JP2015010871A - Physical quantity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a physical quantity sensor capable of reducing a contact resistance between a laminated substrate and a contact part without increasing manufacturing steps.SOLUTION: A laminated substrate is constituted of a P-type silicon substrate having a resistivity of 0.01-0.2 [Ω-cm]. Hereby, a contact resistance can be reduced without forming a high concentration layer on the laminated substrate.

Description

  In the present invention, a hermetic chamber is formed between the first substrate and the second substrate, and a sensing unit that outputs a sensor signal corresponding to a physical quantity is provided in the hermetic chamber and the second substrate is maintained at a predetermined potential. The present invention relates to a physical quantity sensor.

  Conventionally, for example, in Patent Document 1, a first substrate on which a sensing unit that outputs a sensor signal corresponding to a physical quantity is formed, and a second substrate that is bonded to the first substrate so as to seal the sensing unit, There has been proposed a physical quantity sensor comprising: Note that the first substrate has a silicon substrate on which a sensing portion is formed, and the second substrate has a structure in which a silicon substrate to be a bonded substrate is covered with an insulating film.

  In such a physical quantity sensor, since the first and second substrates are bonded so as to seal the sensing unit, it is possible to prevent foreign substances and the like from adhering to the sensing unit.

JP 2010-171368 A

  However, in the physical quantity sensor, a parasitic capacitance is generated between the first substrate and the second substrate, but the potential of the second substrate is not stable because the potential of the second substrate (bonded substrate) is in a floating state. It becomes stable. For this reason, the parasitic capacitance generated between the first substrate and the second substrate varies, and the change in the parasitic capacitance becomes noise, so that the detection accuracy is lowered.

  In order to solve this problem, a contact portion made of aluminum or the like is formed on a bonded substrate that constitutes the second substrate, and the bonded substrate and an external circuit are connected via the contact portion. It is conceivable to maintain a constant potential. That is, it is conceivable to make the parasitic capacitance generated between the first substrate and the second substrate constant. In this case, if the contact resistance between the bonded substrate and the contact portion is high, it is difficult to apply a sufficient charge to the bonded substrate, so it is desirable to reduce the contact resistance.

  Therefore, simply, it is conceivable to reduce the contact resistance by forming a high concentration layer on the bonded substrate and connecting the contact portion to the high concentration layer.

  However, in the structure in which the high concentration layer is formed on the bonded substrate in this way, there is a problem that a process for forming the high concentration layer is required and the manufacturing process is increased.

  An object of this invention is to provide the physical quantity sensor which can reduce the contact resistance of a bonded substrate and a contact part, without increasing a manufacturing process in view of the said point.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a first substrate (10) having one surface (10a) and a surface (40a), wherein the one surface faces one surface of the first substrate. And a second substrate (40) bonded to the first substrate, and a hermetic chamber (90) is formed between the first and second substrates, and a sensor signal corresponding to a physical quantity is output to the hermetic chamber. The physical quantity sensor in which the part (60) is arranged is characterized by the following points.

  That is, the second substrate is composed of a P-type silicon substrate having a resistivity of 0.01 to 0.2 [Ω · cm], and is connected to a contact portion (80) configured using a metal material. Thus, it has a bonded substrate (41) maintained at a predetermined potential (see FIG. 4).

  According to this, it is possible to reduce the contact resistance without increasing the manufacturing process.

  For example, as in the invention described in claim 2, the first substrate is an SOI (Silicon on Insulator) substrate in which a support substrate (11), an insulating film (12), and a semiconductor layer (13) are sequentially stacked. The surface of the semiconductor layer opposite to the insulating film can be a surface of the first substrate.

  In this case, as in the invention described in claim 3, at least a part of the sensing unit is formed in the semiconductor layer, and a periodic voltage carrier wave is input to the part, The substrate can be made of a silicon substrate having a floating potential and a resistivity of 0.01 to 20 [Ω · cm] (see FIG. 6).

  According to this, even when a carrier wave is input to the semiconductor layer, the potential of the support substrate can be prevented from varying from part to part, and the detection accuracy can be prevented from decreasing.

  Further, as in the invention described in claim 4, the support substrate is composed of a P-type silicon substrate having a resistivity of 0.01 to 0.2 [Ω · cm], and is composed of a metal material. Further, it can be maintained at a predetermined potential by being connected to an external circuit through the contact portion.

  According to this, since the electric potential of a support substrate is maintained, it can suppress that detection accuracy falls.

  And like invention of Claim 5, a semiconductor layer can be comprised with the P-type silicon substrate whose resistivity is 0.01-0.03 [ohm * cm] (FIG. 7). reference). Further, as in the invention described in claim 6, the semiconductor layer can be formed of an N-type silicon substrate having a resistivity of 0.01 to 0.2 [Ω · cm].

According to this, the sheet resistance (depletion layer resistance) is 1.0 Ω · cm ² or less, and it is possible to suppress a decrease in detection accuracy.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is sectional drawing of the acceleration sensor in 1st Embodiment of this invention. It is a top view by the side of the 2nd board | substrate in the 1st board | substrate shown in FIG. It is a top view by the side of the 1st substrate in the 2nd substrate shown in FIG. It is a figure which shows the relationship between the resistivity of a P-type silicon substrate, and contact resistance. It is a figure which shows the circuit structure of a sensing part and a CV conversion circuit. It is a figure which shows the relationship between the resistivity of a support substrate, and the phase difference of the electric potential of the part which opposes an anchor part among the support boards, and the electric potential of the part which opposes the part most distant from the torsion beam in a 2nd site | part. . It is a figure which shows the relationship between the resistivity of a semiconductor layer, and depletion layer resistance. It is sectional drawing which shows the manufacturing process with respect to a 1st board | substrate. It is sectional drawing which shows the manufacturing process with respect to a bonded substrate board. It is sectional drawing which shows the manufacturing process of the acceleration sensor shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example in which the physical quantity sensor of the present invention is applied to an acceleration sensor that detects acceleration will be described.

  As shown in FIG. 1, the acceleration sensor is configured by stacking a first substrate 10 and a second substrate 40. 1 corresponds to a cross section taken along the line II in FIG. 2 and FIG.

In the present embodiment, the first substrate 10 is an SOI (Silicon on Insulator) substrate in which a semiconductor layer 13 is disposed on a support substrate 11 via an insulating film 12, and one surface 10 a is insulated from the semiconductor layer 13. It is comprised by the surface on the opposite side to the film | membrane 12 side. The support substrate 11 and the semiconductor layer 13 are composed of a silicon substrate, and the insulating film 12 is composed of SiO ₂ , SiN, or the like.

  As shown in FIGS. 1 and 2, the semiconductor layer 13 is micromachined to form a groove portion 14, and the movable portion 20 and the peripheral portion 30 are partitioned by the groove portion 14.

  Further, in order to prevent the movable portion 20 (frame portion 22, which will be described later) from coming into contact with the support substrate 11 and the insulating film 12, the support substrate 11 and the insulating film 12 are recessed in a portion facing the movable portion 20. 15 is formed.

  The movable portion 20 includes a rectangular frame-shaped frame portion 22 in which a planar rectangular opening portion 21 is formed, and a torsion beam 23 provided so as to connect opposite sides of the opening portion 21. The movable portion 20 is supported by the support substrate 11 by connecting the torsion beam 23 to the anchor portion 24 supported by the insulating film 12.

  Here, each direction of the x axis, the y axis, and the z axis in FIGS. 1 to 3 will be described. 1 to 3, the x-axis direction is the left-right direction in FIG. 1, the y-axis direction is the direction orthogonal to the x-axis in the plane of the first substrate 10, and the z-axis direction is the surface of the first substrate 10. The direction is normal to the direction.

  The torsion beam 23 is a member that becomes a rotation axis that becomes the rotation center of the movable portion 20 when an acceleration in the z-axis direction is applied, and is provided so as to divide the opening 21 into two in this embodiment.

  The frame portion 22 has an asymmetric shape with respect to the torsion beam 23 so that it can rotate around the torsion beam 23 when an acceleration in the z-axis direction is applied. In the present embodiment, the length of the frame portion 22 in the x-axis direction to the end of the portion farthest from the torsion beam 23 in the first portion 22a is farthest from the torsion beam 23 in the second portion 22b. The length to the end of the part is shorter than the length in the x-axis direction. That is, in the frame portion 22 of the present embodiment, the mass of the first part 22a is smaller than the mass of the second part 22b.

  In addition, pad portions 25 and 31 and a frame-shaped sealing portion 32 are formed on one surface 10 a (the surface of the semiconductor layer 13) of the first substrate 10. Specifically, the pad portion 25 is formed on the anchor portion 24 and connected to the anchor portion 24 (movable portion 20), and the pad portion 31 is formed on the peripheral portion 30 and connected to the peripheral portion 30 for sealing. The part 32 is formed in the peripheral part 30 so as to surround the movable part 20 (groove part 14).

  In addition, the pad part 31 is arrange | positioned in the area | region enclosed by the sealing part 32 among the peripheral parts 30, and the pad parts 25 and 31 and the sealing part 32 are comprised by aluminum etc. in this embodiment. Yes.

  Further, a frame-like spacer 33 surrounding the sealing portion 32 is formed on the outer edge portion of the peripheral portion 30 on the one surface 10 a of the first substrate 10. The spacer 33 maintains the distance between the first substrate 10 and the second substrate 40, and is composed of an insulating film such as an oxide film. Although not particularly limited, phosphorus or the like serving as an ion trap may be added to the oxide film constituting the spacer 33 in order to capture sodium ions or the like applied from the external environment.

  As shown in FIGS. 1 and 3, the second substrate 40 is bonded to the bonded substrate 41, the insulating film 42 formed on one side and the side of the bonded substrate 41 facing the first substrate 10, and the bonded substrate 41. The substrate 41 has an insulating film 43 formed on the other surface opposite to the first substrate 10 side. Then, one surface 40 a of the second substrate 40 is formed on the surface of the insulating film 42 facing the first substrate 10.

The bonded substrate 41 is made of a silicon substrate, the insulating film 42 is made of SiO ₂ , SiN or the like, and the insulating film 43 is made of TEOS or the like.

  The first and second wiring portions 51 and 52 are formed on the one surface 40 a of the second substrate 40. Specifically, the first wiring part 51 is formed in a portion facing the first part 22a, and includes a first fixed electrode 51a and a first fixed electrode that form a predetermined capacity with the first part 22a. And a first lead wiring 51b led out from 51a. Further, the second wiring portion 52 is formed in a portion facing the second portion 22b, and is pulled out from the second fixed electrode 52a and the second fixed electrode 52a that constitutes a predetermined capacity between the second portion 22b. Second lead wiring 52b. Thereby, the sensing part 60 which outputs the sensor signal according to acceleration by the movable part 20 and the 1st, 2nd fixed electrodes 51a and 52a is comprised.

  The first and second fixed electrodes 51a and 52a have the same planar shape, and form an equal capacity between the first and second portions 22a and 22b in a state where no acceleration is applied. The first and second lead wires 51b and 52b have circular shapes at the ends opposite to the first and second fixed electrodes 51a and 52a, respectively. And the part which opposes the 1st, 2nd fixed electrodes 51a and 52a among the frame parts 22 becomes a movable electrode.

  Further, on one surface 40 a of the second substrate 40, pad portions 53 and 54 are formed at portions facing the pad portion 25 and pad portion 31, and the sealing portion 32 is disposed at a portion facing the sealing portion 32. The sealing part 55 having the same shape as that is formed. The pad parts 53 and 54 and the sealing part 55 are made of aluminum or the like.

  Further, four through-electrode portions 70 that penetrate the second substrate 40 in the thickness direction (the stacking direction of the first and second substrates 10 and 40) are formed in the second substrate 40. In each through electrode portion 70, a through electrode 70 c is formed in a through hole 70 a that penetrates the insulating film 43, the bonded substrate 41, and the insulating film 42 via an insulating film 70 b, and the through electrode 70 c and the external circuit are formed on the insulating film 43. The pad portion 70d that is electrically connected to the pad is formed.

  The through electrode portions 70 are electrically connected to the first and second wiring portions 51 and 52 and the pad portions 53 and 54, respectively. That is, the through hole 70a in each through electrode part 70 is formed to reach the first and second wiring parts 51 and 52 and the pad parts 53 and 54, respectively. The two wiring portions 51 and 52 and the pad portions 53 and 54 are disposed in the through hole 70a so as to be electrically connected.

  Thereby, the movable portion 20 is connected to the through electrode 70c via the pad portions 25 and 53, and the first and second fixed electrodes 51a and 52a are connected to the through electrode 70c. In addition, the peripheral portion 30 is connected to the through electrode 70 c via the pad portions 31 and 54.

  Note that the through hole 70a of the through electrode portion 70 that is electrically connected to the first and second wiring portions 51 and 52 corresponds to the first and second lead wirings 51b and 52b in the first and second wiring portions 51 and 52, respectively. Of these, the first and second fixed electrodes 51a and 52a are formed so as to reach the end opposite to the side. In the present embodiment, the through hole 70a is cylindrical, the insulating film 70b is made of an insulating material such as TEOS, and the through electrode 70c is made of aluminum or the like.

  Further, a contact hole 43 a that opens a predetermined portion of the bonded substrate 41 is formed in the insulating film 43. In the contact hole 43a, a contact portion 80 for connecting the bonded substrate 41 and an external circuit and maintaining the bonded substrate 41 at a predetermined potential is embedded. The contact portion 80 is made of aluminum, like the through electrode 70c and the pad portion 70d.

  The above is the configuration of the second substrate 40 in the present embodiment. And the said 1st, 2nd board | substrates 10 and 40 are joined and integrated, and the acceleration sensor is comprised. Specifically, the first and second substrates 10 and 40 are integrated by metal bonding of the pad portion 25 and the pad portion 53, the pad portion 31 and the pad portion 54, and the sealing portion 32 and the sealing portion 55. It has become. The space between the first and second substrates 10 and 40 forms an airtight chamber 90, and the frame portion 22 and the first and second fixed electrodes 51 a and 52 a (sensing unit 60) are sealed in the airtight chamber 90. ing.

  Note that the distance between the first substrate 10 and the second substrate 40 is defined by the spacer 33. The hermetic chamber 90 is, for example, a vacuum.

  The above is the basic configuration of the acceleration sensor in the present embodiment. Next, the configuration of the support substrate 11, the semiconductor layer 13, and the bonded substrate 41 that are characteristic points of the present embodiment will be specifically described.

  As shown in FIG. 4, the contact resistance between silicon and aluminum is almost zero when the silicon resistivity is 0.2 Ω · cm or less. When the resistivity of silicon is greater than 0.2 Ω · cm, the contact resistance gradually increases as the resistivity of silicon increases. That is, silicon and aluminum are in ohmic contact when the resistivity of silicon is 0.2 Ω · cm or less, and are in Schottky contact when the resistivity of silicon is greater than 0.2 Ω · cm.

  FIG. 4 is a diagram showing the relationship between the contact resistance between P-type silicon and aluminum, but the relationship between the resistivity of silicon and the contact resistance even when a metal material such as gold other than aluminum is used. The same.

  For this reason, in this embodiment, the bonded substrate 41 is P-type, and is formed of a silicon substrate having a resistivity of 0.01 to 0.2 Ω · cm. In other words, the bonded substrate 41 is formed of a silicon substrate having a resistivity at which the contact resistance with the contact portion 80 is substantially zero.

  The lower limit of resistivity, 0.01 Ω · cm, is the lowest limit resistivity when actually forming a silicon substrate, and the same applies to the support substrate 11 and the semiconductor layer 13 described below. In addition, when the bonded substrate 41 is made of an N-type silicon substrate, if the contact resistance is made to be almost zero due to the work function with aluminum, the minimum limit resistivity when forming Si is obtained. A value lower than a certain 0.01 Ω · cm is required. For this reason, when the bonded substrate 41 is composed of an N-type silicon substrate, it is necessary to form a high-concentration layer in a portion in contact with the contact portion 80, which increases the manufacturing process.

  Further, as shown in FIG. 5, the acceleration sensor as described above is a fully differential type composed of an operational amplifier 101, first and second capacitors 102a and 102b, and first and second switches 103a and 103b. It may be used by being connected to the CV conversion circuit 110.

  Specifically, the first capacitor 102a and the first switch 103a are arranged in parallel between the inverting input terminal of the operational amplifier 101 and the + side output terminal. The second capacitor 102b and the second switch 103b are disposed in parallel between the non-inverting input terminal of the operational amplifier 101 and the negative output terminal.

  The operational amplifier 101 has an inverting input terminal electrically connected to the first fixed electrode 51a and a non-inverting input terminal electrically connected to the second fixed electrode 52a. In addition, a pulse-shaped periodic carrier wave having an amplitude between a voltage Vcc and 0 V and having a predetermined frequency is input to the movable unit 20.

  In this state, when acceleration in the z-axis direction is applied, the frame portion 22 rotates according to the acceleration with the torsion beam 23 as the rotation axis. And since the capacity | capacitance between the 1st site | part 22a and the 1st fixed electrode 51a and the capacity | capacitance between the 2nd site | part 22b and the 2nd fixed electrode 52a change according to an acceleration, the CV conversion circuit 110 Sensor signal Vout (V1-V2) corresponding to the capacity is output.

  In this case, since the potential of the support substrate 11 is in a floating state, the potential of the support substrate 11 is displaced depending on the carrier wave input to the anchor portion 24 (frame portion 22). At this time, since the support substrate 11 has a resistivity, if the resistivity is large, the potential of the portion of the support substrate 11 that faces the anchor portion 24 via the insulating film 12 and the outer edge portion of the frame portion 22 And a potential of the portion facing each other. That is, the electrostatic force (parasitic capacitance) generated between a portion of the support substrate 11 that faces the anchor portion 24 via the insulating film 12 and the anchor portion 24, and the outer edge of the frame portion 22 of the support substrate 11. The electrostatic force (parasitic capacitance) generated between the part facing the part and the outer edge part is different. For this reason, at the time of detection, the difference in electrostatic force becomes an output error, and the detection accuracy decreases.

  Therefore, as shown in FIG. 6, the support substrate 11 is composed of a silicon substrate having a resistivity of 0.01 to 20 Ω · cm.

  FIG. 6 shows a simulation result using a silicon substrate having a thickness of 120 μm, a width of 400 μm, and a length of 2 mm. Further, since the phase difference is the same between the P-type silicon substrate and the N-type silicon substrate, the support substrate 11 may be configured by either the P-type silicon substrate or the N-type silicon substrate.

Further, the semiconductor layer 13 (frame portion 22) detects charges generated due to a change in capacitance when acceleration is applied. However, in order to reduce the phase shift at the electrode interface to a negligible level, surface resistance (depletion) The layer resistance is preferably 1.0 Ω · cm ² or less. Therefore, as shown in FIG. 7, the semiconductor layer 13 is a P-type silicon substrate having a thickness of 0.01 to 0.03 Ω · cm or an N-type silicon substrate having a thickness of 0.01 to 0.2 Ω · cm. It is composed of a silicon substrate.

  Next, a method for manufacturing the acceleration sensor will be described with reference to FIGS.

  First, as shown in FIG. 8A, a support substrate 11 is prepared, and an insulating film 12 is formed on the support substrate 11 by a CVD (Chemical Vapor Deposition) method, thermal oxidation, or the like. As described above, the support substrate 11 is composed of an N-type silicon substrate or a P-type silicon substrate having a resistivity of 0.01 to 20 Ω · cm.

  Next, as shown in FIG. 8B, a mask (not shown) such as a resist or an oxide film is formed on the insulating film 12 and wet etching or the like is performed to form a recess 15 in the support substrate 11. To do.

  Subsequently, as illustrated in FIG. 8C, the first substrate 10 is formed by bonding the insulating film 12 and the semiconductor layer 13. The bonding between the insulating film 12 and the semiconductor layer 13 is not particularly limited, but can be performed as follows, for example.

First, the bonding surface of the insulating film 12 and the bonding surface of the semiconductor layer 13 are irradiated with N ₂ plasma, O ₂ plasma, or an Ar ion beam to activate the bonding surfaces of the insulating film 12 and the semiconductor layer 13. Then, alignment by an infrared microscope or the like is performed using an appropriately formed alignment mark, and the insulating film 12 and the semiconductor layer 13 are bonded by so-called direct bonding at room temperature to 550 ° C.

  As described above, the semiconductor layer 13 is a P-type silicon substrate having a resistivity of 0.01 to 0.03 Ω · cm, or an N-type having a resistivity of 0.01 to 0.2 Ω · cm. It is composed of a silicon substrate.

  Although the direct bonding is described as an example here, the insulating film 12 and the semiconductor layer 13 may be bonded by a bonding technique such as anodic bonding, intermediate layer bonding, or fusion bonding. And after joining, you may perform the process which improves joining quality, such as high temperature annealing. Further, after bonding, the semiconductor layer 13 may be processed to a desired thickness by grinding and polishing.

  Next, as shown in FIG. 8D, an insulating film is formed on one surface 10a of the first substrate 10 by a CVD method or the like. Then, the spacer 33 is formed by patterning the insulating film by reactive ion etching or the like using a mask (not shown) such as a resist or an oxide film.

  Thereafter, as shown in FIG. 8E, a metal film is formed on one surface 10a of the first substrate 10 by a CVD method or the like. And the pad parts 25 and 31 and the sealing part 32 are formed by patterning the said metal film by reactive ion etching etc. using masks (not shown), such as a resist and an oxide film.

  Next, as shown in FIG. 8F, a groove 14 is formed in the semiconductor layer 13 by reactive ion etching or the like using a mask (not shown) such as a resist or an oxide film. Thereby, the 1st board | substrate 10 with which the movable part 20 was formed is prepared.

  Further, in a step different from that shown in FIG. 8, a bonded substrate 41 is prepared as shown in FIG. 9A, and an insulating film 42 is formed on the entire surface of the bonded substrate 41 by thermal oxidation or the like. The bonded substrate 41 is composed of a P-type silicon substrate having a resistivity of 0.01 to 0.03 Ω · cm as described above.

  Next, as shown in FIG. 9B, a metal film is formed on a portion of the insulating film 42 facing the first substrate 10. Then, by patterning the metal film by reactive ion etching or the like using a mask (not shown) such as a resist or an oxide film, the first and second wiring parts 51 and 52, pad parts 53 and 54, sealing A stop 55 is formed.

  Subsequently, as shown in FIG. 10A, the first substrate 10 and the second substrate 40 are bonded. Specifically, alignment is performed by an infrared microscope or the like using appropriately formed alignment marks, and the pad portions 25 and 31 of the first substrate 10, the sealing portion 32, and the pad portions 53 and 54 of the second substrate 40. The sealing part 55 is metal-bonded at 300 to 500 °.

  As a result, the space between the first substrate 10 and the second substrate 40 is sealed by the sealing portion 32 and the sealing portion 55 to form an airtight chamber 90, and the frame portion 22 and the first and second fixed electrodes 51a. , 52a (sensing unit 60) is hermetically sealed in the hermetic chamber 90. Note that the distance between the first substrate 10 and the second substrate 40 is defined by the spacer 33.

  Next, as shown in FIG. 10B, the insulating film 42 and the bonded substrate 41 are ground from the side opposite to the first substrate 10 side, and the insulating film 42 on the side opposite to the first substrate 10 side is removed. At the same time, the bonded substrate 41 is thinned. This step may be performed before the first substrate 10 and the second substrate 40 are bonded.

  Subsequently, as shown in FIG. 10C, the two through holes 70 a are formed by removing the bonded substrate 41 and the insulating film 42 at locations corresponding to the pad portions 53 and 54. Further, in a cross section different from that of FIG. 10C, the bonded substrate 41 and the insulating film 42 are removed at locations corresponding to the first and second lead wirings 51b and 52b in the first and second wiring portions 51 and 52. Thus, two through holes 70a are formed. Then, an insulating film 70b such as TEOS is formed on the wall surface of each through hole 70a. At this time, the insulating film 43 is composed of an insulating film formed on the side of the bonded substrate 41 opposite to the first substrate 10 side. That is, the insulating film 43 and the insulating film 70b are formed in the same process. Thereafter, the insulating film 70b formed at the bottom of each through-hole 70a is removed, and the first and second lead-out wirings 51b and 52b in the first and second wiring parts 51 and 52, and the pad part in each through-hole 70a. 53 and 54 are exposed.

  Next, as shown in FIG. 10D, a metal film is disposed in each through hole 70a by a sputtering method, a vapor deposition method, or the like to form each through electrode 70c. Then, each through electrode 70c is electrically connected to the first and second lead wires 51b and 52b and the pad portions 53 and 54 in the first and second wiring portions 51 and 52, respectively. Thereafter, the through electrode portion 70 is formed by patterning the metal film on the insulating film 43 to form the pad portion 70d.

  The acceleration sensor is manufactured by forming the contact hole 43a in the insulating film 43 and embedding the metal film in the contact hole 43a to form the contact portion 80.

  In addition, although the manufacturing method of one acceleration sensor was demonstrated above, the wafer-like 1st, 2nd board | substrates 10 and 40 are prepared, and after dicing and cutting these, it divides | segments into a chip unit. Also good.

  As described above, the bonded substrate 41 is composed of a P-type silicon substrate having a resistivity of 0.01 to 0.03 Ω · cm. For this reason, the contact resistance between the bonded substrate 41 and the contact portion 80 can be made substantially zero without forming a high concentration layer on the bonded substrate 41 (see FIG. 4). That is, contact resistance can be reduced without increasing the number of manufacturing steps.

  Moreover, the support substrate 11 is comprised with the silicon substrate whose resistivity is 0.01-20 ohm * cm. Therefore, even when a carrier wave is input to the movable portion 20 (semiconductor layer 13) when connected to a fully differential CV conversion circuit, the potential of the support substrate 11 is prevented from varying from part to part. It can suppress and it can suppress that detection accuracy falls.

Further, the semiconductor layer 13 is composed of a P-type silicon substrate having a resistivity of 0.01 to 0.03 Ω · cm, or an N-type silicon substrate having a resistivity of 0.01 to 0.2 Ω · cm. Has been. For this reason, surface resistance (depletion layer resistance) becomes 1.0 Ω · cm ² or less, and it is possible to suppress a decrease in detection accuracy.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, in the first embodiment, the acceleration sensor that detects the acceleration in the z-axis direction has been described as an example. However, the present invention may be applied to an acceleration sensor that detects the acceleration in the x-axis direction or the y-axis direction. it can. In this case, the first substrate 10 is formed with a movable part 20 having a movable electrode that is displaced according to acceleration, and a fixed part having a fixed electrode facing the movable electrode. A carrier wave is input to either the movable electrode or the fixed electrode according to the CV conversion circuit to be connected. Therefore, the support substrate 11 is composed of a silicon substrate having a resistivity of 0.01 to 20 Ω · cm. The physical quantity sensor of the present invention can also be applied to an angular velocity sensor or the like.

  Further, in the first embodiment, a contact portion similar to the contact portion 80 may be formed on the support substrate 11, and the support substrate 11 and an external circuit may be connected to keep the potential of the support substrate 11 constant. In this case, like the bonded substrate 41, the support substrate 11 is formed of a P-type silicon substrate having a resistivity of 0.01 to 0.2 Ω · cm. According to this, it is possible to suppress a variation in parasitic capacitance generated between the semiconductor layer 13 and the support substrate 11 while reducing the contact resistance between the support substrate 11 and the contact portion.

DESCRIPTION OF SYMBOLS 10 1st board | substrate 10a 1 side 40 2nd board | substrate 40a 1 side 41 Bonded board | substrate 60 Sensing part

Claims (6)

A first substrate (10) having one surface (10a);
A second substrate (40) having one surface (40a) and bonded to the first substrate in a state where the one surface faces one surface of the first substrate;
In the physical quantity sensor in which an airtight chamber (90) is formed between the first and second substrates, and a sensing unit (60) that outputs a sensor signal corresponding to the physical quantity is arranged in the airtight chamber,
The second substrate is composed of a P-type silicon substrate having a resistivity of 0.01 to 0.2 [Ω · cm], and is connected to a contact portion (80) configured using a metal material. A physical quantity sensor comprising a bonded substrate (41) maintained at a predetermined potential.   The first substrate is an SOI substrate in which a support substrate (11), an insulating film (12), and a semiconductor layer (13) are sequentially stacked, and the surface of the semiconductor layer opposite to the insulating film is The physical quantity sensor according to claim 1, wherein the physical quantity sensor is one surface of the first substrate. The sensing unit is formed at least in part in the semiconductor layer, and a periodic voltage carrier wave is input to the part.
The physical quantity sensor according to claim 2, wherein the support substrate is formed of a silicon substrate having a potential in a floating state and a resistivity of 0.01 to 20 [Ω · cm].   The support substrate is formed of a P-type silicon substrate having a resistivity of 0.01 to 0.2 [Ω · cm], and is connected to a contact portion formed using a metal material to have a predetermined potential. The physical quantity sensor according to claim 2, wherein the physical quantity sensor is maintained as follows.   The said semiconductor layer is comprised with the P-type silicon substrate whose resistivity is 0.01-0.03 [(ohm) * cm], It is any one of Claim 2 thru | or 4 characterized by the above-mentioned. Physical quantity sensor. 5. The semiconductor layer according to claim 2, wherein the semiconductor layer includes an N-type silicon substrate having a resistivity of 0.01 to 0.2 [Ω · cm]. Physical quantity sensor.

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