JP5505340B2 - Mechanical quantity sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a mechanical quantity sensor that detects a mechanical quantity using an element whose resistance value changes according to an external force, and a method for manufacturing the same.

  In recent years, various electronic devices have been reduced in size, weight, functionality, and functionality, and electronic components to be mounted have been required to have higher density. In response to such demands, an increasing number of electronic components are manufactured as semiconductor devices. For this reason, in addition to the semiconductor device manufactured as a circuit element, a sensor for detecting a mechanical quantity is also manufactured using the semiconductor device, and a reduction in size and weight is achieved. For example, in an acceleration sensor having a small and simple structure formed by using MEMS (Micro Electro Mechanical Systems) technology, a movable part that is displaced according to an external force is formed on a semiconductor substrate, and the displacement of the movable part is measured by piezoelectricity. A sensor of a type that uses a resistance element, a capacitance element or the like for detection has been put into practical use.

  Conventionally, some contact-type semiconductor sensors detect the presence or absence of vibration or the like based on the presence or absence of contact between a movable electrode and a fixed electrode formed on a semiconductor substrate (see, for example, Patent Document 1). In addition, a ring-shaped movable electrode is formed on the outer peripheral portion of the structure wound in a spiral shape around the fixed portion on the semiconductor substrate, and the movable electrode, and the fixed electrode disposed around the movable electrode, In some cases, the inclination is detected by the presence or absence of contact (for example, see Non-Patent Document 1).

JP 2007-303974 A

Yashiro Nishioka, et al., "MEMS Tilt Sensor Fabricated Unifying Annotated Bonding of Thin Silicon Film on Glass Subs.", Electrology E, 129, 10p. 328-332

  However, in the contact-type semiconductor sensor proposed by the above-mentioned Patent Document 1 and Non-Patent Document 1, it is only possible to detect the presence or absence of contact between the movable electrode and the fixed electrode, and when the movable electrode and the fixed electrode are in contact with each other. Since the output level of the electric signal generated in the circuit is small, an amplifier circuit for amplifying the electric signal must be provided outside the sensor. Further, the direction of the detected external force is limited.

  Furthermore, conventional sensors that detect mechanical quantities using piezoresistive elements and capacitive semiconductor sensors have a problem in that the manufacturing process is complicated and the manufacturing cost increases.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a mechanical quantity sensor that can detect the magnitude and direction of external force and acceleration and can be manufactured at low cost, and a manufacturing method thereof. .

  A mechanical quantity sensor according to an embodiment of the present invention includes a first substrate, a fixing portion disposed on the first substrate, and one end portion supported by the fixing portion and spaced apart from the first substrate. A movable electrode, a fixed electrode positioned around the movable electrode and arranged in the detection direction of the mechanical quantity, a first terminal electrically connected to the fixed portion, and electrically connected to the fixed electrode And a second terminal. According to the mechanical quantity sensor according to the embodiment of the present invention, the magnitude and direction of the applied external force and the acceleration can be detected. Furthermore, since the structure can be simplified as compared with the conventional mechanical quantity sensor, a mechanical quantity sensor that is easy to manufacture can be realized.

  In the mechanical quantity sensor according to an embodiment of the present invention, the movable electrode is deformed by an applied external force to contact a part of the fixed electrode, and the fixed portion when the movable electrode contacts the fixed electrode. The magnitude of the external force may be detected based on a change in electrical resistance value between the electrode and the fixed electrode. According to the mechanical quantity sensor according to the embodiment of the present invention, a change in external force can be detected as a change in resistance value, so that the detection signal level can be increased as compared with a conventional mechanical quantity sensor. This eliminates the need for an amplifier circuit and can reduce the manufacturing cost.

  In the mechanical quantity sensor according to the embodiment of the present invention, the movable electrode may have a protrusion on the outermost side surface. According to the mechanical quantity sensor according to the embodiment of the present invention, due to the weight on the outer peripheral side of the movable electrode, it is easy to come into contact with the fixed electrode when an external force is applied. Also, it can be detected as a change in resistance value, and the detection sensitivity of external force can be improved.

  In the mechanical quantity sensor according to an embodiment of the present invention, the movable electrode may gradually increase in width as the movable electrode moves away from the fixed portion. According to the mechanical quantity sensor according to the embodiment of the present invention, due to the weight on the outer peripheral side of the movable electrode, it is easy to come into contact with the fixed electrode when an external force is applied. Also, it can be detected as a change in resistance value, and the detection sensitivity of external force can be improved.

  In the mechanical quantity sensor according to the embodiment of the present invention, the movable electrode may have a part of the innermost width wider than the outermost periphery. According to the mechanical quantity sensor according to the embodiment of the present invention, when an external force is applied due to a partial weight inside the movable electrode, the outer peripheral side easily comes into contact with the fixed electrode. Even if it is small, it can be detected as a change in resistance value, and the external force detection sensitivity can be improved.

  In the mechanical quantity sensor according to an embodiment of the present invention, the movable electrode includes a first movable electrode and a second movable electrode, and an outermost end portion of the first movable electrode is an inner ring-shaped movable electrode. The ring-shaped movable electrode is connected to a peripheral surface, and is disposed apart from the first substrate around the outermost periphery of the first movable electrode. The outer peripheral surface of the ring-shaped movable electrode has the first Two innermost ends of the movable electrode are connected, and the second movable electrode is spirally arranged on the outer periphery of the ring-shaped movable electrode and spaced from the first substrate, and the ring-shaped movable electrode The width may be larger than the widths of the first movable electrode and the second movable electrode. According to the mechanical quantity sensor according to the embodiment of the present invention, when the external force is applied due to the weight of the ring-shaped movable electrode, the second movable electrode easily comes into contact with the fixed electrode. Can be detected as a change in resistance value, and the external force detection sensitivity can be improved.

  In the mechanical quantity sensor according to an embodiment of the present invention, the movable electrode may be such that the interval between the spirals gradually decreases as the movable electrode moves away from the fixed portion. According to the mechanical quantity sensor according to the embodiment of the present invention, due to the weight on the outer peripheral side of the movable electrode, it is easy to come into contact with the fixed electrode when an external force is applied. Also, it can be detected as a change in resistance value, and the detection sensitivity of external force can be improved.

  In the mechanical quantity sensor according to an embodiment of the present invention, the fixed electrode may be arranged to face the movable electrode in a direction perpendicular to or parallel to the first substrate. The mechanical quantity sensor according to the embodiment of the present invention can detect the magnitude and direction of the external force in the three-axis directions (X direction, Y direction, and Z direction) and acceleration.

  The mechanical quantity sensor according to the embodiment of the present invention further includes a second substrate disposed on the fixed portion and the fixed electrode, and the second substrate is aligned with the positions of the fixed portion and the fixed electrode. You may have the electrode or wiring which is arrange | positioned and electrically connected to the said 1st terminal or the said 2nd terminal. According to the mechanical quantity sensor according to the embodiment of the present invention, the structure is simple as compared with the conventional mechanical quantity sensor. Therefore, the manufacturing process can be reduced and the manufacturing cost can be reduced.

  In the mechanical quantity sensor according to the embodiment of the invention, the fixed electrode may be arranged at a certain distance from the fixed portion. According to the mechanical quantity sensor according to the embodiment of the present invention, it is possible to reduce the difference in resistance value due to the difference in the contact position when the movable electrode contacts the fixed electrode.

  In the manufacturing method of the mechanical quantity sensor according to the embodiment of the present invention, the upper layer and the intermediate layer of the first substrate having three layers are etched, and the first portion is supported by the fixing portion and one end portion of the fixing portion. A spiral movable electrode separated from the substrate and a fixed electrode disposed around the movable electrode are formed, and an electrode or a position of the fixed portion and the fixed electrode is formed on the second substrate according to the formation position of the fixed portion and the fixed electrode. Forming a wiring, and joining the surface of the first substrate on which the fixed portion, the movable electrode, and the fixed electrode are formed, and the surface of the second substrate on which the electrode or the wiring is formed; May be included. According to the manufacturing method of the mechanical quantity sensor according to the embodiment of the present invention, the structure of the mechanical quantity sensor becomes simpler than that of the conventional manufacturing method of the mechanical quantity sensor. Cost can be reduced.

  In the manufacturing method of the mechanical quantity sensor according to the embodiment of the present invention, a recess is formed in a glass substrate by etching, an electrode or a wiring is formed on the surface of the glass substrate on which the recess is formed, and the electrode Alternatively, a semiconductor substrate is bonded onto the surface of the glass substrate on which the wiring is formed, and a surface of the semiconductor substrate on which the glass substrate is not bonded is etched, and a fixed portion and one end portion of the fixed portion are provided. The method may include forming a spiral movable electrode that is supported and separated from the glass substrate, and a fixed electrode that is disposed around the movable electrode. According to the manufacturing method of the mechanical quantity sensor according to the embodiment of the present invention, the structure of the mechanical quantity sensor becomes simpler than that of the conventional manufacturing method of the mechanical quantity sensor. Cost can be reduced.

  According to the present invention, by configuring the movable electrode and the fixed electrode so that the resistance value changes according to the magnitude of the external force, the magnitude of the external force can be detected, and the movable electrode deformed by the external force can be detected. The direction of the external force can be detected based on the contact position with the fixed electrode, and a mechanical quantity sensor that can be manufactured at low cost and a method for manufacturing the same can be provided.

1 is a plan view showing a schematic structure of a mechanical quantity sensor according to a first embodiment of the present invention. It is sectional drawing which looked at the mechanical quantity sensor shown to FIG. 1A from the AA 'line. It is a figure for demonstrating the manufacturing process of the mechanical quantity sensor which concerns on the 1st Embodiment of this invention, (A) is sectional drawing which shows the semiconductor substrate before a process, (B) forms a recessed part in a semiconductor substrate. Sectional drawing which shows a process, (C) is sectional drawing which shows the process of forming a fixed part, a movable electrode, and a fixed electrode in a semiconductor substrate. It is explanatory drawing of operation | movement of the mechanical quantity sensor which concerns on the 1st Embodiment of this invention, (a) shows the state in which the movable electrode contacted the fixed electrode when the external force F1 was applied, (b) is FIG. 4C shows a state in which the movable electrode is in contact with the fixed electrode when the external force F2 is applied, and FIG. 5C shows a state in which the movable electrode is in contact with the fixed electrode when the external force F3 is applied. It is a figure which shows typically the change of the length of the movable electrode corresponding to each operation state shown in FIG. 3, (a) is the length of the movable electrode corresponding to the operation state shown to Fig.3 (a). (B) illustrates the length of the movable electrode corresponding to the operating state shown in FIG. 3 (b), and (c) illustrates the movable corresponding to the operating state shown in FIG. 3 (c). The length of an electrode is illustrated. It is a figure for demonstrating the manufacturing process of the mechanical quantity sensor which concerns on the 2nd Embodiment of this invention, (A) is sectional drawing which shows the semiconductor substrate before a process, (B) forms a recessed part in a semiconductor substrate. Sectional drawing which shows a process, (C) is sectional drawing which shows the process of forming a fixed part, a movable electrode, and a fixed electrode in a semiconductor substrate. It is sectional drawing which showed the mechanical quantity sensor which concerns on the 2nd Embodiment of this invention. It is a top view which shows schematic structure when the 2nd semiconductor substrate of the mechanical quantity sensor which concerns on the 2nd Embodiment of this invention is seen from the upper surface. It is a top view which shows the modification of the 2nd semiconductor substrate of the mechanical quantity sensor which concerns on the 2nd Embodiment of this invention. It is sectional drawing which showed the mechanical quantity sensor which concerns on the 3rd Embodiment of this invention. It is a top view which shows schematic structure when the 2nd semiconductor substrate of the mechanical quantity sensor which concerns on the 3rd Embodiment of this invention is seen from the bottom face. It is a top view which shows the modification of the 2nd semiconductor substrate of the mechanical quantity sensor which concerns on the 3rd Embodiment of this invention. It is sectional drawing which showed the mechanical quantity sensor which concerns on the 4th Embodiment of this invention. It is a top view which shows schematic structure when the 2nd semiconductor substrate of the mechanical quantity sensor which concerns on the 4th Embodiment of this invention is seen from the bottom face. It is a figure for demonstrating the manufacturing process of the mechanical quantity sensor which concerns on the 5th Embodiment of this invention, (A) is sectional drawing which shows the glass substrate before a process, (B) forms a recessed part in a glass substrate. Sectional drawing which shows a process, (C) is sectional drawing which shows the process of forming the terminal for wiring in a glass substrate. It is a figure for demonstrating the manufacturing process of the mechanical quantity sensor which concerns on the 5th Embodiment of this invention, (A) is sectional drawing which shows the process of joining a semiconductor substrate to the glass substrate in which the terminal for wiring was formed, (B) is sectional drawing which shows the process of forming a fixed part, a movable electrode, and a fixed electrode in a semiconductor substrate. It is a top view which shows schematic structure when the glass substrate of the mechanical quantity sensor which concerns on the 5th Embodiment of this invention is seen from the upper surface. It is the top view which showed the modification of the mechanical quantity sensor which concerns on this invention. It is the top view which showed the modification of the mechanical quantity sensor which concerns on this invention. It is the top view which showed the modification of the mechanical quantity sensor which concerns on this invention. It is the top view which showed the modification of the mechanical quantity sensor which concerns on this invention. It is the top view which showed the modification of the mechanical quantity sensor which concerns on this invention. It is a figure which shows the circuit structure of the processing circuit which processes the signal detected by the dynamic quantity sensor which concerns on one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary, it can implement in various aspects.

(First embodiment)
<Structure of mechanical quantity sensor>
First, the basic structure of the mechanical quantity sensor according to the first embodiment of the present invention will be described with reference to FIGS. 1A and 1B. FIG. 1A is a plan view showing a schematic structure of a mechanical quantity sensor according to the first embodiment of the present invention. FIG. 1B is a cross-sectional view of the mechanical quantity sensor shown in FIG. 1A as viewed from the line AA ′. The mechanical quantity sensor 100 includes a semiconductor substrate 104, a fixed portion 101 formed on the semiconductor substrate 104, a movable electrode 102, and fixed electrodes 103a, 103b, 103c, and 103d. The fixing unit 101 is fixed on the semiconductor substrate 104. One end of the movable electrode 102 is connected to the fixed portion 101, and a plurality of spirally wound from the fixed portion 101 to the periphery is formed into a thin plate shape. The movable electrode 102 has flexibility and is deformed in the X direction, the Y direction, and the Z direction shown in the drawing in accordance with the applied external force. The structure of the movable electrode 102 is not limited to the shape shown in FIGS. 1A and 1B. For example, the winding interval is changed on the inner peripheral side and the outer peripheral side, or the width on the inner peripheral side and the outer peripheral side is changed. May be changed. The movable electrode 102 is a conductor having a predetermined resistivity ρ (Ω · cm), and has a resistance value R corresponding to a length L from one end connected to the fixed portion 101 to the other end on the outermost periphery. Have. Note that the resistivity ρ of the movable electrode 102 may be controlled by, for example, the concentration of impurities contained therein, and is 0.001 Ω · cm or more and 0.02 Ω · cm or less as a value measured by a four-probe measuring instrument. Also good. On the movable electrode 102, a metal film, gas diffusion, or ion implantation is used to form a Ti or Cr film of about 30 nm to 100 nm in the lower layer, and an Au film of about 100 nm to 300 nm is formed on the upper layer. The contact performance may be improved.

  The fixed electrodes 103a to 103d are located around the movable electrode 102 and arranged in the detection direction of the mechanical quantity. 1A and 1B show an example in which fixed electrodes 103a to 103d are arranged at four locations in the X direction and the Y direction. The number and arrangement position of the fixed electrodes are appropriately changed according to the specifications of the mechanical quantity sensor 100.

  The movable electrode 102 has a spiral structure deformed in accordance with the magnitude of the applied external force, and the fixed electrode 103a to 103d arranged in the direction in which the external force is applied is transferred to one of the spiral structures of the movable electrode 102. The parts touch. At this time, the length of the movable electrode 102 as a resistor is the length from one end connected to the fixed portion 101 to the contact portion, and the resistance value changes. The mechanical quantity sensor 100 detects the magnitude of the external force using a change in resistance value by the movable electrode 102.

  In order to electrically detect a change in resistance value due to the deformation of the movable electrode 102, a first terminal (not shown) is connected to the fixed portion 101, and a second terminal (not shown) is connected to each of the fixed electrodes 103a to 103d. Connected). The first terminal and the second terminal are connected to a circuit that processes a mechanical quantity detection signal in an electronic device in which the mechanical quantity sensor 100 is mounted.

  As shown in FIG. 1A, the movable electrode 102 may have an opening 102a at the outermost end of the spiral structure. The opening 102a may be configured such that the end portion of the movable electrode 102 is separated from the inner periphery one inner side from the outermost periphery by, for example, an interval equal to the spiral interval. The movable electrode 102 may have a shape that does not have the opening 102a, or may have a shape in which a terminal portion is joined to the inner periphery.

  In one embodiment of the present invention, the movable electrode 102 may be formed in a thin plate shape having a width of 15 μm and a height in the Z direction of 50 μm. The movable electrode 102 has a spiral structure of one or more rounds, and the interval between adjacent kth and k−1 weeks (where k> 1) may be 50 μm. In addition, the width | variety, thickness, and space | interval of a spiral of the movable electrode 102 do not need to be constant from the fixed part 101 to the terminal part of the outermost periphery. The fixed part 101 may have a cylindrical shape with a radius of 75 μm and a height in the Z direction of 50 μm. The fixed electrodes 103a to 103d may be formed in a thin plate shape having a length of 1190 μm, a width of 100 μm, and a thickness (height in the Z direction) of 50 μm, or may be disposed around the movable electrode 102. The distance from the fixed electrodes 103a to 103d to the fixed portion 101 may be 70 μm or may be constant. In the embodiment of the present invention, the dimensions of each part are appropriately changed according to the specifications.

<Method of manufacturing mechanical quantity sensor>
Next, a method for manufacturing the mechanical quantity sensor 100 according to the first embodiment will be described with reference to FIG. 2A and 2B are diagrams for explaining a manufacturing process showing a schematic structure of a cross section of the mechanical quantity sensor 100. FIG. 2A is a cross-sectional view showing a semiconductor substrate before processing, and FIG. Sectional drawing which shows the process of forming, (C) is sectional drawing which shows the process of forming a fixed part, a movable electrode, and a fixed electrode in a semiconductor substrate. 2C is a cross-sectional view of the mechanical quantity sensor shown in FIG. 1A as seen from the line AA ′, like FIG. 1B.

(1) Preparation of semiconductor substrate W (see FIG. 2A)
A semiconductor substrate (SOI substrate) W formed by laminating a silicon film 106, a BOX layer 105, and a silicon substrate 104 is prepared. The outer periphery of the silicon film 106, the BOX layer 105, and the silicon substrate 104 has a substantially square shape of 1.55 mm × 1.55 mm, for example, and the heights in the Z direction are 50 μm, 0.5 μm, and 400 μm, respectively. These external shapes and heights are examples, and are not limited to the above. The silicon film 106 is a layer constituting the fixed portion 101, the movable electrode 102, and the fixed electrodes 103a to 103d of the mechanical quantity sensor 100. The BOX layer 105 is a layer that joins the silicon film 106 and the silicon substrate 104 and functions as an etching stopper layer. The silicon substrate 104 constitutes the first semiconductor substrate 104 of the mechanical quantity sensor 100. The semiconductor substrate W is manufactured by SIMOX or a bonding method.

(2) Processing of the silicon film 106 (see FIG. 2B)
A mask (not shown) for processing the fixed portion 101, the movable electrode 102, and the fixed electrodes 103a to 103d is formed, and the silicon film 106 is etched through the mask, whereby the fixed portion 101 and the movable electrode 102 are processed. And the recess 106a except for the position where the fixed electrodes 103a to 103d are formed. As an etching method, DRIE (Deep Reactive Ion Etching) can be used.

(3) Processing of the BOX layer 105 (see FIG. 2C)
By side-etching the BOX layer 105, the BOX layer 105 in contact with the silicon film 106 at a position where the movable electrode 102 is formed is removed, and the movable electrode 102 separated from the first semiconductor substrate 104 is formed. FIG. 2C shows a shape in which the outer peripheral portion of the movable electrode 102 separated from the first semiconductor substrate 104 is lowered downward due to weight. As illustrated in FIG. 2C, the BOX layers 105 a to 105 e that are necessary only between the fixed portion 101 and the fixed electrodes 103 a to 103 d and the first semiconductor substrate 104 are left. As shown in FIG. 2B, the silicon film 106 corresponding to the position where the fixed portion 101 and the fixed electrodes 103a to 103d are formed has an area in contact with the BOX layer 105 so that the movable electrode 102 is formed. Since the area is larger than the area in contact with the BOX layer 105, the fixed portion 101 and the fixed electrodes 103 a to 103 d can be formed without being separated from the first semiconductor substrate 104 while leaving a part of the BOX layers 105 a to 105 e. it can. Examples of the etching method include wet etching using HF dilution (for example, diluting 50% HF to 10%) as an etching solution. In addition, the movable electrode 102 can be separated from the first semiconductor substrate 104 by dry etching.

  Through the above steps, the mechanical quantity sensor 100 according to the first embodiment of the present invention is formed.

<Operation of mechanical quantity sensor>
Next, the operation of the mechanical quantity sensor 100 according to the first embodiment will be described with reference to FIGS. 3 and 4. As described above, the mechanical quantity sensor 100 is configured such that one end portion of the movable electrode 102 is supported by the fixed portion 101 formed on the semiconductor substrate 104 and can be displaced in a space surrounded by the fixed electrodes 103a to 103d. Has been. The movable electrode 102 is deformed by an applied external force and contacts a part of the fixed electrodes 103a to 103d. The fixed part 101 and the fixed electrodes 103a to 103d are electrically connected to a first terminal and a second terminal (not shown). The resistance value changes depending on the length between the fixed end of the fixed portion 101 to which the movable electrode 102 is connected and the position where the movable electrode 102 is in contact with the fixed electrodes 103a to 103d. It is detected by a processing circuit connected to the terminal and the second terminal.

  Hereinafter, based on FIG.3 and FIG.4, the operation example of the dynamic quantity sensor 100 is demonstrated. FIG. 3 is an explanatory view of the operation of the mechanical quantity sensor according to the embodiment of the present invention, wherein (a) shows a state in which the movable electrode 102 is in contact with the fixed electrode 103b when the external force F1 is applied. (B) shows a state in which the movable electrode 102 is in contact with the fixed electrode 103b when an external force F2 larger than the external force F1 is applied, and (c) shows a state when an external force F3 larger than the external force F2 is applied. A state where the movable electrode 102 is in contact with the fixed electrode 103b is shown. FIG. 4 is a diagram schematically showing a change in the length L of the movable electrode 102 corresponding to each operation state shown in FIGS. 3A to 3C. FIG. (B) illustrates the length of the movable electrode corresponding to the operation state shown in FIG. 3B, and (c) illustrates the length of the movable electrode corresponding to the operation state shown in FIG. The length of the movable electrode corresponding to the operation state shown in c) is illustrated.

  As shown in FIG. 3A, when the external force F1 in the X direction is applied, the movable electrode 102 is deformed and comes into contact with the fixed electrode 103b in the outermost part B1, and is shown in FIG. 3B. As described above, when the external force F2 in the X direction is applied, the movable electrode 102 is deformed and comes into contact with the fixed electrode 103b in a part B2 of the inner circumference one inside from the outermost circumference, as shown in FIG. As shown in the figure, when the external force F3 in the X direction is applied, the movable electrode 102 is deformed and comes into contact with the fixed electrode 103b at a part B3 of the inner periphery two more inside than the outermost periphery. At this time, the external force F is F1 <F2 <F3. In FIG. 3, the fixed end where the movable electrode 102 is connected to the fixed portion 101 is indicated as A1, and the contact positions where the movable electrode 102 contacts the fixed electrode 103b are indicated as B1 to B3.

  As shown in FIG. 4A, when an external force F1 in the X direction is applied, the length of the movable electrode 102 from the fixed end A1 to the contact position B1 is L1, and as shown in FIG. When the external force F2 in the X direction is applied, the length of the movable electrode 102 from the fixed end A1 to the contact position B2 is L2, and the external force F3 in the X direction is applied as shown in FIG. In this case, the length of the movable electrode 102 from the fixed end A1 to the contact position B3 is L3. As shown in FIG. 4, the length L from the fixed end A1 to the contact positions B1 to B3 is L1> L2> L3. When the electric resistivity of the movable electrode 102 is ρ (Ω · cm), the electric resistance value R1 from the fixed end A1 to the contact position B1 shown in FIG. 4A is R1∝L1 · ρ. . Similarly, the electrical resistance value R2 from the fixed end A1 to the contact position B2 illustrated in FIG. 4B is R2∝L2 · ρ, and from the fixed end A1 to the contact position B3 illustrated in FIG. 4C. The electrical resistance value R3 of R3∝L3 · ρ. Therefore, as the applied external force F increases as F1 <F2 <F3, the electric resistance value R decreases as L1 · ρ> L2 · ρ> L3 · ρ, and the movable electrode 102 has a resistance corresponding to the magnitude of the external force. It can be seen that the resistance value R changes.

  Furthermore, when the mechanical quantity sensor 100 is used as an acceleration sensor, the displacement per time of the resistance value R of the movable electrode 102 caused by the action of acceleration may be detected. The acceleration in the X and Y axis directions can be detected by measuring the change in resistance value due to the displacement of the movable electrode 102 on the time axis.

  Further, the mechanical quantity sensor 100 can detect the direction of the external force by detecting whether the movable electrode 102 is in contact with any of the fixed electrodes 103a to 103d arranged around the movable electrode 102. For example, as illustrated in FIGS. 3A to 3C, when the movable electrode 102 is in contact with the fixed electrode 103 b, external forces F 1 to F 3 in the X direction are applied to the mechanical quantity sensor 100. I understand that. Further, by further increasing the number of fixed electrodes 103a to 103d, the resolution in the detection direction of the external force can be increased. For example, the number of fixed electrodes is increased to eight, and two fixed electrodes 101 are arranged on the top, bottom, left, and right (X and Y directions), so that the detection direction resolution for detecting the direction in which the external force is applied is improved. Can be increased. The number of fixed electrodes is not limited and can be changed as appropriate according to the required specifications.

  According to the mechanical quantity sensor 100 according to the first embodiment of the present invention, since a change in external force can be detected as a change in resistance value, a sensor of a type using a conventional piezoresistive element or a capacitance type sensor can be used. The detection signal level can be increased compared to the sensor. This eliminates the need for an amplifier circuit and can reduce manufacturing costs. In addition, the direction of the external force can be detected by arranging a plurality of fixed electrodes 103a to 103d around the movable electrode. Furthermore, since the structure can be simplified as compared with the conventional mechanical quantity sensor, a mechanical quantity sensor that is easy to manufacture can be realized.

(Second Embodiment)
<Method of manufacturing mechanical quantity sensor>
A method for manufacturing the mechanical quantity sensor 200 according to the second embodiment will be described with reference to FIGS. FIGS. 5A to 5C and FIG. 6 are diagrams for explaining a manufacturing process showing a schematic structure of a cross section of the mechanical quantity sensor 200, and FIG. 2 is a plan view showing a schematic structure when a semiconductor substrate 207 is viewed from above. FIG. 6 shows a cross section of the mechanical quantity sensor 200 shown in FIG. 7 as seen from the line BB ′.

(1) Preparation of semiconductor substrate W (see FIG. 5A)
A semiconductor substrate (SOI substrate) W formed by laminating a silicon film 206, a BOX layer 205, and a silicon substrate 204 is prepared. The outer periphery of the silicon film 206, the BOX layer 205, and the silicon substrate 204 has a substantially square shape of 1.55 mm × 1.55 mm, for example, and the heights in the Z direction are 50 μm, 0.5 μm, and 400 μm, respectively. These external shapes and heights are examples, and are not limited to the above. The silicon film 206 is a layer constituting the fixed portion 201, the movable electrode 202, and the fixed electrodes 203a to 203h of the mechanical quantity sensor 200. The BOX layer 205 is a layer that joins the silicon film 206 and the silicon substrate 204 and functions as an etching stopper layer. The silicon substrate 204 constitutes the first semiconductor substrate 204 of the mechanical quantity sensor 200. The semiconductor substrate W is manufactured by SIMOX or a bonding method.

(2) Processing of the silicon film 206 (see FIG. 5B)
A mask (not shown) for processing the fixed portion 201, the movable electrode 202, and the fixed electrodes 203a to 203h is formed, and the silicon film 206 is etched through the mask, whereby the fixed portion 201 and the movable electrode 202 are etched. , And a recess 206a excluding the position where the fixed electrodes 203a to 203h are formed. As an etching method, DRIE (Deep Reactive Ion Etching) can be used.

(3) Processing of the BOX layer 205 (see FIG. 5C)
By side-etching the BOX layer 205, the BOX layer 205 in contact with the silicon film 206 at the position where the movable electrode 202 is formed is removed, and the movable electrode 202 separated from the first semiconductor substrate 204 is formed. At this time, necessary BOX layers 205a to 205i (see FIG. 6) are left only between the fixed portion 201 and the fixed electrodes 203a to 203h and the first semiconductor substrate 204. As shown in FIG. 5B, the silicon film 206 corresponding to the position where the fixed portion 201 and the fixed electrodes 203a to 203h are formed has an area in contact with the BOX layer 205 so that the movable electrode 202 is formed. Since the area is larger than the area in contact with the BOX layer 205, the fixed portion 201 and the fixed electrodes 203 a to 203 h can be formed without being separated from the first semiconductor substrate 204 while leaving a part of the BOX layers 205 a to 205 i. it can. As an etching method, wet etching using HF dilution (for example, diluting 50% HF to 10%) as an etchant can be given. Further, dry etching by the RIE method using a mixed gas of CF ₄ gas and O ₂ gas is also applicable.

(4) Formation of the second semiconductor substrate 207 (see FIGS. 6 and 7)
The second semiconductor substrate 207 illustrated in FIGS. 6 and 7 is made of any one of a glass material, a semiconductor, a metal material, and an insulating resin material. Hereinafter, a case where a glass material is used as the second semiconductor substrate 207 will be described. You may use the glass substrate (for example, Tempax (trademark) glass) containing a movable ion. As shown in FIG. 6, a recess 207a is formed in the second semiconductor substrate 207 by etching or sandblasting so as to correspond to the position facing the movable electrode 202 of the first semiconductor substrate 204.

(5) Formation of through electrodes 208a to 208i (see FIGS. 6 and 7)
In the second semiconductor substrate 207, through electrodes 208a to 208i penetrating vertically are formed as shown in FIG. The through electrodes 208a to 208i are electrically connected to the fixed portion 201 and the fixed electrodes 203a to 203h of the first semiconductor substrate 204 when the first semiconductor substrate 204 and the second semiconductor substrate 207 are bonded in a manufacturing process described later. Are formed at positions facing the fixed portion 201 and the fixed electrodes 203a to 203h, respectively. Through holes (not shown) are formed in the respective formation positions of the through electrodes 208a to 208i by sand blasting the second semiconductor substrate 207 on which a predetermined mask is formed. Through electrodes 208a to 208i are formed by disposing a conductive material having conductivity using a conductive paste filling (screen printing), a CVD (Chemical Vapor Deposition) method, an electrolytic plating method, or the like inside the through hole. To do. For example, the through electrodes 208a to 208i may be formed by depositing a conductive layer made of polycrystalline silicon (Poly-Si) on the inner wall of the through hole by a CVD method. As the conductive layer, for example, a metal material (Ti, Cu, etc.) may be used in addition to polycrystalline silicon.

(6) Bonding of the first semiconductor substrate 204 and the second semiconductor substrate 207 (see FIG. 6)
The first semiconductor substrate 204 and the second semiconductor substrate 207 are bonded by anodic bonding or the like. At this time, as illustrated in FIG. 6, the through electrodes 208 a to 208 i formed on the second semiconductor substrate 207 and the fixed portion 201 and the fixed electrodes 203 a to 203 h formed on the first semiconductor substrate 204 are electrically connected to each other. To be connected to each other. In addition, the concave portion 207 a formed in the second semiconductor substrate 207 and the movable electrode 202 formed in the first semiconductor substrate 204 are joined at a position facing each other. As shown in FIG. 6, the distances d1 from the end portions of the fixed electrodes 203a to 203h to which the movable electrode 202 is in contact to the connection portions of the through electrodes 208a to 208h are the same distance. The fixed electrodes 203a to 203h are arranged at a fixed distance d2 from the fixed portion 201. Thereby, the difference in resistance value due to the difference in the contact position when the movable electrode 202 contacts the fixed electrodes 203a to 203h can be reduced.

(7) Formation of wiring terminals 208a ′ to 208i ′ (see FIGS. 6 and 7)
FIG. 7 is a plan view showing an example of the upper surface of the second semiconductor substrate 207 shown in FIG. As shown in FIGS. 6 and 7, wiring terminals 208 a ′ to 208 i ′ are formed on the upper surface of the second semiconductor substrate 207 so as to correspond to the upper surface portions from which the through electrodes 208 a to 208 i are exposed. For example, a pattern made of Al may be formed so as to be electrically connected to 208i. These wiring terminals 208 a ′ to 208 i ′ are connected to a circuit that processes a mechanical quantity detection signal in an electronic device in which the mechanical quantity sensor 200 is mounted. Note that the through electrode 208i and the wiring terminal 208i ′ connected to the fixed portion 201 function as the first terminal described above, and the through electrodes 208a to 208h and the wiring terminals 208a ′ to 208h connected to the fixed electrodes 203a to 203h. 'Functions as the second terminal described above. The wiring terminals 208 a ′ to 208 i ′ may be formed on the second semiconductor substrate 207 before bonding the first semiconductor substrate 204 and the second semiconductor substrate 207.

  Through the above steps, the mechanical quantity sensor 200 according to the second embodiment of the present invention is formed.

  Note that the mechanical quantity sensor 200 according to the second embodiment of the present invention is not limited to the configuration of the second semiconductor substrate 207 illustrated in FIG. 7, and may be configured as illustrated in FIG. 8, for example. .

  FIG. 8 illustrates another embodiment of the second semiconductor substrate 207, and is a plan view of the second semiconductor substrate 207 on which wiring terminals 208a ′ to 208i ′ are formed as viewed from above. As shown in FIG. 8, wiring terminals connected to wiring terminals 208 a ′ to 208 i ′ near one end of the upper surface of the second semiconductor substrate 207 (the right side of the second semiconductor substrate 207 in the drawing). 208a ″ to 208i ″ may be formed. For the wiring terminals 208a ′ to 208i ′ and 208a ″ to 208i ″, for example, a metal layer is formed in the order of Cr layer and Au layer by vapor deposition or sputtering, and unnecessary metal layers are etched. It may be formed by removing.

  According to the mechanical quantity sensor 200 according to the second embodiment of the present invention, the movable electrode 202 is displaced by an applied external force, and a part of the movable electrode 202 is moved to any one of the fixed electrodes 203a to 203h arranged around. Touch. At this time, the length of the movable electrode 202 as a resistor is the length from one end connected to the fixed portion 201 to the contact portion, and the resistance value changes according to the magnitude of the applied external force. The magnitude of the external force can be detected by detecting a detection signal corresponding to the change in the resistance value by a processing circuit connected to the mechanical quantity sensor 200. Further, the mechanical quantity sensor 200 according to the second embodiment of the present invention has a simple structure as compared with a sensor of a type using a conventional piezoresistive element or a capacitive sensor. Therefore, the manufacturing process can be reduced and the manufacturing cost can be reduced.

(Third embodiment)
<Method of manufacturing mechanical quantity sensor>
Next, with reference to FIG.9 and FIG.10, the manufacturing method of the dynamic quantity sensor 300 which concerns on the 3rd Embodiment of this invention is demonstrated. FIG. 9 shows a schematic structure of a cross section of the mechanical quantity sensor 300, and FIG. 10 shows a schematic structure when the second semiconductor substrate 307 of the mechanical quantity sensor 300 is viewed from the bottom. FIG. 9 shows a cross section of the mechanical quantity sensor 300 shown in FIG. 10 as seen from the line CC ′.

  As illustrated in FIG. 9, the mechanical quantity sensor 300 according to the third embodiment of the present invention is formed on the first semiconductor substrate 304 in the same process as the manufacturing process illustrated in FIGS. After that, a fixed portion 301, a movable electrode 302, and fixed electrodes 303a to 303h are formed. Further, through the same manufacturing process as the fixed electrodes 303a to 303h, a fixed portion electrode 303j that is electrically connected to the fixed portion 301 is formed.

  As the second semiconductor substrate 307, a glass substrate may be used in the same manner as the second semiconductor substrate 207 of the mechanical quantity sensor 200 shown in FIG. In the second semiconductor substrate 307, a recess 307a is formed by etching or sandblasting so as to correspond to the position facing the movable electrode 302 of the first semiconductor substrate 304.

  On the surface (the lower surface in FIG. 9) of the second semiconductor substrate 307 in which the recess 307a is formed, the insulating layer 308 is formed by patterning in accordance with the formation positions of the electrodes 309a to 309i shown in FIG. Electrodes 309a to 309i are formed on the insulating layer 308. The electrodes 309a to 309i are electrically connected to the fixed portion 301 and the fixed electrodes 303a to 303h of the first semiconductor substrate 304, respectively, and function as the first terminal and the second terminal described above, and thus the fixed portion 301 and the fixed electrode 303a. It is formed by patterning each at a position opposite to ˜303h.

  The insulating layer 308 is made of an inorganic insulating layer such as silicon oxide or silicon nitride, for example. In the case of silicon oxide, it may be formed using a thermal oxidation method or a CVD (Chemical Vapor Deposition) method. In the case of silicon nitride, it may be formed using a CVD method. The electrodes 309a to 309i are made of a material such as metal or polycrystalline silicon, and the material can be appropriately selected depending on the materials of the first semiconductor substrate 304 and the second semiconductor substrate 307 to be bonded, the bonding method, and the like.

  Since the entire size of the second semiconductor substrate 307 is smaller than the entire size of the first semiconductor substrate 304, when the second semiconductor substrate 307 is bonded to the first semiconductor substrate 304, the outer circumference of the first semiconductor substrate 304 is increased. Bonded to expose the area. At this time, the second semiconductor substrate 307 is bonded so as to expose part of the fixed electrodes 303a to 303h and the fixed portion electrode 303j near the end portions formed on the first semiconductor substrate 304.

  When the first semiconductor substrate 304 and the second semiconductor substrate 307 are joined, the fixed portion 301 and the fixed electrodes 303a to 303h formed on the first semiconductor substrate 304 are respectively connected to the electrodes 309a to 309i of the second semiconductor substrate 207. Electrically connected. As shown in FIG. 9, the distances d1 from the end portions of the fixed electrodes 303a to 303h with which the movable electrode 302 is brought into contact to the connection portions of the electrodes 309a to 309h are the same distance. Further, the fixed electrodes 303a to 303h are arranged at a fixed distance d2 from the fixed portion 301. Thereby, the difference in resistance value due to the difference in the contact position when the movable electrode 302 contacts the fixed electrodes 303a to 303h can be reduced.

  FIG. 10 is a plan view of the second semiconductor substrate 307 formed with the electrodes 309a to 309i of the mechanical quantity sensor 300 as viewed from the bottom. In FIG. 10, when the first semiconductor substrate 304 is bonded, the positions where the first semiconductor substrate 304, the fixed electrodes 303a to 303h, and the fixed portion 301 are arranged are indicated by dotted lines. Although not shown, an insulating layer 308 is formed between the electrodes 309 a to 309 i and the second semiconductor substrate 307.

  As shown in FIG. 10, the electrode 309 i that is electrically connected to the fixed portion 301 is electrically connected to the fixed portion electrode 303 j formed on the first semiconductor substrate 304. Although not shown, wirings are connected to regions of the fixed electrodes 303a to 303h and the fixed portion electrode 303j that are exposed outside the second semiconductor substrate 307 by a method such as wire bonding. These wirings are connected to a circuit that processes a mechanical quantity detection signal in an electronic device in which the mechanical quantity sensor 300 is mounted.

  Through the above steps, the mechanical quantity sensor 300 according to the third embodiment of the present invention is formed.

  Note that the mechanical quantity sensor 300 according to the third embodiment of the present invention is not limited to the configuration of the second semiconductor substrate 307 illustrated in FIG. 10, and may be configured as illustrated in FIG. 11, for example. .

  FIG. 11 illustrates another embodiment of the second semiconductor substrate 307, and is a plan view of the second semiconductor substrate 307 on which the electrodes 309a to 309i are formed as viewed from the bottom. FIG. 11 shows an example in which dummy terminals 310j are formed in the outer peripheral region of the second semiconductor substrate 307 so as to achieve a balance when bonded to the first semiconductor substrate 304.

  As shown in FIG. 11, wiring patterns 309 a ′ to 309 i ′ to which the electrodes 309 a to 309 i are electrically connected are formed on the second semiconductor substrate 307, and near one side end of the first semiconductor substrate 304 ( It may be formed so as to be connected to wiring terminals 310a to 310i formed on the right side of the first semiconductor substrate 304 in the drawing. In FIG. 11, when the first semiconductor substrate 304 is bonded, the first semiconductor substrate 304, the fixed electrodes 303a to 303h, the fixed portion 301, the wiring terminals 310a to 310i, and the plurality of dummy terminals 310j are arranged. The position to be performed is indicated by a dotted line. Although not shown, an insulating layer is formed between the electrodes 309 a to 309 i and the wiring patterns 309 a ′ to 309 i and the second semiconductor substrate 307.

  The dummy terminal 310j is formed in the vicinity of the end portion of the outer peripheral region of the first semiconductor substrate 304 excluding the vicinity of one end portion where the wiring terminals 310a to 310i are formed. When the first semiconductor substrate 304 and the second semiconductor substrate 307 are bonded, the dummy terminal 310j is stably bonded by the wiring terminals 310a to 310i formed only at one end of the first semiconductor substrate 304. In other words, the entire outer periphery of the first semiconductor substrate 304 and the entire outer periphery of the second semiconductor substrate 307 are bonded to each other. For this reason, the shape of each dummy terminal 310j is desirably the same as that of each of the wiring terminals 310a to 310i. The second semiconductor substrate 307 illustrated in FIG. 11 overlaps with a part of the wiring terminals 310a to 310i and is joined so as to expose a part. Although not shown, the regions exposed to the outside of the second semiconductor substrate 307 of the wiring terminals 310a to 310i may be connected to an external circuit by wire bonding or the like.

  The mechanical quantity sensor 300 according to the third embodiment of the present invention manufactured through the above steps is an external force in the biaxial direction (X direction, Y direction), similarly to the mechanical quantity sensor 200 according to the second embodiment. Can be detected. In addition, the structure is simple compared to a conventional sensor using a piezoresistive element or a capacitive sensor. Therefore, the manufacturing process can be reduced and the manufacturing cost can be reduced.

(Fourth embodiment)
<Method of manufacturing mechanical quantity sensor>
Furthermore, with reference to FIG. 12 and FIG. 13, the configuration and manufacturing method of the mechanical quantity sensor 400 capable of detecting the magnitude and direction of external force in the three-axis directions (X direction, Y direction, and Z direction) and acceleration. State.

  FIG. 12 is a cross-sectional view showing a mechanical quantity sensor 400 according to the fourth embodiment of the present invention. FIG. 13 is a plan view of the second semiconductor substrate 407 of the mechanical quantity sensor 400 shown in FIG. 12 as viewed from the bottom. FIG. 12 shows a cross section of the mechanical quantity sensor 400 shown in FIG. 13 as seen from the line DD ′.

  The mechanical quantity sensor 400 is subjected to the same manufacturing process as the mechanical quantity sensor 300 according to the third embodiment, and the first semiconductor substrate 404 is fixed to the fixed portion 401, the movable electrode 402, the fixed electrodes 403a to 403h, and the fixed portion electrode. 403j is formed, and a recess 407a, an insulating layer 408, and electrodes 409a to 409i are formed in the second semiconductor substrate 407.

  Further, unlike the mechanical quantity sensor 300 according to the third embodiment, the mechanical quantity sensor 400 has a fixed electrode 403a on the second semiconductor substrate 407 in order to detect the magnitude and direction of the external force in the Z direction and acceleration. The electrode 409k having the same function as ˜403h is formed through the same manufacturing process as the electrodes 409a to 409i. In addition, a fixed electrode 403k electrically connected to the electrode 409k is formed on the first semiconductor substrate 404 through the same manufacturing process as the fixed electrodes 403a to 403h.

  The electrode 409k is formed in the concave portion 407a of the second semiconductor substrate 407 at a position facing the movable electrode 402, and is disposed at a position where the movable electrode 402 deformed by an external force in the Z direction comes into contact. As shown in FIG. 12, an insulating layer 408 is formed in the recess 407a of the second semiconductor substrate 407 by patterning in accordance with the formation position of the electrode 409k, and the electrode 409k is patterned on the insulating layer 408. Is formed. 12 and 13 show only one electrode 409k for detecting an external force in the Z direction, but the present invention is not limited to this, and a plurality of electrodes may be formed according to specifications. By disposing a plurality of fixed electrodes 409k according to the detection direction, it is possible to increase the detection direction resolution of the external force in the Z direction.

  Similarly to the mechanical quantity sensors 200 and 300 according to the first and third embodiments illustrated in FIG. 12, each end part of the fixed electrodes 403 a to 403 h with which the movable electrode 402 is contacted also in the mechanical quantity sensor 400. The distances d1 from the connecting portions of the electrodes 409a to 409h to the connecting portions are the same. Further, the fixed electrodes 403a to 403h are arranged at a fixed distance d2 from the fixed portion 401. Thereby, the difference in resistance value due to the difference in the contact position when the movable electrode 402 contacts the fixed electrodes 403a to 403h can be reduced.

  The portions of the fixed electrodes 403a to 403h and 403k and the fixed portion electrode 403j that are exposed outside the second semiconductor substrate 407 may be connected to an external circuit that processes the mechanical quantity detection signal by wire bonding or the like. Accordingly, the mechanical quantity sensor 400 can detect a change in resistance value when the movable electrode 102 is brought into contact with the electrode 409k by applying an external force in the Z direction. It becomes possible to detect.

  According to the mechanical quantity sensor 400 according to the fourth embodiment of the present invention manufactured through the above steps, the magnitude and direction of the external force in the three axial directions (X direction, Y direction, Z direction) and acceleration are detected. be able to. In addition, the structure is simple compared to a conventional sensor using a piezoresistive element or a capacitive sensor. Therefore, the manufacturing process can be reduced and the manufacturing cost can be reduced.

(Fifth embodiment)
<Method of manufacturing mechanical quantity sensor>
Hereinafter, with reference to FIGS. 14-16, the manufacturing method of the dynamic quantity sensor 500 which concerns on the 5th Embodiment of this invention is demonstrated. FIGS. 14A to 14C and FIGS. 15A and 15B are diagrams for explaining a manufacturing process showing a schematic structure of a cross section of the mechanical quantity sensor 500, and FIG. It is a top view which shows schematic structure when the glass substrate 504 of the sensor 500 is seen from the upper surface. FIG. 15B shows a cross section of the mechanical quantity sensor 500 shown in FIG. 16 as seen from the line EE ′.

(1) Formation of glass substrate 504 (see FIGS. 14A and 14B)
As the glass substrate 504, a glass substrate containing movable ions (for example, Tempax (registered trademark) glass) may be used. As shown in FIG. 14B, a recess 504a is formed in the glass substrate 504 by etching or sandblasting. The concave portion 504a is formed corresponding to the position where the movable electrode 502 formed on the semiconductor substrate 506 bonded to the glass substrate 504 is formed in a process described later.

(2) Formation of wiring terminals 505a to 505e and 505a ′ to 505e ′ (see FIG. 14C and FIG. 16)
Wiring terminals 505a to 505e and 505a ′ to 505e ′ are formed on the surface of the glass substrate 504 on the side where the recesses 504a are formed, as shown in FIGS. The wiring terminals 505a to 505e and 505a ′ to 505e ′ may be formed by, for example, forming a metal layer in the order of Cr layer and Au layer by vapor deposition or sputtering, and removing unnecessary metal layers by etching. Good. The wiring terminals 505a to 505e are electrically connected to the fixed portion 501 and the fixed electrodes 503a to 503d formed on the semiconductor substrate 506, respectively, when the glass substrate 504 and the semiconductor substrate 506 are bonded in a process described later. In this way, it is formed at a position facing the fixed portion 501 and the fixed electrodes 503a to 503d. The wiring terminals 505a ′ to 505e ′ are connected to the wiring terminals 505a to 505e, and as shown in FIG. 16, in the vicinity of one end on the surface of the glass substrate 504 on the side where the recesses 504a are formed (see FIG. It may be formed on the upper side of the glass substrate 504 inside.

(3) Bonding between the glass substrate 504 and the semiconductor substrate 506 (see FIG. 15A)
The glass substrate 504 and the semiconductor substrate 506 are bonded by anodic bonding or the like. The semiconductor substrate 506 is a semiconductor substrate in which impurities are diffused so as to have a desired resistivity. As shown in FIG. 15A, the semiconductor substrate 506 is bonded onto the surface of the glass substrate 504 on the side where the wiring terminals 505a to 505e and 505a ′ to 505e ′ are formed.

(4) Processing of semiconductor substrate 506 (see FIG. 15B)
A mask (not shown) for processing the fixed portion 501, the movable electrode 502, and the fixed electrodes 503a to 503d is formed, and the semiconductor substrate 506 is etched through the mask, whereby the fixed portion 501 and the movable electrode 502 are etched. , And a recess 506a excluding the position where the fixed electrodes 503a to 503d are formed. Thereby, on the glass substrate 504, the fixed part 501, the movable electrode 502, and the fixed electrodes 503a to 503d electrically connected to the wiring terminals 505a to 505e are formed. As an etching method, DRIE (Deep Reactive Ion Etching) can be used.

  According to the mechanical quantity sensor 500 according to the fifth embodiment of the present invention manufactured through the above steps, the biaxial direction (X) as in the mechanical quantity sensors 200 and 300 according to the first and third embodiments. Direction, Y direction) can be detected. In addition, the structure is simple compared to a conventional sensor using a piezoresistive element or a capacitive sensor. Therefore, the manufacturing process can be reduced and the manufacturing cost can be reduced.

  As described above, the mechanical quantity sensors 200 to 500 according to the first to fifth embodiments of the present invention are formed by a conventional etching method or patterning method using a substrate having two or three layers. The manufacturing process is simplified. Thereby, it becomes possible to manufacture the mechanical quantity sensors 200 to 500 at a low cost without increasing the manufacturing cost.

(Modification)
Next, modified examples of the mechanical quantity sensor will be described below with reference to FIGS. 17 to 21 are plan views showing a schematic structure of mechanical quantity sensors 600 to 1000 according to an embodiment of the present invention.

  As illustrated in FIG. 17, the mechanical quantity sensor 600 may be formed such that the interval between the spirals on the inner peripheral side of the movable electrode 602 is wide and the interval between the spirals on the outer peripheral side of the movable electrode 602 is narrow. As a result, when an external force is applied, it becomes easy to come into contact with the fixed electrodes 603a to 603d due to the weight on the outer peripheral side of the movable electrode 602. Therefore, even when the applied external force is small, the resistance value changes. It can be detected, and the detection sensitivity of external force can be improved.

  In addition, as illustrated in FIG. 18, the mechanical quantity sensor 700 may form protrusions 702 a to 702 d at positions on the outermost periphery of the movable electrode 702 facing the fixed electrodes 703 a to 703 d. The protrusions 702a to 702d are formed as part of the movable electrode 702, and are formed by etching the same semiconductor substrate in the same manufacturing process as the manufacturing process of the movable electrode 702. By having the protrusions 702a to 702d, when an external force is applied, the movable electrode 702 is weighted on the outer peripheral side, and the protrusions 702a to 702d easily come into contact with the fixed electrodes 703a to 703d. Detection sensitivity can be improved. In addition, in FIG. 18, although the rectangular-shaped protrusion parts 702a-702d are illustrated, it is not limited to this shape, A circular shape or a triangular shape may be sufficient. The thicknesses of the protrusions 702a to 702d are also changed as appropriate according to the specifications. Further, the number of the protrusions 702a to 702d is not limited to the number illustrated in FIG. 18, and the resolution with respect to the direction of the external force can be improved by arranging a plurality of protrusions 702a to 702d corresponding to the fixed electrodes 703a to 703d. Therefore, it is appropriately changed according to the specification.

  Furthermore, as illustrated in FIG. 19, the mechanical quantity sensor 800 may be formed such that the width of the movable electrode 802 increases as it winds from the inner periphery to the outer periphery. FIG. 19 illustrates a shape in which the width gradually increases from the outermost periphery of the movable electrode 802 toward the outer periphery from the inner portion of the third periphery. By forming the width of the movable electrode 802 so as to be closer to the outer periphery, when an external force is applied, it becomes easier to come into contact with the fixed electrodes 803a to 803d due to the weight on the outer peripheral side of the movable electrode 802. Even if it is small, it can be detected as a change in resistance value, and the external force detection sensitivity can be improved.

  Further, as illustrated in FIG. 20, the mechanical quantity sensor 900 may be formed such that the width of the movable electrode 902 is the largest on the inner circumference inside the outermost circumference. For example, as shown in FIG. 20, by forming the innermost part of the movable electrode 902 from the outermost periphery to the innermost part of the circumference, the movable electrode 902 from the outermost periphery to the innermost part of the outer periphery is formed into three parts. It becomes easy to contact the fixed electrodes 903a to 903d due to the weight of the inner portion of the circumference. Thereby, even if the applied external force is small, it can be detected as a change in resistance value. In addition, since a plurality of winding portions outside the portion with the largest width can easily come into contact with the fixed electrodes 903a to 903d, a change in resistance value with respect to an external force can be increased. Therefore, the external force detection sensitivity can be improved. Note that FIG. 20 illustrates a structure in which the width of the innermost part of the three circumferences from the outermost circumference is the largest. However, the shape is not limited to this shape, and the movable electrode 902 has a width on the inner side of the outermost circumference. You may have two or more big places.

  Further, as illustrated in FIG. 21, the mechanical quantity sensor 1000 may include a ring-shaped movable electrode 1002 r on the inner side of the outermost periphery of the movable electrode 1002. For example, as shown in FIG. 21, the movable electrode 1002 includes a first movable electrode 1002a connected to the inner peripheral surface of the ring-shaped movable electrode 1002r and a first electrode connected to the outer peripheral surface of the ring-shaped movable electrode 1002r. A ring-shaped movable electrode 1002r having a width larger than the width of each of the first movable electrode 1002a and the second movable electrode 1002b, on the inner side of the third circumference from the outermost periphery of the movable electrode 1002. May be. The first movable electrode 1002a, the ring-shaped movable electrode 1002r, and the second movable electrode 1002b are spaced apart from the first substrate 1004, respectively, and the first movable electrode 1002a and the second movable electrode 1002b are ring-shaped movable. The electrodes 1002r are respectively arranged in a spiral shape on the inner side and the outer side.

  Each of the first movable electrode 1002a, the ring-shaped movable electrode 1002r, and the second movable electrode 1002b may have a height in the Z direction of 50 μm. The width of the first movable electrode 1002a and the second movable electrode 1002b may be 15 μm, for example, and the width of the ring-shaped movable electrode 1002r may be 100 μm, for example. By making the width of the ring-shaped movable electrode 1002r larger than the width of the first movable electrode 1002a and the second movable electrode 1002b, the second movable electrode 1002b disposed outside the ring-shaped movable electrode 1002r is fixed to the fixed electrode 1003a. It becomes easy to contact with 1003d. Further, the spiral interval of the first movable electrode 1002a may be 50 μm, and the spiral interval of the second movable electrode 1002b may be 15 μm. By making the interval between the second movable electrodes 1002b arranged outside the ring-shaped movable electrode 1002r smaller than the interval between the first movable electrodes 1002a arranged inside, the second movable electrode 1002b is fixed to the fixed electrodes 1003a to 1003a. It becomes easy to contact 1003d. With such a configuration, like the mechanical quantity sensor 900 shown in FIG. 20, the mechanical quantity sensor 1000 shown in FIG. 21 can detect a change in resistance value even when the applied external force is small. The change of the resistance value with respect to the external force can be increased. Therefore, the external force detection sensitivity can be improved. FIG. 21 illustrates the shape having the ring-shaped movable electrode 1002r on the inner side of the outer periphery three times. However, the shape is not limited to this shape, and a plurality of ring-shaped movable electrodes 1002r are provided on the inner side of the outermost periphery. It may be a shape.

  As described above, the mechanical quantity sensors 600 to 1000 according to the embodiment of the present invention can increase the external force detection sensitivity by changing the shapes of the movable electrodes 602 to 1002.

  Next, a configuration example of the processing circuit 1110 that processes each mechanical quantity detection signal detected by the mechanical quantity sensors 100 to 1100 will be described with reference to FIG.

<Processing circuit>
FIG. 22 is a diagram illustrating a circuit configuration of the processing circuit 1110. In FIG. 22, the processing circuit 1110 includes a filter circuit 1101. A mechanical quantity sensor 1100 is connected to the input stage of the filter circuit 1101.

  As shown in FIG. 22, the mechanical quantity sensor 1100 has one end connected to the power supply voltage Vcc and the other end grounded. The mechanical quantity sensor 1100 is shown as a variable resistance circuit. The filter circuit 1101 is connected to the power supply voltages Vcc and GND, and a detection line Ls for detecting the variable resistance value of the mechanical quantity sensor 1100 is connected to the input stage.

  The mechanical quantity sensor 1100 changes the detection voltage Vs between the detection lines Ls and GND when the resistance value changes according to the magnitude of the applied external force, and the detection signal corresponding to the detection voltage Vs is converted into a filter circuit. 1101 is input. The filter circuit 1101 removes the noise component of the detection signal and outputs it as a detection output signal Vout to the outside.

  Note that the detection signal output from the processing circuit 1110 is a signal whose voltage value changes in accordance with the magnitude of the applied external force. Therefore, a memory for storing the voltage value of the detection signal output from the processing circuit 1110 and the value of the external force in association with each other is prepared, and a value indicating the magnitude of the external force corresponding to the detection signal is prepared from this memory. You may make it output.

  As illustrated in FIG. 22, according to the mechanical quantity sensor 1100 according to the embodiment of the present invention, it is not necessary to use an amplifier circuit or the like. Therefore, the peripheral circuit can be simplified. Thereby, since a space is created when the mechanical quantity sensor 1100 is mounted on the electronic device, the space can be effectively utilized. In addition, the manufacturing cost of the processing circuit 1110 can be reduced.

  The above-described mechanical quantity sensors 100 to 1100 according to the embodiments of the present invention are mounted on a circuit board on which an active element such as an IC is mounted, for example, and are connected to the wiring terminals by a known method and material such as wire bonding connection. By connecting an active element such as an electronic circuit board or IC, the mechanical quantity sensor and the electronic circuit can be provided as one electronic component. This electronic component can be distributed in the market by being mounted on a mobile terminal such as a game machine or a mobile phone.

  Mechanical quantity sensor ... 100, fixed part ... 101, movable electrode ... 102, fixed electrode ... 103a, 103b, 103c, 103d, semiconductor substrate ... 104

Claims (1)

A fixed part;
A fixed electrode disposed apart from the fixed part;
One end portion is supported by the fixed portion, and includes a movable electrode that is displaceable with respect to the fixed portion and the fixed electrode,
The movable electrode is deformed by an applied external force and contacts a part of the fixed electrode;
A mechanical quantity sensor that detects the magnitude of the external force based on a change in electric resistance value between the fixed portion and the fixed electrode when the movable electrode contacts the fixed electrode.