensor 1 according to the present invention.

  The capacitance type sensor 1 includes a first member 2, a second member 3, and a third member 4.

The first member 2 includes a first conductive layer 5, a second conductive layer 6, and an insulating layer 7 formed between the first and second conductive layers 5 and 6. In this case, the first member 2 is an SOI (Silicon On) using a first silicon layer as the first conductive layer 5, a second silicon layer as the second conductive layer 6, and a SiO ₂ layer as the insulating layer 7. You may comprise as a board | substrate of an insulator) structure.

  The second member 3 is provided on the surface of the first member 2 on the first conductive layer 5 side. The second member 3 is formed with a first electrode 8 (Z +) for detecting the electrostatic capacitance in the Z-axis direction. As the second member 3, a glass substrate can be used.

  The third member 4 is provided on the surface of the first member 2 on the second conductive layer 6 side. The third member 4 is provided with a plurality of second electrodes 9. As a part of the plurality of second electrodes 9, an electrode 9a (Z-) for detecting electrostatic capacity in the Z-axis direction is formed at a position facing the first electrode 8 (Z +). As this third member 4, a semiconductor substrate can be used.

  The first member 2 includes a weight part 10, a beam part 11, and a frame part 12. In this case, the weight portion 10 is disposed between the first electrode 8 and the second electrode 9. The beam portion 11 movably supports the weight portion 10 and is connected to the frame portion 12. The frame portion 12 is disposed on the periphery of the weight portion 10 and is provided between the second member 3 and the third member 4.

  The frame portion 12 is used as a connection wiring for the first electrode 8 of the second member 3. In this case, a connecting electrode 20 for electrically connecting the first conductive layer 5 and the second conductive layer 6 to the frame portion 12 by removing a part of the insulating layer 7 along the outer surface thereof. Is installed. Thereby, the frame portion 12 is electrically connected to the third member 4 via the connection electrode 20.

  The weight part 10 is electrically insulated from the frame part 12. In this case, the weight portion 10 is electrically connected to the third member 4 via the connection electrode 21 attached to the lower surface side of the beam portion 11.

  FIG. 2 is a plan view showing a wiring structure on the surface of the third member 4 on the bottom side in FIG. FIG. 3 is a plan view seen from the first member 2 on the upper surface side of FIG.

  In the third member 4, electrodes 9 a, 9 b, 9 c, 9 d, and 9 e for detecting electrostatic capacitances in the X, Y, and Z axial directions are formed as the plurality of second electrodes 9. The electrode 9a is disposed at the center and is an electrode (Z−) for detecting the electrostatic capacitance in the Z-axis direction as described above. The pair of electrodes 9b and 9c are electrodes (X +, X−) for detecting electrostatic capacity in the X-axis direction. The pair of electrodes 9d and 9e are electrodes (Y +, Y−) for detecting the electrostatic capacitance in the Y-axis direction.

  The connection portion 30 is an electrode pad and is formed in the outer peripheral region of the third member 4 so as to face the frame portion 12. The connection portion 30 is solder-connected to the connection electrode 20 attached to the frame portion 12 and has the potential of the first electrode 8.

  The connection part 31 is an electrode pad, and is solder-connected to the connection electrode 21 attached to the lower surface side of the beam part 11, and has a potential of the weight part 10.

  The connection part 32 is an electrode pad, and is provided in the electrodes 9a, 9b, 9c, 9d, and 9e for detecting electrostatic capacitances in the X, Y, and Z axial directions.

  In addition, a driving electrode (not shown) for applying simple vibration to the weight portion 10 may be formed on the third member 4 in order to measure the angular velocity.

<Operation>
4 and 5 show the operation of the capacitive sensor 1 according to the present invention.

  FIG. 4 shows a change in capacitance when a force Fx is applied in the X direction (the same applies to the Y direction).

  When the force Fx is applied, the weight part 10 is tilted from the equilibrium state, and accordingly, the static electricity between the electrode 9b (X +) as the second electrode disposed on the third member 4 and the weight part 10 is obtained. The capacitance Cx + and the capacitance Cx− between the electrode 9c (X−) and the weight portion 10 change. In this example, the value of the electrostatic capacity Cx + becomes large and the value of the electrostatic capacity Cx− becomes small, whereby the magnitude of the force Fx in the X-axis direction can be detected.

  FIG. 5 shows changes in capacitance when a force Fz is applied in the Z direction.

  When the force Fz is applied, the weight portion 10 is tilted from the equilibrium state, and accordingly, the capacitance Cz + between the first electrode 8 (Z +) and the weight portion 10 and the electrode as the second electrode The electrostatic capacitance Cz− between 9b (Z−) and the weight portion 10 changes. In this example, the value of the electrostatic capacitance Cz + becomes large, and the value of the electrostatic capacitance Cz− becomes small, whereby the magnitude of the force Fz in the Z-axis direction can be detected.

By converting the change values of the capacitances Cx +, Cx−, Cy +, Cy−, Cz +, Cz− detected for each axis in this way into voltages using a CV converter, It becomes possible to detect acceleration, angular velocity, and Coriolis force.
[Second example]
A second embodiment of the present invention will be described with reference to FIGS. In addition, about the same part as the 1st example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

  6 and 7 show a method for manufacturing the capacitive sensor 1.

  First, each step of FIGS. 6A to 6D will be described.

In Step A of FIG. 6A, an SOI (Silicon On Insulator) substrate 2 is prepared as a first member. The SOI substrate 2 includes a first silicon layer 5 as a first conductive layer, a second silicon layer 6 as a second conductive layer, and a SiO ₂ layer 7 as an insulating layer.

  In Step B of FIG. 6B, gaps 40 and 41 for detecting capacitance are formed on the surfaces of the first silicon layer 5 and the second silicon layer 6.

In step C of FIG. 6C, the surface of the SiO ₂ layer 7 is reached from a part of the gap 40 on the first silicon layer 5 by using a dry reactive ion etching (D-RIE) method. A hole 42 is formed by selective etching.

In step D of FIG. 6D, the SiO ₂ layer 7 located below the hole 42 is removed by selective etching to form the weight portion 10.

  Through the above steps A to D, the weight portion 10 and the frame portion 12 are created in the first member 2.

  Next, each step of FIGS. 7A to 7E will be described.

  Step E in FIG. 7A is performed subsequent to step D in FIG. In this step E, a glass substrate 3 as a second member having a first electrode 8 for detecting capacitance is attached to the surface of the first silicon layer 5 of the SOI substrate 2. In this case, the glass substrate 3 is bonded to the frame portion 12 of the first silicon layer 5 using an anodic bonding method.

In Step F of FIG. 7B, selective etching is performed from the surface of the second silicon layer 6 of the SOI substrate 2 until it reaches the surface of the SiO ₂ layer 7 to form the holes 43.

In step G of FIG. 7C, the SiO ₂ layer 7 located below the hole 43 is removed by selective etching to form the beam portion 11.

In step H of FIG. 7D, metal is deposited on the first silicon layer 5 corresponding to the position of the hole 43 of the weight portion 10 and the second silicon layer 6 of the beam portion 11 to connect the connection electrodes 20, 21, 22 are formed. In this case, the connection electrode 20 electrically connects the first silicon layer 5 and the second silicon layer 6 by removing a part of the SiO ₂ layer 7 along the outer surface in the frame portion 12.

  In step I of FIG. 7E, the semiconductor substrate 4 as the third member having the second electrode 9 for detecting the capacitance is mounted on the second silicon layer 6 on which the connection electrode 21 is formed. . In this case, the connection electrodes 20 and 21 are opposed to the connection portions 30 and 31 on the semiconductor substrate 4 and attached by soldering.

  Through the above steps E to I, the weight portion 10 and the frame portion 12 are electrically connected to the semiconductor substrate 4 while being electrically insulated from each other.

  The frame portion 12 is used as a connection wiring for the first electrode 8 of the glass substrate 3 and is electrically connected to the semiconductor substrate 4 via the connection electrode 20.

  As described above, the frame itself is used as the electrical connection wiring between the second member 2 and the third member 4 in a state where the weight portion 10 and the frame portion 12 are electrically insulated. A column structure becomes unnecessary, and the sensor structure can be greatly reduced in size.

<Application example>
8 and 9 show an application example of the method for manufacturing the third member 4.
In step 1 of FIG. 8A, a semiconductor integrated circuit substrate (LSI substrate) 40 having a signal processing function for processing the detected capacitance is prepared as the third member 4. On the LSI substrate 40, an SiN layer 41 and an IC pad 42 are formed in advance.

  In step 2 of FIG. 8B, a polyimide layer 43 is formed on the SiN layer 41.

  In step 3 of FIG. 8C, a UBM (Under Bump Metal) 44 is formed on the polyimide layer 43.

  In step 4 of FIG. 8D, a resist film 45 is partially applied on the UBM 44 in order to perform rewiring.

  In step 5 of FIG. 8E, copper rewiring plating 46 is performed on the UBM 44 other than the resist film 45.

  In step 6 of FIG. 8F, the resist film 45 is removed.

  Step 8 in FIG. 9A is performed subsequent to step 6 in FIG. In step 6, a resist film 47 is partially applied to perform solder plating.

  In step 8 of FIG. 9B, solder plating 48 is performed on hole portions other than the resist film 47.

  In step 9 of FIG. 9C, the resist film 47 is removed to expose the copper rewiring plating 46 and the solder plating 48 on the substrate surface.

  In step 10 of FIG. 9D, the UBM 44 is removed and the IC pad 42 is exposed.

  Thus, the IC pad 42, the copper rewiring plating 46, and the solder plating 48 are formed on the LSI substrate 40. The copper rewiring plating 46 corresponds to the second electrode 9 of FIG. The solder plating 48 corresponds to the connection portion 31 in FIG. The IC pad 42 corresponds to the connection unit 30 in FIG.

[Third example]
A third embodiment of the present invention will be described with reference to FIGS. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

  FIG. 10 shows a configuration example of the capacitive sensor 1 having a capacitance detection function and a signal processing function.

  The capacitive sensor 1 includes an SOI substrate 2 as a first member, a glass substrate 3 as a second member, and an LSI substrate 40 as a third member, and is molded integrally with a resin 50. Has been.

  FIG. 11 is a diagram illustrating the function of the capacitive sensor 1.

  The capacitance type sensor 1 includes a signal detection unit 60 and a signal processing unit 70.

  The signal detection unit 60 includes the SOI substrate 2 and the glass substrate 3, and detects the values of the capacitances Cx +, Cx−, Cy +, Cy−, Cz +, and Cz− in the X, Y, and Z axis directions, respectively. .

  The signal processing unit 70 is configured by the LSI substrate 40, and includes a CV conversion unit 71 that converts a capacitance value into a voltage value, a measurement unit 72 that measures various signals of acceleration, angular velocity, and Coriolis force, and measures various signals. In order to do so, a drive unit 73 that applies simple vibration to the weight unit 10 is provided.

  As described above, since the third member is constituted by the LSI substrate 40 having a signal processing function, a conventional lead-out line is unnecessary, the number of connection wirings is reduced as much as possible, and noise is hardly applied. The desired signal can be accurately measured.

FIG. 4 is a cross-sectional view showing a structure of the capacitive sensor according to the first embodiment of the present invention and showing a cross section taken along line A-A ′ of FIG. 3. It is a top view which shows the surface shape of the 3rd member in the electrostatic capacitance type sensor of FIG. It is the top view seen from the 2nd member in the electrostatic capacitance type sensor of FIG. It is explanatory drawing which shows the detection principle of the electrostatic capacitance in the weight part of an electrostatic capacitance type sensor. It is explanatory drawing which shows the detection principle of the electrostatic capacitance in the weight part of an electrostatic capacitance type sensor. It is process drawing which shows the manufacturing method of the capacitive sensor which is the 2nd Embodiment of this invention. FIG. 7 is a process diagram illustrating a method for manufacturing the capacitive sensor subsequent to FIG. 6. It is process drawing which shows the manufacturing method of an electrostatic capacitance type sensor at the time of comprising a 3rd member as a LSI substrate. It is process drawing which shows the manufacturing method of the electrostatic capacitance type sensor following FIG. It is sectional drawing which shows the structure of the electrostatic capacitance type sensor provided with the signal processing function which is the 3rd Embodiment of this invention. It is explanatory drawing which shows the function of an electrostatic capacitance type sensor. It is sectional drawing which shows the structural example of the conventional sensor. It is sectional drawing which shows an example of the sensor provided with the conventional signal processing function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitance type sensor 2 1st member (SOI substrate)
3 Second member (glass substrate)
4 Third member (semiconductor substrate)
5 First conductive layer (first silicon layer)
6 Second conductive layer (second silicon layer)
7 Insulating layer (SiO ₂ layer)
8 First electrode 9 Second electrode 9a, 9b, 9c, 9d, 9e Electrode 10 Weight part 11 Beam part 12 Frame part 20, 21, 22 Connection electrode 30, 31, 32 Connection part 40 Semiconductor integrated circuit substrate (LSI substrate)
41 SiN layer 42 IC pad 43 Polyimide layer 44 UBM
45 Resist film 46 Copper rewiring plating 47 Resist film 48 Solder plating 50 Resin 60 Signal detection unit 70 Signal processing unit 71 CV conversion unit 72 Measurement unit 73 Drive unit 100 Conventional sensor 101, 102, 103 Member 101a, 101b Conductor layer (Si)
101c Insulating Layer 104 Weight 105 Column 106 Frame 107 First Electrode 108 Hole 109 Electrical Wiring 100 Sensor 110 Second Electrode 111 Electrode 150 Signal Processing IC Board 160 Leader Line 200 Sensor

Claims (9)

A sensor for detecting capacitance,
A first member having a first conductive layer, a second conductive layer, and an insulating layer formed between the first conductive layer and the second conductive layer;
A second member provided on a surface of the first member on the first conductive layer side and having a first electrode for detecting capacitance;
A third member provided on the second conductive layer side surface of the first member and having a second electrode for detecting capacitance;
The first member includes a weight portion disposed between the first electrode and the second electrode, a beam portion movably supporting the weight portion, connected to the beam portion, and the second member. A frame portion provided between the member and the third member,
The frame portion is used as a wiring for connecting the first electrode of the second member, and is electrically connected to the third member;
The capacitance type sensor, wherein the weight portion is electrically connected to the third member via the beam portion in a state of being electrically insulated from the frame portion. The first member includes a first silicon layer as the first conductive layer, a second silicon layer as the second conductive layer, and a SiO ₂ layer as the insulating layer. Item 14. A capacitive sensor according to Item 1.   3. The first conductive layer and the second conductive layer are electrically connected to each other by removing a part of the insulating layer along the outer surface in the frame portion. The capacitance type sensor described.   4. The capacitive sensor according to claim 1, wherein the third member has a drive electrode that applies simple vibration to the weight portion in order to measure angular velocity. 5.   The static electricity according to any one of claims 1 to 4, wherein the second electrode provided on the third member includes a plurality of electrodes for detecting a plurality of predetermined axial capacitances. Capacitive sensor.   6. The capacitance type according to claim 1, wherein the third member is formed of a semiconductor integrated circuit substrate having a signal processing function for processing the detected capacitance. Sensor. A method for manufacturing a capacitive sensor, comprising:
Using a first member having a first conductive layer, a second conductive layer, and an insulating layer formed between the first conductive layer and the second conductive layer, a weight portion and the weight Creating a beam part that movably supports the part and a frame part connected to the beam part;
Attaching a second member having a first electrode for detecting capacitance to a surface of the first member on the first conductive layer side;
For connection for electrically connecting the first conductive layer and the second conductive layer by removing a part of the insulating layer in each region of the frame portion and the weight portion of the first member Forming an electrode;
Attaching a third member having a second electrode for detecting capacitance to a surface of the first member on which the connection electrode is formed on the second conductive layer side, and
The frame portion is used as a wiring for connecting the first electrode of the second member, and is electrically connected to the third member;
The capacitance type sensor manufacturing method, wherein the weight portion is electrically connected to the third member in a state of being electrically insulated from the frame portion. The first member includes a first silicon layer as the first conductive layer, a second silicon layer as the second conductive layer, and a SiO ₂ layer as the insulating layer. Item 8. A method for producing a capacitive sensor according to Item 7.   9. The first conductive layer and the second conductive layer are electrically connected to each other by removing a part of the insulating layer along an outer surface in the frame portion. A manufacturing method of the described capacitive sensor.

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