JP2011242337A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which can suppress a degradation of detection accuracy of a dynamic quantity by a thermal stress and an external stress.SOLUTION: A semiconductor device includes a sensor chip and a substrate which are connected through a bump. The sensor chip includes a semiconductor substrate comprised by sequentially laminating a board, an insulation layer and a semiconductor layer. A sensing part formed on the semiconductor substrate includes: an anchor part which comprises the insulation layer and the semiconductor layer, and is fixed on the board; a floating part in which the insulation layer is removed, and which comprises the semiconductor layer and floats from the board. The anchor part includes a fixed anchor part and a movable anchor part. The floating part includes: a fixed electrode supported by the fixed anchor part; a movable part supported by movable anchor part; a movable electrode provided in the movable part; a connection part to which the bump is connected. The connection part includes a fixed connection part connected to the fixed electrode through the fixed anchor part and a movable connection part connected to the movable part through the movable anchor part.

Description

  The present invention relates to a semiconductor device including a sensor chip including a sensing unit that detects a mechanical quantity by a change in capacitance, and a base that is mechanically and electrically connected to the sensor chip via a bump. .

  Conventionally, for example, as disclosed in Patent Document 1, a capacitive semiconductor sensor device including a sensor chip formed with a dynamic quantity detection unit having a detection axis in one direction and a circuit chip having a signal processing circuit has been proposed. Has been. In the capacitive semiconductor sensor device disclosed in Patent Document 1, the sensor chip and the circuit chip are mechanically and electrically connected via bumps.

JP 2008-101980 A

  In the capacitive semiconductor sensor device disclosed in Patent Document 1, the sensor chip mainly includes a support substrate, an oxide film stacked on the support substrate, and a single crystal silicon layer stacked on the oxide film. It is constituted by. The above-described mechanical quantity detection unit is formed by processing this SOI substrate by a micromachine technique. In Patent Document 1, an acceleration detection unit including a fixed electrode unit and a movable electrode unit is employed as the mechanical quantity detection unit.

  The fixed electrode portion that constitutes the acceleration detection unit includes a base and a fixed electrode that extends from the base. As shown in FIG. 1B of Patent Document 1, the base portion is composed of a support substrate, an oxide film, and a single crystal silicon layer, and the fixed electrode is composed of a single crystal silicon layer. Electrode pads are formed on the upper surface of the base, and bumps are connected to the electrode pads. Further, the fixed electrode is supported by the support substrate in a cantilevered state by the base, and cannot be displaced with respect to the support substrate.

  The movable electrode part constituting the acceleration detection part is composed of an anchor part, a weight part connected to the anchor part, a beam part provided on the weight part, and a movable electrode extending from the weight part. As shown in FIG. 1C of Patent Document 1, the anchor portion is composed of a support substrate, an oxide film, and a single crystal silicon layer, and the weight portion is composed of a single crystal silicon layer. An electrode pad is formed on the upper surface of the anchor portion, and a bump is connected to the electrode pad. The weight part is supported by the support substrate in a cantilevered state by the anchor part, and can be displaced in the detection axis direction by the beam part.

  By the way, as described above, the sensor chip and the circuit chip are mechanically and electrically connected via the bumps. Each of the anchor portion and the base portion includes a support substrate, an oxide film, and a single crystal silicon layer, and electrode pads to which bumps are connected are formed on the upper surfaces of the anchor portion and the base portion, respectively. According to this, the sensor chip and the circuit chip are firmly connected via the bumps. Therefore, thermal stress caused by the difference in coefficient of linear expansion between the bump and the sensor chip and external stress applied to the capacitive semiconductor sensor device are applied to the weight part and the fixed electrode via the connection part between the bump and the sensor chip. It is easy to be applied. When the above-described stress is applied to the weight part or the fixed electrode, there is a possibility that the displacement of the weight part fluctuates, or that the movable electrode or the fixed electrode provided on the weight part is distorted. If such a problem occurs, the capacitance of the capacitor constituted by the movable electrode and the fixed electrode may fluctuate, and the acceleration detection accuracy may be reduced.

  In view of the above problems, an object of the present invention is to provide a semiconductor device in which the detection accuracy of a mechanical quantity is suppressed from being reduced by thermal stress or external stress.

  In order to achieve the above-described object, the invention according to claim 1 includes a sensor chip including a sensing unit that detects a mechanical quantity based on a change in capacitance of a capacitor constituted by a fixed electrode and a movable electrode, and a bump. A semiconductor device including a substrate mechanically and electrically connected to the sensor chip, the sensor chip having a semiconductor substrate on which a sensing unit is formed, the semiconductor substrate being connected to the substrate The insulating layer and the semiconductor layer are sequentially stacked, and the sensing unit includes the insulating layer and the semiconductor layer. The anchor portion is fixed to the substrate, and the insulating layer is removed to form the semiconductor layer. A floating part that floats against the fixed anchor part and a movable anchor part, and the floating part includes a fixed electrode supported by the fixed anchor part and a movable anchor part. Supported and solid A movable portion capable of being displaced in a direction in which the electrode and the movable electrode face each other; a movable electrode provided on the movable portion; and a connection portion to which the bump is connected. The connection portion is a fixed anchor portion. A fixed connection portion that is mechanically and electrically connected to the fixed electrode via a movable anchor portion, and a movable connection portion that is mechanically and electrically connected to the movable portion via a movable anchor portion. And

  Thus, according to the present invention, the connecting portion to which the bump is connected is mechanically connected to the electrode and the movable portion via the anchor portion. According to this, the thermal stress caused by the difference in linear expansion coefficient between the bump and the sensor chip (semiconductor layer) and the external stress applied to the semiconductor device are transferred to the electrode and the movable part via the connection part and the anchor part. Is transmitted to. The connection portion described above is made of a semiconductor layer and floats with respect to the substrate. Therefore, the connecting portion is easily bent by the stress described above, and the stress transmitted to the electrode and the movable portion is reduced by the bending of the connecting portion. Thereby, it is suppressed that the detection accuracy of a mechanical quantity falls by the above-mentioned stress.

  As described above, the connection portion is mechanically connected to the electrode and the movable portion via the anchor portion fixed to the substrate. Therefore, when a connection part bends by stress, it is suppressed that an electrode and a movable part bend with the bending of the connection part.

  A configuration in which the sensor chip and the base are mechanically connected not only via the bumps but also via ribs that define the distance between the sensor chip and the base is preferable.

  In the step of connecting the sensor chip and the substrate (hereinafter referred to as a connection step), pressure is applied to the bumps, and the connection portion may be bent by the pressure. On the other hand, in the present invention, the interval between the sensor chip and the substrate is defined by the rib. Therefore, in the connection step described above, the pressure acting on the connection portion becomes a predetermined value or less, and bending of the connection portion is suppressed.

  In the present invention, since the sensor chip and the substrate are mechanically connected by the rib, the mechanical connection strength between the sensor chip and the substrate is reinforced. Thereby, it is suppressed that damage, such as a crack, arises in a bump, and it is suppressed that the mechanical and electrical connection reliability of a sensor chip and a base | substrate is reduced.

  The rib according to claim 2 is preferably a rib made of an elastic material containing an additive having higher rigidity than that of the elastic material, as described in claim 3.

  The shape of the rib according to claim 3 is deformed by pressure in the same manner as a member made of an elastic material containing no additive. However, when the rib is deformed by pressure, the rigidity of the rib is increased by the additive contained in the elastic material, and the shape thereof is difficult to deform. Therefore, when pressure is applied to the ribs in the connecting step described above and the rigidity of the ribs is increased, the distance between the sensor chip and the base is suppressed from becoming narrower than the originally designed value, and the distance between the sensor chip and the base is reduced. Is maintained at a predetermined value. Thereby, in the above-described connecting step, the pressure acting on the connecting portion becomes a predetermined value or less, and bending of the connecting portion is suppressed.

  Further, since the rib is mainly formed of an elastic material, even if vibration is generated in the sensor chip or the base body due to external stress applied to the semiconductor device, the vibration can be reduced by the rib. As a result, it is possible to suppress the vibration caused by the external stress from being applied to the sensing unit, and to suppress the detection accuracy of the mechanical quantity from being reduced by the external stress.

  According to a fourth aspect of the present invention, there are a plurality of bumps, and each of the plurality of bumps, the sensor chip, and the substrate is mechanically connected through an insulating member, and the plurality of bumps and the insulating member surround the sensing unit. The rib is annular, the annular rib surrounds the periphery of the sensing unit, and the periphery of the bumps and the insulating member is surrounded. The sensing unit is provided in a vacuum atmosphere, and sensing It is preferable that the portion is double-blocked by the sensor chip, the base, the plurality of bumps, the insulating member, and the rib.

  For example, when an inertial force due to an acceleration motion is applied to the semiconductor device, the movable part varies due to the inertial force, and the facing distance between the fixed electrode and the movable electrode varies with the variation. In the case where the sensing unit is arranged in an air atmosphere, air damping occurs between the fixed electrode and the movable electrode due to the above-described fluctuation of the movable unit, which may reduce the detection accuracy of the mechanical quantity. . Therefore, conventionally, a configuration is adopted in which the above-described air damping is suppressed by arranging the sensing unit in a vacuum atmosphere. However, in this case, there arises a problem of airtightness of a member that seals the sensing unit. On the other hand, in the present invention, the sensing unit provided in the vacuum atmosphere is double-blocked by the sensor chip, the base, the plurality of bumps, the insulating member, and the rib. Thereby, airtightness is ensured.

  As described in claims 5 and 6, the sensing unit can employ a configuration for detecting acceleration or angular velocity as a mechanical quantity.

  In addition, as described in claim 7, a circuit chip including a processing circuit for processing an output signal of the sensor chip can be adopted as the base.

It is sectional drawing which shows schematic structure of the acceleration sensor which concerns on 1st Embodiment. It is sectional drawing which shows schematic structure of the acceleration sensor which concerns on 1st Embodiment. It is a top view which shows the opposing surface with the circuit chip in a sensor chip. It is a top view which shows the opposing surface with the sensor chip in a circuit chip. It is sectional drawing which shows the sensor chip before connecting with a circuit chip. It is sectional drawing which shows the circuit chip before connecting with a sensor chip.

Hereinafter, an embodiment in which a semiconductor device according to the present invention is applied to an acceleration sensor for detecting acceleration will be described with reference to the drawings.
(First embodiment)
1 and 2 are cross-sectional views showing a schematic configuration of the acceleration sensor according to the first embodiment. FIG. 3 is a plan view showing a surface of the sensor chip facing the circuit chip. FIG. 4 is a plan view showing a surface of the circuit chip that faces the sensor chip. FIG. 5 is a cross-sectional view showing the sensor chip before being connected to the circuit chip. FIG. 6 is a cross-sectional view showing the circuit chip before being connected to the sensor chip. The cross-sectional view shown in FIG. 1 corresponds to the cross-sectional view taken along the line AA shown in FIGS. 3 and 4, and the cross-sectional view shown in FIG. 2 is the cross-sectional view taken along the line BB shown in FIGS. It corresponds to.

  In the following, the direction in which the fixed electrode 20 and the movable electrode 22 described later face each other is referred to as a detection axis direction, the direction in which the sensor chip and the circuit chip face each other is referred to as a thickness direction, and the detection axis direction and the thickness. A direction perpendicular to the vertical direction is indicated as a crossing direction.

  As shown in FIGS. 1 and 2, the acceleration sensor 100 includes a sensor chip 10 and a circuit chip 50 as main parts. The acceleration sensor 100 has a stack structure in which the sensor chip 10 is stacked on the circuit chip 50, and the sensor chip 10 and the circuit chip 50 are mechanically and electrically connected to each other through the bumps 70. In the present embodiment, the sensor chip 10 and the circuit chip 50 are mechanically connected not only via the bumps 70 but also via the ribs 71.

  As will be described later, the bump 70 is connected to the connection portion 23 of the sensor chip 10, and this connection configuration is a main feature of the present invention. This feature point and its effect will be described later.

  The sensor chip 10 includes a SOI substrate 14 in which a substrate 11 made of single crystal silicon, an insulating layer 12 made of an oxide film, and a semiconductor layer 13 made of single crystal silicon are sequentially laminated, and the SOI substrate 14 is made known micro-machine technology. And a sensing unit 15 formed by processing into a predetermined shape.

  The sensing unit 15 includes an insulating layer 12 and a semiconductor layer 13, an anchor portion 16 fixed to the substrate 11, and the floating layer that floats with respect to the substrate 11 that includes the semiconductor layer 13 after the insulating layer 12 is removed. Part 17.

  The anchor portion 16 has a fixed anchor portion 18 and a movable anchor portion 19. As shown in FIG. 3, two anchor portions 18 and 19 are formed on the SOI substrate 14. Specifically, the two fixed anchor portions 18 face each other in the crossing direction via a movable portion 21 described later, and the two movable anchor portions 19 face each other in the detection axis direction via the movable portion 21. Each of the anchor portions 18 and 19 is formed on the SOI substrate 14. In FIG. 3, in order to clarify the formation position of the anchor portion 16, a portion constituting a part of the anchor portion 16 in the insulating layer 12 is indicated by a broken line. The fixed anchor portion 18 has a U shape, and the movable anchor portion 19 has a rectangular shape.

  The floating portion 17 includes a fixed electrode 20 supported by the fixed anchor portion 18, a movable portion 21 supported by the movable anchor portion 19 and capable of being displaced in the detection axis direction, and a movable electrode 22 provided on the movable portion 21. And a connection portion 23 to which the bump 70 is connected. The movable portion 21 described above includes a rectangular weight portion 24 whose longitudinal direction extends along the detection axis direction, and an annular beam portion 25 that allows the weight portion 24 to be displaced in the detection axis direction. In addition, the connection portion 23 described above mechanically connects the fixed connection portion 26 for mechanically and electrically connecting the fixed electrode 20 and the circuit chip 50, the movable portion 21 (movable electrode 22), and the circuit chip 50. And a movable connection portion 27 for electrical connection.

  As shown in FIG. 3, the fixed electrode 20 has a rectangular shape whose longitudinal direction is along the intersecting direction, one end of which is supported by the fixed anchor portion 18, and the other end is open. Similarly, the movable electrode 22 also has a rectangular shape whose longitudinal direction extends in the intersecting direction, one end of which is connected to the weight portion 24 and the other end is open. The plurality of fixed electrodes 20 extend from the fixed anchor portion 18 in a comb-teeth shape, and the plurality of movable electrodes 22 extend from the weight portion 24 in a comb-teeth shape. The plurality of movable electrodes 22 having a shape engage with each other, so that the fixed electrode 20 and the movable electrode 22 face each other in the detection axis direction. These two electrodes 20 and 22 constitute a plurality of capacitors, and acceleration is detected based on the fluctuation of the capacitance of the capacitors.

  As shown in FIG. 3, both ends of the weight portion 24 are supported by the movable anchor portion 19. A beam portion 25 is formed at each end of the weight portion 24, and a movable electrode 22 is formed at a central portion of the weight portion 24 located between the two beam portions 25. With this configuration, when acceleration is applied in the detection axis direction, the beam portion 25 is bent by the inertial force, and the weight portion 24 is changed in the detection axis direction according to the bending, and the fixed electrode is accompanied by the change. The distance between the electrode 20 and the movable electrode 22 varies.

  As shown in FIG. 3, the fixed connection part 26 is mechanically and electrically connected to the fixed electrode 20 via the fixed anchor part 18, and the movable connection part 27 is connected to the movable part via the movable anchor part 19. 21 and mechanically and electrically connected. More specifically, the fixed connection portion 26 is mechanically and electrically connected to the fixed electrode 20 via the semiconductor layer 13 fixed to the substrate 11 via the insulating layer 12 in the fixed anchor portion 18 to be movable connected. The part 27 is mechanically and electrically connected to the movable connection part 27 via the semiconductor layer 13 fixed to the substrate 11 via the insulating layer 12 in the movable anchor part 19. As shown in FIGS. 1 to 3, pads 28 for connecting to the bumps 70 are formed on the upper surfaces (surfaces on the circuit chip 50 side) of the connection portions 26 and 27. Also, four pads 28 are formed in a portion of the sensor chip 10 where the shape is not processed (hereinafter, referred to as a frame portion 29).

  As described above, in the present embodiment, the sensor chip 10 and the circuit chip 50 are mechanically connected via the rib 71, but in FIG. A region to which is connected is indicated by a two-dot chain line. A region to which the rib 71 is connected is formed in the frame portion 29 described above, and the shape thereof is a U-shape. Most of the periphery of the sensing unit 15 is surrounded by these two U-shaped regions.

  The circuit chip 50 is obtained by forming a semiconductor substrate 51 and a processing circuit (not shown) for processing the output signal of the sensor chip 10 on the semiconductor substrate 51. As shown in FIG. 4, a plurality of pads 52 corresponding to the positions where the pads 28 of the sensor chip 10 are formed are formed on the surface 51 a of the semiconductor substrate 51 facing the sensor chip 10. In the present embodiment, two U-shaped ribs 71 are formed on the facing surface 51 a in addition to the pad 52. The upper surface of the rib 71 (the surface on the sensor chip 10 side) is mechanically connected to a region of the sensor chip 10 where the rib 71 is connected. The processing circuit described above is formed in a portion of the semiconductor substrate 51 surrounded by a plurality of pads 52 or ribs 71.

  The bump 70 is for mechanically and electrically connecting the sensor chip 10 and the circuit chip 50. In the present embodiment, the sensor chip 10 and the circuit chip 50 are mechanically and electrically connected by eight bumps 70. Of these eight bumps 70, two bumps 70 are connected to the pad 28 of the fixed connection portion 26, and two bumps 70 are connected to the pad 28 of the movable connection portion 27. The remaining four bumps 70 are connected to the pads 28 of the frame portion 29. The bump 70 connected to the fixed connection portion 26 functions to output the capacitance change of the capacitor formed by the fixed electrode 20 and the movable electrode 22 to the circuit chip 50, and the bump 70 connected to the movable connection portion 27. 70 fulfills the function of supplying a constant voltage to the movable part 21 (movable electrode 22). The bumps 70 connected to the frame portion 29 serve to supply a constant voltage to the sensor chip 10 for keeping the potential of the entire sensor chip 10 constant. As shown in FIGS. 1 and 2, the bump 70 is covered and protected by an insulating member 72, and the sensor chip 10 and the circuit chip 50 are mechanically connected by the insulating member 72.

  The rib 71 functions to define the distance between the sensor chip 10 and the circuit chip 50. As shown in FIG. 4, two U-shaped ribs 71 are formed on the circuit chip 50, and the two ribs 71 surround the sensing unit 15 and the processing circuit. The rib 71 according to the present embodiment includes an elastic material containing an additive having higher rigidity than the elastic material. The rib 71 is deformed by pressure in the same manner as a member made of an elastic material containing no additive, but when the shape is deformed by pressure, the rigidity of the rib 71 is increased by the additive contained in the elastic material. However, the shape is difficult to deform. For example, silicone rubber having a Young's modulus of the order of 1 MPa or less can be used as the elastic material, and resin beads having a diameter of about several tens of μm can be used as the additive.

  Next, a method for manufacturing the acceleration sensor 100 according to this embodiment will be described. First, the SOI substrate 14 on which the pad 28 and the sensor side bump 73 are formed is prepared. Then, the sensing unit 15 is formed on the SOI substrate 14. Thereby, the sensor chip 10 shown in FIG. 5 is prepared.

  Next, a semiconductor substrate 51 on which a processing circuit and ribs 71 are formed is prepared. Then, pads 52 and circuit side bumps 74 are formed on the semiconductor substrate 51. Thereby, the circuit chip 50 shown in FIG. 6 is prepared. The rib 71 described above is longer than the facing distance between the sensor chip 10 and the circuit chip 50 at the time of completion, and is formed by using a known semiconductor photolithography technique.

  Finally, the sensor chip 10 and the circuit chip 50 are opposed to each other so that the sensor-side bump 73 and the circuit-side bump 74 are in contact with each other, and predetermined heat and pressure are applied, so that the sensor-side bump 73 The bumps 70 are formed by connecting the circuit side bumps 74. In this step, the rib 71 is compressed, the length along the thickness direction is shortened, and the rigidity is increased. In addition, the sensor chip 10 side surface of the rib 71 and the sensor chip 10 are thermocompression bonded, and the sensor chip 10 and the circuit chip 50 are mechanically connected via the rib 71. Through the above steps, the acceleration sensor 100 according to the present embodiment is manufactured.

  Next, functions and effects of the acceleration sensor 100 according to the present embodiment will be described. As described above, the connection portion 23 to which the bump 70 is connected is mechanically connected to the electrodes 20 and 22 and the movable portion 21 via the anchor portion 16. According to this, thermal stress caused by the difference in linear expansion coefficient between the bump 70 and the sensor chip 10 (semiconductor layer 13) and external stress applied to the acceleration sensor 100 are caused to pass through the connection portion 23 and the anchor portion 16. Thus, the signal is transmitted to the electrodes 20 and 22 and the movable portion 21. The connection portion 23 described above is made of the semiconductor layer 13 and floats with respect to the substrate 11. Therefore, the connecting portion 23 is easily bent by the stress described above, and the stress transmitted to the electrodes 20 and 22 and the movable portion 21 is reduced by the bending of the connecting portion 23. Thereby, it is suppressed that the detection accuracy of a mechanical quantity falls by the above-mentioned stress.

  As described above, the connection portion 23 is mechanically connected to the electrodes 20 and 22 and the movable portion 21 via the anchor portion 16 fixed to the substrate 11. Therefore, when the connection part 23 bends by stress, it is suppressed that the electrodes 20, 22 and the movable part 21 bend with the bending of the connection part 23.

  In the present embodiment, the sensor chip 10 and the circuit chip 50 are mechanically connected not only via the bumps 70 but also via the ribs 71. The rib 71 includes an elastic material containing an additive having higher rigidity than the elastic material. Therefore, when the shape of the rib 71 is deformed by pressure, the rigidity of the rib 71 is increased by the additive contained in the rib 71, and the shape of the rib 71 is difficult to be deformed. According to this, when pressure is applied to the rib 71 in the step of connecting the sensor chip 10 and the circuit chip 50 via the bump 70 and the rigidity of the rib 71 increases, the distance between the sensor chip 10 and the circuit chip 50 is increased. Is suppressed from being initially designed, and the distance between the sensor chip 10 and the circuit chip 50 is kept at a predetermined value. Thereby, in the connection process between the sensor chip 10 and the circuit chip 50, the pressure acting on the connection portion 23 becomes a predetermined value or less, and the bending of the connection portion 23 is suppressed.

  In this embodiment, since the sensor chip 10 and the circuit chip 50 are mechanically connected via the rib 71, the mechanical connection strength between the sensor chip 10 and the circuit chip 50 is reinforced. Thereby, the occurrence of damage such as cracks in the bumps 70 is suppressed, and the mechanical and electrical connection reliability between the sensor chip 10 and the circuit chip 50 is suppressed from decreasing.

  Furthermore, since the rib 71 is mainly formed of an elastic material, even if vibration occurs in the sensor chip 10 or the circuit chip 50 due to external stress applied to the acceleration sensor 100, the rib 71 causes the vibration. Can be relaxed. As a result, the vibration caused by the external stress is suppressed from being applied to the sensing unit 15, and the acceleration detection accuracy is suppressed from being reduced by the external stress.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In this embodiment, the example which applied the semiconductor device which concerns on this invention to the acceleration sensor which detects an acceleration was shown. However, the semiconductor device according to the present invention is not limited to the above example, and can be applied to, for example, an angular velocity sensor.

  In the present embodiment, an example in which the rib 71 has a U-shape has been shown. However, the shape of the rib 71 is not limited to the above example. For example, it may be annular or rectangular.

  In the present embodiment, an example in which the sensor chip 10 and the circuit chip 50 are mechanically connected by the two ribs 71 is shown. However, the number of ribs 71 is not limited to the above example, and may be one or three or more.

  In addition, when the sensor chip 10 and the circuit chip 50 are mechanically connected by one rib 71, the rib 71 preferably has an annular shape. By the annular rib 71, the sensing unit 15 that detects the mechanical quantity, the processing circuit that processes the output signal of the sensing unit 15, and the bump 70 that mechanically and electrically connects the sensor chip 10 and the circuit chip 50 are provided. It can be set as the structure where the circumference was enclosed. With this configuration, the sensing unit 15, the processing circuit, and the bump 70 are accommodated in an internal space constituted by the rib 71, the sensor chip 10 (SOI substrate 14), and the circuit chip 50 (semiconductor substrate 51). Can protect from dust, etc.

  When the above configuration is employed, it is preferable to employ a configuration in which the periphery of the sensing unit 15 and the processing circuit is surrounded by a plurality of bumps 70 and an insulating member 72 that covers and protects the bumps 70. According to this, the sensing unit 15 and the processing circuit can be doubly closed by the sensor chip 10, the circuit chip 50, the plurality of bumps 70, the insulating member 72, and the annular rib 71.

  Furthermore, in the case of the double closed configuration described above, the sensing unit 15 may be provided in a vacuum atmosphere in order to suppress the occurrence of air damping between the fixed electrode 20 and the movable electrode 22. According to this, the airtightness of the sensing unit 15 and the processing circuit is ensured, for example, as compared with the configuration in which the sensing unit 15 and the processing circuit are single-blocked by the bump 70 and the insulating member 72.

  When the sensor chip 10 and the circuit chip 50 are mechanically connected by the plurality of ribs 71, a predetermined distance may be provided between the plurality of ribs 71. According to this, a part of the rib 71 that is thermally expanded by the application of heat enters the gap between the adjacent ribs 71, so that the stress caused by the thermal expansion is suppressed from being applied to the sensor chip 10. In the case where the sensor chip 10 and the circuit chip 50 are mechanically connected by one rib 71, a plurality of notches may be formed in the rib 71 in order to achieve the above-described effect. It ’s fine.

  In this embodiment, the SOI substrate 14 on which the pad 28 and the sensor side bump 73 are formed is prepared, and the sensing unit 15 is formed on the SOI substrate 14. However, on the contrary, the SOI substrate 14 on which the sensing unit 15 is formed may be prepared, and the pad 28 and the sensor-side bump 73 may be formed on the SOI substrate 14. In order to realize this, the floating portion 17 of the sensing portion 15 may be fixed with a resist having low wettability, for example, when the pad 28 and the sensor side bump 73 are formed. As other methods, eutectic and plating methods can be employed.

  In this embodiment, the example which uses the circuit chip 50 in which the rib 71 was formed in the manufacturing process was shown. However, you may use the sensor chip 10 in which the rib 71 was formed. Alternatively, the sensor chip 10 in which the rib 71 is formed and the circuit chip 50 in which the rib 71 is formed may be used.

  In this embodiment, the example which forms the rib 71 by using a semiconductor photolithography technique was shown. However, the rib 71 may be formed using a dispenser.

DESCRIPTION OF SYMBOLS 10 ... Sensor chip 16 ... Anchor part 17 ... Moving part 23 ... Connection part 50 ... Circuit chip 70 ... Bump 71 ... Rib 100 ... Acceleration sensor

Claims (7)

A sensor chip including a sensing unit that detects a mechanical quantity by a capacitance change of a capacitor constituted by a fixed electrode and a movable electrode;
A semiconductor device comprising a substrate mechanically and electrically connected to a sensor chip via a bump,
The sensor chip has a semiconductor substrate on which the sensing unit is formed,
The semiconductor substrate is formed by sequentially laminating a substrate, an insulating layer, and a semiconductor layer,
The sensing unit is composed of the insulating layer and the semiconductor layer, an anchor portion fixed to the substrate, and the floating portion floating with respect to the substrate, the insulating layer being removed and the semiconductor layer, Have
The anchor portion has a fixed anchor portion and a movable anchor portion,
The floating portion includes the fixed electrode supported by the fixed anchor portion, the movable portion supported by the movable anchor portion, and movable in a direction in which the fixed electrode and the movable electrode face each other, and the movable portion The movable electrode provided in the part, and a connection part to which the bump is connected,
The connection portion is mechanically and electrically connected to the movable portion via the fixed anchor portion and the fixed connection portion mechanically and electrically connected to the fixed electrode via the fixed anchor portion. And a movable connection portion.   2. The semiconductor according to claim 1, wherein the sensor chip and the base are mechanically connected not only via the bumps but also via ribs that define a distance between the sensor chip and the base. apparatus.   The semiconductor device according to claim 2, wherein the rib includes an elastic material containing an additive having higher rigidity than the elastic material. The bump is plural,
Each of the plurality of bumps, the sensor chip, and the base body is mechanically connected via an insulating member, and the periphery of the sensing unit is surrounded by the plurality of bumps and the insulating member.
The rib is annular;
Surrounding the periphery of the sensing unit, the plurality of bumps and the insulating member are surrounded by the annular rib.
The sensing unit is provided in a vacuum atmosphere,
The said sensing part is obstruct | occluded doubly by the said sensor chip, the said base | substrate, the said several bump, the said insulating member, and the said rib, The Claim 2 or Claim 3 characterized by the above-mentioned. The semiconductor device described.   The semiconductor device according to claim 1, wherein the sensing unit detects acceleration as the mechanical quantity.   The semiconductor device according to claim 1, wherein the sensing unit detects an angular velocity as the mechanical quantity.   The semiconductor device according to claim 1, wherein the base is a circuit chip including a processing circuit that processes an output signal of the sensor chip.

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