JP6020341B2 - Capacitive physical quantity sensor and manufacturing method thereof - Google Patents

Description

  The present invention includes a movable part having a plurality of movable electrodes, and first and second fixed parts having first and second fixed electrodes opposed to the movable electrodes, and is provided between the movable electrode and the first fixed electrode. The present invention relates to a capacitance type physical quantity sensor that detects a physical quantity based on a capacitance and a capacitance difference between a capacitance between a movable electrode and a second fixed electrode, and a method for manufacturing the same.

  Conventionally, as this type of capacitive physical quantity sensor, a sensor using an SOI (Silicon on Insulator) substrate in which a support substrate, an insulating film, and a semiconductor layer are sequentially laminated has been proposed (see, for example, Patent Document 1).

  Specifically, in this capacitive physical quantity sensor, a movable portion having a plurality of movable electrodes that can be displaced in a predetermined direction is formed in a semiconductor layer. Further, the semiconductor layer has a first fixed portion having a first support portion provided with a first fixed electrode facing the movable electrode, and a second support portion provided with a second fixed electrode facing the movable electrode, A second fixed portion is formed on the opposite side of the first fixed portion with the movable portion interposed therebetween. That is, a pair of first and second fixed portions are formed in the semiconductor layer with the movable portion interposed therebetween.

  A recess portion is formed in a portion of the support substrate and the insulating film including a portion facing the movable electrode and the first and second fixed electrodes, and the movable electrode and the first and second fixed electrodes are floated. It is in a state. In order to completely float the first and second fixed electrodes, the first and second support portions including the first and second fixed electrodes are such that the end portion on the movable portion side protrudes partially on the recessed portion. Yes.

  In such a capacitance-type physical quantity sensor, a first capacitance composed of a detection capacitance between the movable electrode and the first fixed electrode and a parasitic capacitance between the first fixed portion and the support substrate is configured. Similarly, a detection capacitor between the movable electrode and the second fixed electrode and a second capacitor composed of a parasitic capacitance between the second fixed portion and the support substrate are configured. Then, the physical quantity is detected based on the difference between the first capacity and the second capacity.

  The size of the parasitic capacitance is proportional to the area of the portion of the first and second fixed portions that is joined to the support substrate via the insulating film. For this reason, the areas of the first and second fixed portions joined to the support substrate are made equal so that the parasitic capacitances are canceled when the difference between the first and second capacitances is calculated.

  The capacitive physical quantity sensor is manufactured as follows, for example. That is, an insulating film is formed on the support substrate, and a depression is formed in the support substrate and the insulating film. Thereafter, a semiconductor layer formed of a silicon substrate or the like is bonded to the insulating film. Then, a mask is formed on the semiconductor layer and the mask is patterned. Subsequently, reactive ion etching (RIE) or the like is performed to form the movable electrode and the first and second fixed electrodes, whereby the capacitive physical quantity sensor is manufactured.

Japanese Patent No. 3435647

  However, in the capacitive physical quantity sensor, when the movable portion and the first and second fixed portions are formed, a positional deviation or the like occurs during mask patterning, and the movable portion and the first and second fixed portions are formed as a whole. There is a case where it deviates from the planned area. For example, in the arrangement direction of the first fixed part, the movable part, and the second fixed part, when the first fixed part, the movable part, and the second fixed part are shifted to the first fixed part side as a whole, the first support is provided. Of the portion, the portion where the end portion on the movable portion side protrudes on the recessed portion becomes smaller. On the other hand, the portion of the second support portion where the end portion on the movable portion side protrudes on the hollow portion is large.

  That is, the area of the first fixed part (first support part) bonded to the support substrate via the insulating film becomes large, and the support substrate via the insulating film of the second fixed part (second support part). The area joined with becomes smaller. That is, the parasitic capacitance formed between the first fixed portion and the support substrate is increased, and the parasitic capacitance formed between the second fixed portion and the support substrate is decreased. For this reason, when calculating the capacitance difference between the first capacitor and the second capacitor, each parasitic capacitor cannot be canceled, and a detection error occurs.

  In order to prevent such a problem from adhering foreign matter to the movable electrode and the first and second fixed electrodes, a cap portion is provided to cover the movable electrode and the first and second fixed electrodes. This also occurs in the capacitive physical quantity sensor. That is, in such a capacitive physical quantity sensor, the cap part is configured by forming an insulating film on a semiconductor substrate, and the semiconductor substrate is bonded to the semiconductor layer via the insulating film. And the hollow part is formed in the part including the part which opposes a movable electrode and a 1st, 2nd fixed electrode among a semiconductor substrate and an insulating film. In addition, parasitic capacitance is formed between the first and second support portions and the semiconductor substrate. For this reason, when the semiconductor substrate (cap portion) and the semiconductor layer are bonded to each other due to misalignment due to misalignment or the like, the area of the portion of the first and second fixing portions to be bonded to the semiconductor substrate (cap portion). Are different from each other in parasitic capacitance.

  In view of the above points, an object of the present invention is to provide a capacitive physical quantity sensor capable of suppressing detection errors and a method for manufacturing the same.

In order to achieve the above object, in the first and third aspects of the invention, the movable portion (20) having a plurality of movable electrodes (24) displaceable in a predetermined direction, and the first fixed facing the movable electrodes. A first fixed part (30) having a first support part (32) provided with an electrode (31); and a second support part (42) provided with a second fixed electrode (41) facing the movable electrode. A first substrate (13, 14) formed with a second fixed part (40) on which the second support part is disposed on the opposite side of the first support part across the movable part, and an insulating film (12, 52) and a second substrate (11, 51) bonded to the first substrate through the insulating film and the second substrate, at least facing the movable electrode and the first and second fixed electrodes in the insulating film. Recesses (17, 54) are formed in the part, and the first support part is connected to the second group via the insulating film. And the area where the second support portion is bonded to the second substrate via the insulating film, the capacitance between the movable electrode and the first fixed electrode, the movable electrode and the first The physical quantity is detected based on the difference between the capacitance between the two fixed electrodes.

In the first aspect of the invention, the second substrate is formed with the first groove portions (18a, 55a) in a portion facing the end portion of the first support portion opposite to the movable portion side, and the second substrate. A second groove portion (18b, 55b) is formed in a portion of the support portion that faces the end opposite to the movable portion side, and the first support portion includes a first connection portion (32a) provided with a first fixed electrode. ) And a first connection portion (32b) for electrically connecting the first connection portion to an external circuit, and the end portion on the movable portion side of the first connection portion protrudes above the recess portion and is first. The end of the connecting part opposite to the movable part protrudes on the first groove part, and the end of the first connecting part on the movable part side does not protrude on the recessed part and is opposite to the movable part of the first connecting part. The end portion of the first connection portion does not protrude above the first groove portion and faces the second substrate at the first connection portion. It is bonded to the second substrate via an insulating film, the second support portion, a second for the second connecting portion to which the second fixed electrode provided (42a), the second connecting portion to an external circuit electrically and a connecting portion (42b), the ends of the movable portion side opposite the second coupling part with protruding movable portion side of the end recess on the second connecting portion protrudes in the second upper groove The end of the second connecting portion on the movable portion side does not protrude above the hollow portion, and the end of the second connecting portion opposite to the movable portion side does not protrude above the second groove portion. The entire surface facing the second substrate is bonded to the second substrate through an insulating film .
In the invention according to claim 3, the second substrate is formed with the first groove portions (18a, 55a) in a portion facing the end portion of the first support portion opposite to the movable portion side, and the second substrate. A second groove (18b, 55b) is formed in a portion of the support portion facing the end opposite to the movable portion side, and at least one first recess (19a) is formed in a portion facing the first support portion. ) And at least one second concave portion (19b) is formed in a portion facing the second support portion, and a part of the end portion on the movable portion side of the first support portion protrudes on the recessed portion. At the same time, a part of the end on the opposite side to the movable part side protrudes on the first groove part, and a part of the end part on the movable part side projects on the recessed part and the second support part is opposite to the movable part side. A part of the end portion on the side protrudes on the second groove portion.

  According to this, since the parasitic capacitance formed between the first support portion and the second substrate is equal to the parasitic capacitance formed between the second support portion and the second substrate, the detection error is suppressed. it can.

A sixth aspect of the present invention is a method of manufacturing a capacitive physical quantity sensor according to any one of the first to fifth aspects, wherein a semiconductor layer is prepared as a first substrate (13), and a second substrate (11 ) Preparing a support substrate, forming a recess in the second substrate, forming the first and second grooves in the second substrate, forming the recess, and the first and second After the step of forming the groove portion, the first substrate is bonded to the surface of the second substrate via the insulating film (12) to form the SOI substrate, and after the step of forming the SOI substrate, the first substrate And forming the movable portion and the first and second fixed portions on the substrate. In the step of forming the movable portion and the first and second fixed portions, one end of the first support portion on the movable portion side is formed. Part protrudes above the recess and part of the end opposite to the movable part is above the first groove. The first fixed part is formed so as to protrude, and a part of the end part on the movable part side in the second support part protrudes on the recessed part and a part of the end part on the opposite side to the movable part side is the first part. By forming the second solid portion so as to protrude on the two groove portions, the area of the portion of the first support portion joined to the second substrate via the insulating film, and the insulating film of the second support portion The area of the portion bonded to the second substrate via the same is made equal.

The invention described in Claim 7 is the method of manufacturing a capacitance type physical quantity sensor according to any one of claims 1 to 5, the insulating film on the support substrate (11) as the first substrate (14) A step of preparing an SOI substrate on which the semiconductor layer (13) is formed via (12) and preparing a semiconductor substrate as the second substrate (51), a movable portion and first and second fixed portions on the first substrate. Forming an insulating film on the second substrate, forming a recess in at least the insulating film of the second substrate and the insulating film, and forming first and second groove portions in the second substrate And a step of bonding the second substrate to the first substrate via the insulating film (52). In the bonding step, a part of the end portion on the movable portion side in the first support portion is a depression. Projecting upward and part of the end opposite to the movable part projecting above the first groove, The first and second portions of the second support portion so that a portion of the end portion on the movable portion side protrudes on the recess portion and a portion of the end portion on the opposite side to the movable portion side protrudes on the second groove portion. By bonding the substrate, the area of the portion of the first support portion that is bonded to the second substrate via the insulating film and the second support portion are bonded to the second substrate via the insulating film. The feature is to make the area of the portion equal.

According to the inventions described in claims 6 and 7 , a part of the end portion on the movable portion side of the first support portion protrudes on the recessed portion, and a portion of the end portion on the opposite side to the movable portion side is the first portion. A part of the end on the movable part side of the second support part protrudes on the recessed part and a part of the end on the opposite side to the movable part side protrudes on the second groove part. I am doing so. For this reason, even if a positional shift occurs, the area of the portion where the first and second support portions are joined to the second substrate via the insulating film does not change, and the parasitic capacitance does not change. For this reason, it can suppress that detection accuracy falls.

  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 a top view of the capacity type physical quantity sensor in a 1st embodiment of the present invention. It is sectional drawing along the II-II line | wire in FIG. It is sectional drawing which shows the manufacturing process of the capacitive physical quantity sensor shown in FIG. 3A is a cross-sectional view of the vicinity of the first support portion when there is no displacement in the process of FIG. 3D, and FIG. 3B is the vicinity of the first support portion when there is a displacement in the process of FIG. FIG. It is sectional drawing of the capacity type physical quantity sensor in 2nd Embodiment of this invention. FIG. 6 is a cross-sectional view of a capacitive physical quantity sensor having a cross section different from that of FIG. 5. It is sectional drawing which shows the manufacturing process of the capacity | capacitance type physical quantity sensor shown in FIG. It is a top view of the capacity type physical quantity sensor in a 3rd embodiment of the present invention. It is sectional drawing equivalent to the IX-IX line in FIG. It is a top view of the capacity type physical quantity sensor in a 4th embodiment of the present invention. It is sectional drawing equivalent to the XI-XI line in FIG. It is sectional drawing of the capacity type physical quantity sensor in 5th Embodiment of this invention. It is sectional drawing of the capacity-type physical quantity sensor in 6th Embodiment of this invention. It is sectional drawing of the capacity type physical quantity sensor in 7th Embodiment of this invention.

  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 of an acceleration sensor having a sensing unit that detects acceleration will be described as an example of a capacitive physical quantity sensor.

  As shown in FIGS. 1 and 2, the acceleration sensor according to the present embodiment includes a support substrate 11, an insulating film 12 disposed on the support substrate 11, and the opposite side of the support substrate 11 across the insulating film 12. An SOI substrate 14 having a semiconductor layer 13 disposed thereon is used.

The support substrate 11 and the semiconductor layer 13 are a silicon substrate or the like, and the insulating film 12 is SiO ₂ or the like. In the present embodiment, the semiconductor layer 13 corresponds to the first substrate of the present invention, and the support substrate 11 corresponds to the second substrate.

  The SOI substrate 14 is subjected to well-known micromachining to form a sensing unit 15. Specifically, the semiconductor layer 13 is formed with a movable portion 20 and first and second fixed portions 30 and 40 each having a comb-shaped beam structure by forming the groove portion 16. A sensing unit 15 that outputs a sensor signal corresponding to the acceleration is formed by the structure.

  And the part corresponding to the formation area of a beam structure among the support substrate 11 and the insulating film 12 is removed, and the hollow part 17 is formed. The depression 17 is for preventing the movable electrode 24 and the first and second fixed electrodes 31 and 41 described later from coming into contact with the support substrate 11 and the insulating film 12.

  The movable part 20 is arranged so as to cross over the hollow part 17, and both ends in the longitudinal direction of the rectangular weight part 21 are integrally connected to the anchor parts 23 a and 23 b via the beam part 22. ing. The anchor portions 23 a and 23 b are supported by the support substrate 11 through the insulating film 12 at the opening edge portion of the recess portion 17. Thereby, the weight part 21 and the beam part 22 are in the state which faced the hollow part 17. FIG.

  Here, each direction of the x-axis, the y-axis, and the z-axis in FIGS. 1 and 2 will be described. 1 and 2, the x-axis direction is the longitudinal direction of the weight portion 21 (up and down direction on the paper surface in FIG. 1). The y-axis direction is a direction perpendicular to the x-axis in the plane of the SOI substrate 14 (the left-right direction in FIG. 1). The z-axis direction is a direction orthogonal to the planar direction of the SOI substrate 14 (the depth direction on the paper surface in FIG. 1).

  The beam portion 22 has a rectangular frame shape in which two parallel beams are connected at both ends thereof, and has a spring function of displacing in a direction perpendicular to the longitudinal direction of the two beams. Specifically, when receiving an acceleration including a component in the x-axis direction, the beam portion 22 displaces the weight portion 21 in the x-axis direction and restores the original state according to the disappearance of the acceleration. ing. Therefore, the weight portion 21 connected to the support substrate 11 through such a beam portion 22 can be displaced in the displacement direction (x-axis direction) of the beam portion 22 on the recess portion 17 in accordance with the application of acceleration. It has become.

  Further, the movable portion 20 includes a plurality of movable electrodes 24 that are integrally projected in opposite directions from both side surfaces of the weight portion 21 in a direction (y-axis direction) orthogonal to the longitudinal direction of the weight portion 21. ing. In FIG. 1, four movable electrodes 24 are formed on the left side and the right side of the weight part 21 so as to face the hollow part 17. Each movable electrode 24 is formed integrally with the weight portion 21 and the beam portion 22, and can be displaced in the x-axis direction together with the weight portion 21 when the beam portion 22 is displaced.

  The first and second fixing portions 30 and 40 are supported by the support substrate 11 via the insulating film 12 at portions other than the portions where the anchor portions 23a and 23b are supported in the opening edge portion of the recess portion 17. Yes. That is, the first and second fixed portions 30 and 40 are arranged so as to sandwich the movable portion 20. In FIG. 1, the first fixed unit 30 is disposed on the left side of the sheet with respect to the movable unit 20, and the second fixed unit 40 is disposed on the right side of the sheet with respect to the movable unit 20. The first and second fixing portions 30 and 40 are electrically independent from each other.

  In addition, the first and second fixed portions 30 and 40 are a plurality of first and second fixed electrodes 31 and 41 disposed to face each other in parallel with the side surface of the movable electrode 24 so as to have a predetermined detection interval. The first and second support portions 32 and 42 are supported by the support substrate 11 via the insulating film 12.

  Four first and second fixed electrodes 31 and 41 are formed in FIG. 1, and are arranged in a comb shape so as to engage with a gap between comb teeth in the movable electrode 24. And it is in the state which faced the hollow part 17 by being supported by each support part 32 and 42 in the shape of a cantilever.

  The first support part 32 includes a first connection part 32a provided with the first fixed electrode 31, and a first connection part 32b for electrically connecting the first connection part 32a to an external circuit. The second support part 42 includes a second connection part 42a provided with the second fixed electrode 41, and a second connection part 42b for electrically connecting the second connection part 42a to an external circuit. .

  In the present embodiment, the first and second connecting portions 32a and 42a are formed in a planar rectangular shape whose long side is parallel to the longitudinal direction (x-axis direction) of the weight portion 21, and each end on the movable portion 20 side. The part includes first and second fixed electrodes 31 and 41. And the edge part by the side of the movable part 20 among the 1st, 2nd connection parts 32a and 42a protrudes on the hollow part 17, respectively.

  The first and second connection portions 32b and 42b are connected to the first and second connection portions 32a and 42a, respectively, and predetermined portions of the first and second connection portions 32b and 42b are bonded wires (not shown) or the like. Via an external circuit.

  The movable part 20 has an anchor part 23b electrically connected to an external circuit via a bonding wire (not shown) or the like. Similarly, the peripheral portion 60 located around the movable portion 20, the first and second fixed portions 30, 40 with the groove portion 16 therebetween is also electrically connected to an external circuit via a bonding wire (not shown). ing.

  Further, in the support substrate 11 and the insulating film 12, a first groove portion 18 a is formed in a portion of the first coupling portion 32 a that faces the end portion on the opposite side to the movable portion 20 side. Similarly, in the support substrate 11 and the insulating film 12, a second groove portion 18b is formed in a portion of the second coupling portion 42a that faces the end portion on the opposite side to the movable portion 20 side.

  Specifically, the first and second groove portions 18a and 18b are extended in the direction (x-axis direction) along the boundary between the first and second coupling portions 32a and 42a and the opening in the recess portion 17. Yes.

  And as for the 1st, 2nd connection parts 32a and 42a, the edge part on the opposite side to the movable part 20 side protrudes on the 1st, 2nd groove parts 18a and 18b, respectively. More specifically, the first connecting portion 32a has a first connecting portion 32a (first support) having a direction and a length of a boundary between the first connecting portion 32a (first supporting portion 32) and the opening in the first groove portion 18a. Part 32) and the opening of the hollow part 17 so that the direction and the length of the boundary are equal to each other, and protrudes on the first groove part 18a. Similarly, the direction and length of the boundary between the second connection portion 42a (second support portion 42) and the opening in the second groove portion 18b are the same as the second connection portion 42a (second support portion 42a). 42) and the direction of the boundary between the opening portion in the recess portion 17 and the length thereof are equal to each other so as to protrude on the second groove portion 18b.

  Note that “the length of the boundary is equal to the length” includes a slight miscalculation caused by a manufacturing error or the like in addition to the case where the lengths are completely coincident.

  The first and second support portions 32 and 42 including the first and second connecting portions 32 a and 42 a and the first and second connection portions 32 b and 42 b are joined to the support substrate 11 via the insulating film 12. The areas of the parts (the areas of the opposing parts) are equal to each other. That is, the parasitic capacitance formed between the first support portion 32 and the support substrate 11 and the parasitic capacitance formed between the second support portion 42 and the support substrate 11 are made equal.

  Note that “the areas are equal” includes a slight error caused by a manufacturing error or the like in addition to the case where they completely coincide.

  That is, in the capacitive physical quantity sensor according to the present embodiment, the detection capacitance formed between the movable electrode 24 and the first fixed electrode 31 and the parasitic capacitance formed between the first support portion 32 and the support substrate 11. The 1st capacity | capacitance consisting of these is comprised. Similarly, a second capacitor including a detection capacitor formed between the movable electrode 24 and the second fixed electrode 41 and a parasitic capacitor formed between the second support portion 42 and the support substrate 11 is configured. ing. When acceleration is applied in the x-axis direction, the entire movable part 20 excluding the anchor parts 23a and 23b is integrally displaced in the x-axis direction by the spring function of the beam part 22, and according to the displacement of the movable electrode 24 The detection capacity changes.

  The above is the configuration of the capacitive physical quantity sensor in the present embodiment. In such a capacitive physical quantity sensor, acceleration is detected based on a difference in capacitance between the first capacitor and the second capacitor. At this time, the parasitic capacitance included in the first capacitor and the parasitic capacitance included in the second capacitor are equalized as described above. For this reason, when the capacitance difference between the first capacitor and the second capacitor is calculated, the mutual parasitic capacitance is canceled, and the detection error can be suppressed.

  Next, a manufacturing method of the capacitive physical quantity sensor will be described with reference to FIG.

  First, as shown in FIG. 3A, the insulating film 12 is formed on the support substrate 11. Next, as shown in FIG. 3B, a mask (not shown) such as a resist or an oxide film is formed on the insulating film 12 to form the depressions 17 and the first and second groove portions 18a and 18b. The mask is patterned so that the predetermined area is opened. Subsequently, for example, the insulating film 12 and the support substrate 11 are etched by RIE or the like to form the recessed portion 17 and the first and second groove portions 18a and 18b.

  Subsequently, as shown in FIG. 3C, the insulating film 12 and the semiconductor layer 13 are joined to form the SOI substrate 14. 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 surface (bonding surface) of the insulating film 12 and the surface (bonding surface) of the semiconductor layer 13 are irradiated with N ₂ plasma, O ₂ plasma, or Ar ion beam, and each surface (bonding) of the insulating film 12 and the semiconductor layer 13 is bonded. The surface).

  Next, alignment is performed by an infrared microscope or the like using an appropriately formed alignment mark, and the insulating film 12 and the semiconductor layer 13 are bonded by so-called direct bonding at a low temperature of room temperature to 550 ° C.

  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 or intermediate layer bonding. Further, after the joining, a treatment for improving the joining quality such as high temperature annealing may be performed. Further, after bonding, the semiconductor layer 13 may be processed to a desired thickness by grinding and polishing.

  Thereafter, as shown in FIG. 3D, a mask (not shown) such as a resist or an oxide film is formed on the semiconductor layer 13, and the mask is patterned so that a region where the groove 16 is to be formed is opened. . Subsequently, for example, the semiconductor layer 13 is etched by RIE or the like to form the groove 16. Thereby, the movable part 20 and the first and second fixed parts 30 and 40 are formed, and the capacitive physical quantity sensor is manufactured.

  When forming the first fixed portion 30, the end portion on the movable portion 20 side of the first connecting portion 32 a protrudes on the recessed portion 17, and the end portion on the opposite side to the movable portion 20 side is the first end portion. The 1st fixing | fixed part 30 is formed so that it may protrude on the 1 groove part 18a. Similarly, when the second fixed portion 40 is formed, the end portion on the movable portion 20 side of the second coupling portion 42a protrudes on the recessed portion 17 and the end portion on the opposite side to the movable portion 20 side is formed. The second fixing portion 40 is formed so as to protrude on the second groove portion 18b.

  At this time, for example, a positional shift of about several μm occurs when patterning the mask, and the movable portion 20 and the first and second fixed portions 30 and 40 are entirely on the first fixed portion 30 side (y-axis direction). May be misaligned. In this case, as shown in FIG. 4 (b), the length a of the portion of the first connecting portion 32a that protrudes above the recess portion 17 is shortened, and the length b of the portion that protrudes into the first groove portion 18a is become longer.

  However, the sum of the lengths of the first connecting portions 32a projecting into the depressions 17 and the first groove portions 18a is not misaligned (FIG. 4A) and misaligned. (FIG. 4B) is the same. That is, the area of the portion of the first connecting portion 32a that is bonded to the support substrate 11 via the insulating film 12 (the area of the portion facing the support substrate 11) does not change, and the first connecting portion 32a and the support substrate are not changed. 11 does not change. Similarly, although not particularly illustrated, even if a positional deviation occurs, the sum of the lengths of the portions of the second connecting portion 42a protruding into the recessed portion 17 and the second groove portion 18b does not change, and the second connecting portion 42a. And the parasitic capacitance formed between the support substrate 11 and the support substrate 11 do not change. That is, even if the positional deviation occurs as described above by providing the length (width) of the first and second groove portions 18a and 18b in the y-axis direction larger in advance than the positional deviation amount that can occur in manufacturing, It can suppress that a parasitic capacitance changes.

  For this reason, by manufacturing the capacitive physical quantity sensor as described above, it is possible to provide a capacitive physical quantity sensor in which the parasitic capacitance does not change even if a positional deviation occurs.

  As described above, in the capacitive physical quantity sensor of the present embodiment, the first and second groove portions 18a and 18b are formed, and the first and second support portions 32 and 42 are partially recessed portions 17 respectively. And it protrudes on the 1st, 2nd groove part 18a, 18b. And the area of the part joined to the support substrate 11 via the insulating film 12 (the area of the part which opposes) is made mutually equal. For this reason, the parasitic capacitance formed between the 1st, 2nd support parts 32 and 42 and the support substrate 11 becomes equal, and a detection error can be suppressed.

  Further, when manufacturing the capacitive physical quantity sensor, the first groove portion 18a is formed, and the end portion on the movable portion 20 side of the first connecting portion 32 protrudes on the recessed portion 17, and the movable portion 20 side The 1st fixing | fixed part 30 is formed so that the edge part on the opposite side may protrude on the 1st groove part 18a. Then, the second groove portion 18b is formed, and the end portion on the movable portion 20 side of the second connecting portion 42a protrudes on the recessed portion 17, and the end portion on the opposite side to the movable portion 20 side is on the second groove portion 18b. The second fixing portion 40 is formed so as to protrude in the direction.

  For this reason, even when the movable part 20 and the first and second fixed parts 30 and 40 are entirely displaced in the y-axis direction when the movable part 20 and the first and second fixed parts 30 and 40 are formed, Of the first and second support portions 32 and 42, the area of the portion joined to the support substrate 11 via the insulating film 12 (the area of the portion facing the support substrate 11) does not change. That is, the parasitic capacitance formed between the first and second support portions 32 and 42 and the support substrate 11 does not change. Therefore, even if a positional deviation occurs, a capacitive physical quantity sensor that can suppress detection errors without changing the parasitic capacitance can be manufactured.

  In the above description, the positional deviation in the y-axis direction has been described as an example. However, even if a positional deviation in the rotational direction around the x-axis direction and the z-axis that may occur in manufacturing occurs, according to the present embodiment. Thus, it is possible to manufacture a capacitive physical quantity sensor that can suppress the detection error without changing the parasitic capacitance.

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, a cap portion is bonded to the semiconductor layer 13 with respect to the first embodiment, and the other aspects are the same as those in the first embodiment, and thus the description thereof is omitted here.

  As shown in FIGS. 5 and 6, in the present embodiment, in order to prevent water or foreign matter from adhering to the sensing unit 15, the cap unit is hermetically sealed to the semiconductor layer 13. 50 is provided. 5 is a cross-sectional view corresponding to the II-II line in FIG. 1, and the cap portion 50 is a cross-sectional view of a portion corresponding to the II-II line. 6 is a cross-sectional view corresponding to the VI-VI line in FIG. 1, and the cap portion 50 is a cross-sectional view of a portion corresponding to the VI-VI line.

  The cap unit 50 is configured by forming an insulating film 52 on one surface 51 a of the semiconductor substrate 51 and forming an insulating film 53 on the other surface 51 b, and the insulating film 52 is bonded to the semiconductor layer 13. A recess 54 is formed in a portion of the semiconductor substrate 51 and the insulating film 52 facing the movable electrode 24 and the first and second fixed electrodes 31 and 41. The recessed portion 54 prevents the movable electrode 24 and the first and second fixed electrodes 31 and 41 from coming into contact with the semiconductor substrate 51 and the insulating film 52, as in the recessed portion 17.

  In the present embodiment, the semiconductor layer 13 corresponds to the first substrate, and the support substrate 11 and the semiconductor substrate 51 correspond to the second substrate. In other words, it can be said that the capacitive physical quantity sensor of the present embodiment has a first substrate disposed between two second substrates.

  The semiconductor substrate 51 and the insulating film 52 have a first groove portion 55a formed in a portion of the first connecting portion 32a that faces the end opposite to the movable portion 20 side, and the second connecting portion 42a Of these, the second groove 55b is formed in a portion facing the end opposite to the movable portion 20 side.

  Specifically, the first and second groove portions 55a and 55b are extended in a direction (x-axis direction) along the boundary between the first and second coupling portions 32a and 42a and the opening in the recess portion 54. Yes.

  Further, the first and second connecting portions 32a and 42a have end portions on the opposite side to the movable portion 20 projecting from the first and second groove portions 55a and 55b. More specifically, the first connecting portion 32a has a first connecting portion 32a (first support) having a direction and length of a boundary between the first connecting portion 32a (first supporting portion 32) and the opening in the first groove portion 55a. Part 32) and the opening in the recessed part 54 so as to be equal to the direction and length of the boundary, and protrudes on the first groove part 55a. Similarly, the direction and length of the boundary between the second connection portion 42a (second support portion 42) and the opening in the second groove portion 55b are the same as the second connection portion 42a (second support portion 42a). 42) and the direction of the boundary between the opening portion in the recessed portion 54 and the length thereof are the same so as to protrude on the second groove portion 55b.

  The first and second connecting portions 32a and 42a have the same area (the area of the opposing portion) of the portion bonded to the semiconductor substrate 51 through the insulating film 52. That is, the parasitic capacitance formed between the first connection portion 32a and the semiconductor substrate 51 is equal to the parasitic capacitance formed between the second connection portion 42a and the semiconductor substrate 51.

  In addition, four through electrode portions 56 that penetrate the cap portion 50 in the stacking direction of the SOI substrate 14 and the cap portion 50 are formed in the cap portion 50. Specifically, each through electrode portion 56 includes a hole portion 56a penetrating the insulating film 53, the semiconductor substrate 51, and the insulating film 52, an insulating film 56b formed on the wall surface of the hole portion 56a, and the insulating film 56b. And a pad 56d.

  One of the four through electrode portions 56 is electrically connected to the anchor portion 23b. Also, two of the four through electrode portions 56 are electrically connected to the first and second connection portions 32b and 42b, respectively. One of the four through electrode portions 56 is electrically connected to the peripheral portion 60.

  In FIG. 6, the hole portion 56 a is illustrated as having a conical shape, but the hole portion 56 a may be formed into a cylindrical shape or a rectangular tube shape. For example, an insulating material such as TEOS is used as the insulating film 56b, and Al or the like is used as the through electrode 56c and the pad 56d.

  Furthermore, in this embodiment, the electrode 57a and the pad 57b are formed so that the semiconductor substrate 51 and an external circuit can be electrically connected. More specifically, the electrode 57 a is formed so as to be connected to the semiconductor substrate 51 through a contact hole 53 a formed in the insulating film 53. The pad 57b is formed on the insulating film 53.

  A protective film 58 is formed on the insulating film 53, the through electrode 56c, the pad 56d, the electrode 57a, and the pad 57b. A contact hole 58a that exposes the pads 56d and 57b is formed in the protective film 58. Yes. Thereby, electrical connection between the pads 56d and 57b and the external circuit can be achieved.

  The above is the configuration of the capacitive physical quantity sensor in the present embodiment. Next, a method for manufacturing such a capacitive physical quantity sensor will be described.

  First, as shown in FIG. 7A, an insulating film 52 is formed on one surface 51 a of the semiconductor substrate 51. Then, as shown in FIG. 7B, a mask (not shown) such as a resist or an oxide film is formed on the insulating film 52, and the recess 54 and the first and second groove portions 55a and 55b are to be formed. The mask is patterned so that the region is opened. Subsequently, for example, the insulating film 52 and the semiconductor substrate 51 are etched by RIE or the like to form the recessed portion 54 and the first and second groove portions 55a and 55b.

  3 is prepared, and the semiconductor layer 13 and the insulating film 52 are bonded together as shown in FIG. 7C.

  Specifically, the end portion on the movable portion 20 side of the first connecting portion 32a protrudes on the recessed portion 54, and the end portion on the opposite side to the movable portion 20 side protrudes on the first groove portion 55a. The semiconductor layer 13 and the insulating film 52 are bonded. In addition, the end of the second connecting portion 42a on the movable portion 20 side protrudes on the recessed portion 54, and the end on the opposite side to the movable portion 20 side protrudes on the second groove portion 55b. And the insulating film 52 are bonded.

  At this time, misalignment due to misalignment or the like occurs, and the movable unit 20 and the first and second fixed units 30 and 40 may be displaced in the y-axis direction as a whole. However, since the first and second groove portions 55a and 55b are formed in the same manner as described above, the sum of the lengths of the portions of the first connecting portion 32a protruding into the recessed portion 54 and the first groove portion 55a is changed. However, the parasitic capacitance formed between the first connecting portion 32a and the support substrate 11 does not change. Similarly, the sum of the lengths of the portions of the second connecting portion 42a that protrude into the recessed portion 17 and the second groove portion 18b does not change, and the parasitic capacitance formed between the second connecting portion 42a and the support substrate 11. Does not change.

  Subsequently, although not particularly shown, four holes are formed by etching and removing the semiconductor substrate 51 and the insulating film 52 at locations corresponding to the anchor portion 23b, the first and second connection portions 32b and 42b, and the peripheral portion 60. A portion 56a is formed. Thereafter, an insulating film 56b such as TEOS is formed on the wall surface of each hole 56a. At this time, the insulating film 53 is configured by the insulating film formed on the other surface 51 b of the semiconductor substrate 51. Subsequently, the insulating film 56b formed at the bottom of each hole 56a is removed, and the semiconductor layer 13 is exposed. At the same time, part of the insulating film 53 is removed to form a contact hole 53a that partially exposes the other surface 51b of the semiconductor substrate 51.

  Next, a metal such as Al or Al-Si is formed in the hole 56a by sputtering or vapor deposition to form the through electrode 56c. Each through electrode 56c, the anchor 23b, the first and second connection parts 32b are formed. , 42b and the peripheral portion 60 are electrically connected to each other. At this time, the electrode 57a is also formed at the same time. Then, the metal on the insulating film 53 is patterned to form pads 56d and 57b.

  Thereafter, the protective film 58 is formed by CVD or the like, and the contact hole 58a is formed by etching or the like, whereby the capacitive physical quantity sensor of this embodiment is manufactured.

  As described above, in the present embodiment, the cap unit 50 is provided, and it is possible to prevent water, foreign matter, and the like from adhering to the sensing unit 15. In addition, since the first and second groove portions 55a and 55b are formed in the semiconductor substrate 51, the first support is provided even when misalignment occurs due to misalignment or the like when the semiconductor layer 13 and the insulating film 52 are joined. The parasitic capacitance formed between the portion 32 and the semiconductor substrate 51 and the parasitic capacitance formed between the second support portion 42 and the semiconductor substrate 51 do not change. For this reason, a detection error can be suppressed.

(Third embodiment)
A third embodiment of the present invention will be described. In the present embodiment, the first and second recesses are formed in the support substrate 11 and the insulating film 12 with respect to the first embodiment, and the other aspects are the same as those in the first embodiment. Omitted.

  As shown in FIGS. 8 and 9, in the present embodiment, two first recesses 19 a are formed in a portion of the support substrate 11 and the insulating film 12 that faces the first coupling portion 32 a. In addition, two second recesses 19b having the same size as the first recesses 19a are formed in portions of the support substrate 11 and the insulating film 12 that face the second connection portions 42a.

  In the present embodiment, the first recess 19a is formed to communicate the recess 17 and the first groove 18a, and the second recess 19b is formed to communicate the recess 17 and the second groove 18b. Has been.

  In such a capacitive physical quantity sensor, the parasitic capacitance formed between the first connecting portion 32a and the support substrate 11 and the parasitic capacitance formed between the second connecting portion 42a and the support substrate 11 are large. You can make it smaller. For this reason, the original SN ratio (signal noise ratio) can be increased.

  In addition, although what demonstrated the 2nd 1st recessed part 19a and the 2nd recessed part 19b was demonstrated here, the 1st recessed part 19a and the 2nd recessed part 19b may be only one, and more are formed. It may be.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. In the present embodiment, the first and second connecting portions 32a and 42a are formed with the first and second holes with respect to the first embodiment, and the others are the same as the first embodiment. The description is omitted here.

  As shown in FIGS. 10 and 11, in the present embodiment, two first and second hole portions 71 and 72 having the same size are formed in the first and second connection portions 32a and 42a, respectively. ing. Specifically, the two first hole portions 71 are formed from a portion located on the recessed portion 17 to a portion located on the first groove portion 18a in the first connecting portion 32a. The two second hole portions 72 are formed from a portion located on the recessed portion 17 to a portion located on the second groove portion 18b in the second connecting portion 42a.

  In such a capacitive physical quantity sensor, as in the third embodiment, the size of each parasitic capacitance itself can be reduced. For this reason, the original signal-to-noise ratio (S / N ratio) can be increased.

  In addition, when the said physical quantity sensor forms the groove part 16, the 1st, 2nd hole parts 71 and 72 covering the part located on the 1st, 2nd groove parts 18a and 18b from the part located on the hollow part 17 are provided. Manufactured by forming.

  In addition, although what demonstrated the 2nd 1st hole part 71 and the 2nd hole part 72 was demonstrated here, the 1st hole part 71 and the 2nd hole part 72 may be only one, A plurality of them may be formed.

(Fifth embodiment)
A fifth embodiment of the present invention will be described. In the present embodiment, the shape of the recessed portion 17 and the first and second groove portions 18a and 18b is changed with respect to the second embodiment, and the other aspects are the same as those of the first embodiment. Is omitted.

  As shown in FIG. 12, in this embodiment, the recess 17 and the first and second groove portions 18 a and 18 b are formed only in the insulating film 12. Even in such a capacitive physical quantity sensor, since the first and second groove portions 18a, 18b, 55a, and 55b are formed, the same effects as in the second embodiment can be obtained.

(Sixth embodiment)
A sixth embodiment of the present invention will be described. In the present embodiment, the shape of the recessed portion 54 and the first and second groove portions 55a and 55b is changed with respect to the second embodiment, and the other aspects are the same as those of the first embodiment. Is omitted.

  As shown in FIG. 13, in this embodiment, the recessed portion 54 and the first and second groove portions 55 a and 55 b are formed only in the insulating film 52. Even in such a capacitive physical quantity sensor, since the first and second groove portions 18a, 18b, 55a, and 55b are formed, the same effects as in the second embodiment can be obtained.

(Seventh embodiment)
A seventh embodiment of the present invention will be described. In the present embodiment, the shapes of the recessed portions 17 and 54 and the first and second groove portions 18a, 18b, 55a, and 55b are changed with respect to the second embodiment, and the other aspects are the same as those of the first embodiment. Therefore, the description is omitted here.

  As shown in FIG. 12, in this embodiment, the recess 17 and the first and second groove portions 18 a and 18 b are formed only in the insulating film 12. The recess 54 and the first and second groove portions 55 a and 55 b are formed only in the insulating film 52.

  Even in such a capacitive physical quantity sensor, since the first and second groove portions 18a, 18b, 55a, and 55b are formed, the same effects as in the second embodiment can be obtained.

(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.

  That is, in each of the above-described embodiments, the acceleration sensor in which the sensing unit 15 for detecting acceleration is formed as an example of the capacitive physical quantity sensor. However, the present invention detects a physical quantity using a capacitance difference. Can be applied. For example, the present invention can be applied to an angular velocity sensor that detects an angular velocity based on a capacity difference or a pressure sensor that detects pressure.

  Moreover, the said 3rd Embodiment can also be combined with the said 2nd, 5th-7th embodiment. That is, in the capacitive physical quantity sensor including the cap unit 50, the first and second recesses 19 a and 19 b may be formed in the support substrate 11 and the insulating film 12. In this case, although not particularly illustrated, the first and second recesses corresponding to the first and second recesses 19 a and 19 b may be formed in the semiconductor substrate 51 and the insulating film 52. And the said 4th Embodiment can also be combined with the said 2nd, 5th-7th embodiment. That is, in the capacitive physical quantity sensor including the cap portion 50, the first and second hole portions 71 and 72 may be formed in the first and second connection portions 32a and 42a. Furthermore, you may combine the said 2nd-4th embodiment suitably.

  In the second, fifth to seventh embodiments, the recess 17 may be formed only in the insulating film 12, and the first and second groove portions 18a and 18b may not be formed. In this case, the SOI substrate 14 corresponds to the first substrate of the present invention, and the cap portion 50 corresponds to the second substrate of the present invention.

DESCRIPTION OF SYMBOLS 11 Support substrate 12 Insulating film 13 Semiconductor layer 14 SOI substrate 17, 54 Depression part 18a, 18b 1st, 2nd groove part 20 Movable part 24 Movable electrode 30, 40 1st, 2nd fixed part 31, 41 1st, 2nd Fixed electrode 32, 42 1st, 2nd support part 32a, 42a 1st, 2nd support part 51 Semiconductor substrate 52 Insulating film 55a, 55b 1st, 2nd groove part

Claims (7)

A movable part (20) having a plurality of movable electrodes (24) displaceable in a predetermined direction, and a first support part (32) provided with a first fixed electrode (31) facing the movable electrode. And a second support part (42) provided with a first fixed part (30) and a second fixed electrode (41) facing the movable electrode, the second support part sandwiching the movable part and the second support part (42). A first substrate (13, 14) formed with a second fixing portion (40) disposed on the opposite side of the one support portion;
A second substrate (11, 51) bonded to the first substrate via an insulating film (12, 52),
A depression (17, 54) is formed in a portion of the insulating film and the second substrate facing at least the movable electrode and the first and second fixed electrodes in the insulating film,
An area where the first support portion is bonded to the second substrate via the insulating film is equal to an area where the second support portion is bonded to the second substrate via the insulating film. ,
In a capacitive physical quantity sensor that detects a physical quantity based on a difference between a capacity between the movable electrode and the first fixed electrode and a capacity between the movable electrode and the second fixed electrode,
In the second substrate, first groove portions (18a, 55a) are formed in a portion of the first support portion that faces the end portion on the opposite side to the movable portion side, and the second support portion has the movable portion side. The second groove (18b, 55b) is formed in the portion facing the end opposite to the side,
The first support part includes a first connection part (32a) provided with the first fixed electrode, and a first connection part (32b) for electrically connecting the first connection part to an external circuit. the projecting opposite end portions of the first upper groove and the movable portion side of the first connecting portion with the end portion of the movable portion side of the first connecting portion protrudes on the recess portion, the first The end portion on the movable portion side in one connection portion does not protrude on the recess portion, and the end portion on the opposite side to the movable portion in the first connection portion does not protrude on the first groove portion, The entire surface of the connecting portion facing the second substrate is bonded to the second substrate via the insulating film,
The second support part includes a second connection part (42a) provided with the second fixed electrode, and a second connection part (42b) for electrically connecting the second connection part to an external circuit. The end of the second connecting part on the movable part side protrudes on the recessed part, and the end of the second connecting part on the side opposite to the movable part side protrudes on the second groove part . The end portion on the movable portion side in the two connection portions does not protrude on the recess portion, and the end portion on the opposite side to the movable portion side in the second connection portion does not protrude on the second groove portion, A capacitive physical quantity sensor, wherein an entire surface of the second connection portion facing the second substrate is bonded to the second substrate through the insulating film . In the second substrate, at least one first recess (19a) is formed in a portion facing the first support portion, and at least one second recess (19b) is formed in a portion facing the second support portion. The capacitive physical quantity sensor according to claim 1, wherein the capacitive physical quantity sensor is formed. A movable part (20) having a plurality of movable electrodes (24) displaceable in a predetermined direction, and a first support part (32) provided with a first fixed electrode (31) facing the movable electrode. And a second support part (42) provided with a first fixed part (30) and a second fixed electrode (41) facing the movable electrode, the second support part sandwiching the movable part and the second support part (42). A first substrate (13, 14) formed with a second fixing portion (40) disposed on the opposite side of the one support portion;
A second substrate (11, 51) bonded to the first substrate via an insulating film (12, 52),
A depression (17, 54) is formed in a portion of the insulating film and the second substrate facing at least the movable electrode and the first and second fixed electrodes in the insulating film,
An area where the first support portion is bonded to the second substrate via the insulating film is equal to an area where the second support portion is bonded to the second substrate via the insulating film. ,
In a capacitive physical quantity sensor that detects a physical quantity based on a difference between a capacity between the movable electrode and the first fixed electrode and a capacity between the movable electrode and the second fixed electrode,
In the second substrate, first groove portions (18a, 55a) are formed in a portion of the first support portion that faces the end portion on the opposite side to the movable portion side, and the second support portion has the movable portion side A second groove (18b, 55b) is formed in a portion facing the end opposite to the first portion, and at least one first recess (19a) is formed in a portion facing the first support portion, At least one second recess (19b) is formed in a portion facing the second support portion,
In the first support part, a part of the end part on the movable part side protrudes on the recess part and a part of the end part on the opposite side to the movable part side protrudes on the first groove part,
In the second support part, a part of the end part on the movable part side protrudes on the recess part, and a part of the end part on the opposite side to the movable part side protrudes on the second groove part. Capacitive physical quantity sensor characterized by The direction and length of the boundary line between the opening in the first groove and the first support are made equal to the direction and length of the boundary between the opening in the recess and the first support,
The direction and length of the boundary line between the opening in the second groove and the second support are made equal to the direction and length of the boundary between the opening in the recess and the second support. capacitive physical quantity sensor according to any one of claims 1 to 3, characterized in that there. The first support portion is formed with at least one first hole (71) removed from a portion located on the recess portion to a portion located on the first groove portion,
The second support portion is formed with at least one second hole portion (72) removed from a portion located on the recess portion to a portion located on the second groove portion. The capacitive physical quantity sensor according to any one of claims 1 to 4 . In the manufacturing method of the capacitive physical quantity sensor according to any one of claims 1 to 5 ,
Preparing a semiconductor layer as the first substrate (13) and preparing a support substrate as the second substrate (11);
Forming the recess in the second substrate;
Forming the first and second groove portions on the second substrate;
After the step of forming the recess and the step of forming the first and second groove portions , the SOI substrate is bonded to the surface of the second substrate via the insulating film (12). Forming a step;
After the step of forming the SOI substrate, the step of forming the movable portion and the first and second fixed portions on the first substrate,
In the step of forming the movable portion and the first and second fixed portions, a part of the end portion on the movable portion side of the first support portion protrudes on the hollow portion and is opposite to the movable portion side. The first fixed portion is formed so that a part of the end portion of the second support portion protrudes on the first groove portion, and a part of the end portion on the movable portion side of the second support portion protrudes on the recess portion. And forming the second fixing portion so that a part of the end portion on the opposite side to the movable portion side protrudes on the second groove portion, so that the insulating film is interposed in the first support portion. Capacitance type characterized in that the area of the portion bonded to the second substrate is made equal to the area of the second support portion bonded to the second substrate via the insulating film Manufacturing method of physical quantity sensor. In the manufacturing method of the capacitive physical quantity sensor according to any one of claims 1 to 5 ,
An SOI substrate in which a semiconductor layer (13) is formed on a support substrate (11) via an insulating film (12) is prepared as the first substrate (14), and a semiconductor substrate is prepared as the second substrate (51). And a process of
Forming the movable portion and the first and second fixed portions on the first substrate;
Forming the insulating film on the second substrate;
Forming the recess in at least the insulating film of the second substrate and the insulating film;
Forming the first and second groove portions on the second substrate;
Bonding the second substrate to the first substrate through the insulating film (52),
In the joining step, a part of the end part on the movable part side of the first support part protrudes on the recess part and a part of the end part on the opposite side to the movable part side is on the first groove part. And a part of the end of the second support part on the side of the movable part protrudes on the recess part and a part of the end part on the opposite side to the side of the movable part is on the second groove part. By bonding the first and second substrates so as to protrude, the area of the portion of the first support portion that is bonded to the second substrate via the insulating film, and the second support portion Of these, the area of the portion bonded to the second substrate through the insulating film is made equal to each other.

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