JP2013178182A - Capacitive physical quantity sensor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitive physical quantity sensor and a manufacturing method thereof, which can obtain excellent sealability and excellent sensitivity while reducing a parasitic capacitance.SOLUTION: A capacitive physical quantity sensor 1 comprises: a sensor substrate 11 for detecting a physical quantity; a base substrate 12 bonded to the sensor substrate 11; and an insulating layer 13 for bonding the sensor substrate 11 and the base substrate 12. The sensor substrate 11 includes a movable part 14 which enables a displacement, and a peripheral part 15 which is located around the movable part 14 and which is bonded through the base substrate 12 and the insulating layer 13. The physical quantity can be detected on the basis of a change in capacitance between the movable part 14 and the base substrate 12, and the insulating layer 13 includes a projection 16 projecting in a direction away from the base substrate 12, and the entire projection 16 is covered with the peripheral part 15.

Description

  The present invention relates to a capacitance type physical quantity sensor having a movable part that can be displaced in the height direction, and more particularly, to a capacitance type physical quantity sensor that reduces parasitic capacitance.

  In Patent Document 1, as shown in FIG. 15, a third silicon substrate 501 having a lower diaphragm 506 and a fourth silicon substrate 502 having an upper diaphragm 507 include a second insulating layer 503, a fifth silicon substrate 505, and a third silicon substrate 505. A capacitive pressure sensor bonded via an insulating layer 504 is disclosed.

  This capacitive pressure sensor is manufactured as follows. After the second insulating layer 503 is applied on the surface of the third silicon substrate 501 and the second insulating layer 503 is patterned, the fifth silicon substrate 505 is bonded onto the second insulating layer 503.

  Next, the fifth silicon substrate 505 is patterned, and a third insulating layer 504 is formed on the surface of the fifth silicon substrate 505. Then, the third insulating layer 504 is patterned, and the fourth silicon substrate 502 is bonded onto the third insulating layer 504.

  Next, a resist layer is formed on the surface of the third silicon substrate 501 and the fourth silicon substrate 502, and wet etching is performed using the resist layer as a mask.

JP-A-11-211597

  The capacitance-type pressure sensor disclosed in Patent Document 1 has a capacitance between the lower diaphragm 506 and the upper diaphragm 507 and the fifth silicon substrate 505 because the lower diaphragm 506 and the upper diaphragm 507 are bent by pressure. Changes, and the pressure is detected based on this change. The capacitance of the region disposed in the frame shape of the peripheral portion where the third silicon substrate 501, the second insulating layer 503, the fifth silicon substrate 505, the third insulating layer 504, and the fourth silicon substrate 502 overlap is as follows. Since it does not change with pressure, it acts as a parasitic capacitance.

  In the configuration shown in Patent Document 1, when the thickness of the second insulating layer 503 or the third insulating layer 504 is increased in order to reduce the parasitic capacitance, the capacitance is inversely proportional to the distance between the electrodes. The change in capacitance between the lower diaphragm 506 and the upper diaphragm 507 and the fifth silicon substrate 505 becomes smaller with respect to the change in pressure, and the sensitivity is lowered.

  In the configuration shown in Patent Document 1, in order to reduce the parasitic capacitance, the width of the region disposed in the frame shape of the peripheral portion where the second insulating layer 503, the fifth silicon substrate 505, and the third insulating layer 504 overlap is set. If it is narrowed, the mechanical strength of the second insulating layer 503 formed by coating becomes weak, and it may be impossible to obtain excellent sealing properties.

  When the width is narrowed, the alignment margin between the patterns of the insulating layers 503 and 504 and the fifth silicon substrate 505 and the exposure mask is reduced. Therefore, when the third silicon substrate 501 and the fourth silicon substrate 502 are wet-etched using the patterned resist layer as a mask, the third silicon substrate 501 and the fourth silicon substrate 502, the insulating layers 503, 504, and the fifth In some cases, the silicon substrate 505 did not properly overlap. As a result, good sealing properties may not be obtained.

  An object of the present invention is to solve the above-described conventional problems, and provide a capacitance type physical quantity sensor capable of reducing parasitic capacitance and obtaining good sealing performance and good sensitivity, and a method for manufacturing the same. It is to be.

  The capacitance type physical quantity sensor of the present invention includes a sensor substrate that detects a physical quantity, a base substrate that is bonded to the sensor substrate, and an insulating layer that bonds the sensor substrate and the base substrate. The sensor substrate has a movable part that can be displaced, and a peripheral part that is located around the movable part and is joined to the base substrate via the insulating layer. The physical quantity can be detected based on a change in capacitance between the insulating layer, the insulating layer has a protruding portion protruding in a direction away from the base substrate, and the entire protruding portion is covered with the peripheral portion. It is characterized by.

  Since the entire convex portion is covered with the peripheral portion, the sensor substrate is provided in a region corresponding to the convex portion on the surface where the peripheral portion and the base substrate face each other with the insulating layer interposed therebetween. The distance between the substrate and the base substrate is increased. Since the parasitic capacitance is inversely proportional to the distance, the parasitic capacitance can be reduced.

  The insulating layer has the convex portion protruding in a direction away from the base substrate, and an insulating layer thinner than the convex portion is continuously provided inside the convex portion. Therefore, the distance between the movable part and the base substrate can be narrowly provided despite the provision of the convex part. Since the electrostatic capacity is inversely proportional to the distance between the electrodes, by providing the distance narrowly, the output change based on the change of the electrostatic capacity when the movable part is displaced increases, so that the sensitivity can be increased.

  When the width of the insulating layer between the peripheral portion of the sensor substrate and the base substrate is widened at the convex portion, the convex portion protrudes in a direction away from the base substrate. The increase in parasitic capacitance can be kept low. In addition, by increasing the width of the insulating layer, it is possible to ensure a good sealing property between the sensor substrate and the base substrate.

  As described above, according to the present invention, it is possible to reduce the parasitic capacitance and obtain good sealing performance and good sensitivity.

  It is preferable that the convex portion is provided along the outer periphery of the sensor substrate. According to such an aspect, the distance between the sensor substrate and the base substrate can be increased in a wide area of a region where the peripheral portion of the sensor substrate and the base substrate face each other with the insulating layer interposed therebetween. . Therefore, it is possible to effectively reduce the parasitic capacitance generated between the peripheral portion of the sensor substrate and the base substrate.

  It is preferable that the convex portion has a concave portion or a cavity that is recessed in a direction away from the base substrate. If it is such an aspect, the dielectric constant of the said recessed part and the said cavity which do not have the said insulating layer is smaller than the dielectric constant of the said insulating layer. Since the parasitic capacitance is proportional to the dielectric constant, the parasitic capacitance generated between the peripheral portion of the sensor substrate and the base substrate can be further reduced.

  The sensor substrate is formed inside the outer peripheral side surface of the base substrate, and the insulating layer is a surface of the base substrate between the peripheral portion and the base substrate, and at least around the sensor substrate It is preferable that it is formed so as to protrude. According to such an aspect, in addition to the parasitic capacitance being reduced because the insulating layer has the convex portion, the sealing performance between the sensor substrate and the base substrate is effectively improved. Can do.

  The sensor substrate is formed inside the outer peripheral side surface of the base substrate, and the insulating layer is formed between the outer peripheral side surface of the base substrate and the periphery of the sensor substrate from between the peripheral edge portion and the base substrate. It is preferable that it is formed over the entire extended surface of the base substrate located between them.

  If it is such an aspect, in addition to the parasitic capacitance being reduced because the insulating layer has the convex portion, the mechanical strength is further increased because the insulating layer has a large area, It is possible to further effectively improve the sealing performance between the sensor substrate and the base substrate.

  It is preferable that a maximum distance separating the base substrate and the inner surface of the concave portion in a direction orthogonal to the base substrate is larger than a thickness of the insulating layer not located on the convex portion. In such an aspect, the distance between the peripheral portion of the sensor substrate and the base substrate can be increased to the maximum distance from the thickness of the insulating layer at the position of the convex portion. Parasitic capacitance generated between the peripheral portion of the sensor substrate and the base substrate can be reduced.

  It is preferable that the movable portion has a thin portion that is recessed in a direction away from the base electrode rather than the peripheral portion on a surface facing the base electrode. With such an aspect, the movable range of the movable part that is displaced by the physical quantity is expanded, so that the measurement range of the detected physical quantity can be expanded. As a result, it is possible to reduce the parasitic capacitance in a wide measurement range.

  It is preferable that the movable portion has a thick portion on the surface facing the base substrate that is located inside the thin portion in a direction parallel to the surface and protrudes in a direction approaching the base substrate. . Sensitivity can be improved more effectively because the thin-walled portion is thin and is easily sensitive to physical quantities, and the distance between the movable portion and the base substrate is reduced. Therefore, in addition to the parasitic capacitance being reduced because the insulating layer has the convex portions, the sensitivity can be effectively improved.

  A second thin-walled portion that is located on the inner surface of the thick-walled portion in a direction parallel to the surface on the surface facing the base substrate and is recessed in a direction away from the base electrode than the thick-walled portion. It is preferable to have.

  When the movable part bends due to a physical quantity, the central part of the movable part bends to the maximum. Therefore, providing the second thin portion at the center of the movable part can increase the displacement of the movable part due to the physical quantity, and thus can further increase the measurement range of the physical quantity to be detected.

  It is preferable that the insulating layer is formed so as not to protrude from the outer peripheral side surface of the sensor substrate. According to such an aspect, the area of the insulating film between the peripheral portion of the sensor substrate and the base substrate can be reduced, so that the parasitic capacitance can be more effectively reduced.

  Preferably, the sensor substrate and the base substrate include a silicon substrate, and the insulating layer is obtained by thermally oxidizing the silicon substrate constituting the sensor substrate. In such an embodiment, the sensor substrate and the base substrate are bonded to each other by the insulating film having high mechanical strength obtained by thermal oxidation. Therefore, the bonding force between the sensor substrate and the base substrate can be effectively improved, and a good sealing property can be obtained.

  A first terminal portion and a second terminal portion are provided on the surface of the base substrate together with the sensor substrate, and the first terminal portion is integrally pulled out from the peripheral portion of the sensor substrate by the silicon substrate. The second terminal portion is separated from the sensor substrate and formed from the silicon substrate formed through the base substrate and the insulating layer. And an electrode pad that is provided in a contact hole that penetrates the separation layer and the insulating layer and communicates with the surface of the base substrate, and is electrically connected to the base substrate. According to such an aspect, it is possible to provide the first terminal portion and the second terminal portion with a simple structure.

The manufacturing method of the present invention includes a sensor substrate that detects a physical quantity, a base substrate that is bonded to the sensor substrate, and an insulating layer that bonds the sensor substrate and the base substrate. , A movable part that can be displaced, and a peripheral part that is located around the movable part and is joined to the base substrate via the insulating layer, and between the movable part and the base substrate. Capacitance type physical quantity in which the physical quantity can be detected based on a change in capacitance, the insulating layer has a convex portion protruding in a direction away from the base substrate, and the entire convex portion is covered by the peripheral edge portion. A method for manufacturing a sensor, comprising:
Forming a first silicon substrate having the movable portion, a bonding region extending around the movable portion, and the insulating layer having a convex portion protruding in a direction away from the base substrate at the peripheral portion;
A second silicon substrate serving as the base substrate is prepared, and the first silicon substrate and the second silicon substrate are separated from each other with a gap between the movable portion and the base substrate and the movable portion and the base substrate facing each other. A step (b) of bonding a silicon substrate via the insulating layer;
A step (c) of removing an unnecessary portion of the bonding region in a state where the sensor substrate is left inside the outer peripheral side surface of the base substrate so that the peripheral portion covers the entire convex portion; ,
It is characterized by including.

  In the manufacturing method of the present invention, after the first silicon substrate having the movable part and the second silicon substrate are bonded via the insulating layer, the unnecessary portion of the first silicon substrate is removed. The peripheral edge portion is formed so as to cover the entire convex portion.

  According to such an aspect, in the region corresponding to the convex portion of the surface where the peripheral edge portion of the sensor substrate and the base substrate face each other with the insulating layer interposed therebetween, the gap between the sensor substrate and the base substrate. The distance becomes larger. Since the parasitic capacitance is inversely proportional to the distance, the parasitic capacitance can be reduced.

  The insulating layer has the convex portion protruding in a direction away from the base substrate, and an insulating layer thinner than the convex portion is continuously provided inside the convex portion. Therefore, the distance between the movable part and the base substrate can be narrowly provided despite the provision of the convex part. Since the electrostatic capacity is inversely proportional to the distance between the electrodes, the distance can be set narrow so that a change in output based on a change in the electrostatic capacity when the movable part is displaced increases, so that the sensitivity can be increased.

  If it is such an aspect, the said sensor board | substrate and the said sensor board | substrate are joined via the said insulating layer with high mechanical strength. Therefore, good sealing properties can be obtained between the sensor substrate and the base substrate.

  As described above, according to the manufacturing method of the present invention, it is possible to reduce the parasitic capacitance and obtain good sealing performance and good sensitivity.

  In the step (c), the insulating layer is preferably left on the surface of the base substrate so as to protrude from the outer periphery of the sensor substrate. By leaving the insulating layer so as to protrude from the outer periphery of the sensor substrate, a good sealing property between the sensor substrate and the base substrate is stably maintained.

  In the step (c), it is preferable that the insulating layer is left over the entire extended surface of the base substrate located between the outer peripheral side surface of the base substrate and the periphery of the sensor substrate. By leaving the insulating layer over the entire extended surface of the base substrate, the mechanical strength of the insulating layer is further increased. The base substrate and the insulating layer have a wide bonding area. Therefore, it is possible to improve the sealing performance between the sensor substrate and the base substrate more effectively.

  In the step (a), after forming a concave portion in the portion that becomes the peripheral portion of the first silicon substrate, the first silicon substrate is thermally oxidized to have the convex portion in the portion that becomes the peripheral portion. It is preferable to form the insulating layer. With such an aspect, the insulating layer having the convex portion at the portion that becomes the peripheral portion is in a sufficiently high bonding force (bonding force) with the first silicon substrate in a simple process. Mechanically high strength can be formed.

  In the step (b), the first silicon substrate and the second silicon substrate are preferably bonded by silicon fusion bonding. With such an aspect, the first silicon substrate and the second silicon substrate can be bonded with a sufficient bonding force (bonding force).

  In the step (a), it is preferable that a thin-walled portion that is recessed in a direction away from the surface by removing the surface of the first silicon substrate is formed in the movable portion. With such an aspect, the movable range of the movable part that is displaced by the physical quantity is expanded, so that the measurement range of the detected physical quantity can be expanded. As a result, it is possible to reduce the parasitic capacitance in a wide measurement range.

  In the step (a), it is preferable to leave a thick portion that is located inside the thin portion in a direction parallel to the surface of the first silicon substrate and protrudes from the surface of the thin portion. If it is such an aspect, it is easy to be sensitive to a physical quantity because the thin part is thin, and the distance between the movable part and the base substrate is narrowed, thereby improving the sensitivity more effectively. Can do. Therefore, in addition to the parasitic capacitance being reduced because the insulating layer has the convex portions, the sensitivity can be effectively improved.

  In the step (a), a second portion that is located inside the thick portion in a direction parallel to the surface of the first silicon substrate and is recessed in a direction away from the surface by removing the surface of the thick portion. It is preferable to form a thin portion.

  When the movable part bends due to a physical quantity, the central part of the movable part bends to the maximum. Therefore, providing the second thin portion at the center of the movable portion can increase the displacement of the movable portion due to a physical quantity. Therefore, the measurement range of the physical quantity to be detected can be expanded.

  When removing unnecessary portions of the first silicon substrate, the sensor substrate, a lead-out wiring layer drawn integrally from the peripheral portion of the sensor substrate on the surface of the base substrate, and the sensor substrate are separated. The step of bonding the first silicon substrate and the second silicon substrate through the insulating layer before and after the step (c) of removing the unnecessary portion of the first silicon substrate while leaving the separated layer. (B) Thereafter, a step of forming a contact hole at the position of the isolation layer and penetrating through the isolation layer and the insulating layer to the surface of the base substrate made of the second silicon substrate; Forming an electrode pad in the surface of the layer and in the contact hole.

  Accordingly, the first terminal portion having the lead-out wiring layer and the electrode pad and the electrode pad provided in the separation layer and the contact hole are provided on the same formation surface side as the sensor substrate in a simple process. A second terminal portion can be formed.

  According to the capacitance type physical quantity sensor of the present invention, it is possible to reduce the parasitic capacitance and obtain good sealing performance and good sensitivity.

It is a perspective view of the capacitance-type physical quantity sensor in 1st Embodiment. It is the cross-sectional schematic cut | disconnected along the AA line of the capacitance-type physical quantity sensor shown in FIG. It is the cross-sectional schematic cut | disconnected along the BB line of the capacitance-type physical quantity sensor shown in FIG. It is a section schematic diagram of the 1st modification in a 1st embodiment. It is a section schematic diagram of the 2nd modification in a 1st embodiment. It is explanatory drawing of the manufacturing method of the electrostatic capacitance type physical quantity sensor in 1st Embodiment. It is explanatory drawing of the manufacturing method of the electrostatic capacitance type physical quantity sensor in 1st Embodiment. It is a perspective view of the 3rd modification in a 1st embodiment. It is a perspective view of the 4th modification in a 1st embodiment. FIG. 10 is a schematic cross-sectional view taken along line CC of the capacitance type physical quantity sensor shown in FIG. 9. It is a section schematic diagram of the 5th modification in a 1st embodiment. It is a section schematic diagram of a capacity type physical quantity sensor in a 2nd embodiment. It is a section schematic diagram of a capacitance type physical quantity sensor in a 3rd embodiment. It is a section schematic diagram of a capacity type physical quantity sensor in a 4th embodiment. 1 is a schematic cross-sectional view of a semiconductor pressure sensor disclosed in Patent Document 1.

  FIG. 1 is a perspective view of a capacitance type physical quantity sensor according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the capacitance type physical quantity sensor of the present embodiment cut along line AA in FIG. is there. FIG. 3 is a schematic cross-sectional view of the capacitance type physical quantity sensor of the present embodiment cut along the line BB in FIG. 2 and 3 are shown in FIG. 1 with the dimensional ratio changed.

  Regarding the capacitance type physical quantity sensor shown in each figure, the Y direction is the left-right direction, the Y1 direction is the left direction, the Y2 direction is the right direction, the X direction is the front-back direction, the X1 direction is the front direction, and the X2 direction is It is the backward direction. Further, the direction orthogonal to both the X direction and the Y direction is the vertical direction (Z direction; height direction), the Z1 direction is the upward direction, and the Z2 direction is the downward direction. Each drawing is illustrated with dimensions appropriately changed for easy viewing.

<First Embodiment>
The capacitive physical quantity sensor 1 shown in FIGS. 1, 2, and 3 includes a sensor substrate 11 formed from a silicon substrate, a base substrate 12 formed from a silicon substrate, a sensor substrate 11 and a base substrate 12. And an insulating layer 13 for joining the two.

  As shown in FIGS. 1, 2, and 3, the sensor substrate 11 has a movable portion 14 that can be displaced in the height direction with a distance 17 in the height direction (Z) from the base substrate 12. 1 and a peripheral portion 15 located around the movable portion 14 and joined to the base substrate 12 via the insulating layer 13 (the movable portion 14 and the peripheral portion 15 shown in FIG. The dotted line between them indicates the boundary between them and is shown for convenience).

  The capacitance type physical quantity sensor 1 of the present embodiment is a capacitance type pressure sensor. That is, as shown in FIGS. 2 and 3, when pressure acts on the movable part 14 from the upper direction (Z1), the movable part 14 is displaced in the height direction (Z). As a result, the capacitance between the movable portion 14 and the base substrate 12 changes, and the pressure is detected based on the change in capacitance.

  However, the capacitance of the region where the peripheral portion 15 of the sensor substrate 11 and the base substrate 12 are joined via the insulating layer 13 does not change due to the pressure from the upper direction (Z1), and thus acts as a parasitic capacitance.

  In the present embodiment, the capacitance type physical quantity sensor 1 is a capacitance type pressure sensor, but is not limited thereto. Capacitance type acceleration sensors, impact sensors, vibration type gyros, variable capacitors and the like are also possible.

  As shown in FIGS. 2 and 3, the insulating layer 13 is formed to have a convex portion 16 that protrudes in a direction away from the base substrate 12 (Z1 direction). And the convex part 16 is formed so that it may overlap with the peripheral part 15 of the sensor board | substrate 11, and the whole convex part 16 is covered by the peripheral part 15. FIG.

  As shown in FIG. 3, the convex portion 16 includes a top portion 16 a that is the portion farthest from the base substrate 12, and an inner peripheral side portion 16 b that is connected to the periphery of the inner peripheral side of the top portion 16 a and extends to the base substrate 12. The outer peripheral side portion 16c connected to the periphery of the outer peripheral side of the top portion 16a and extending to the base substrate 12, and the thin insulating layer 16d connected to the end of the inner peripheral side portion 16b on the base substrate 12 side. And the whole convex part 16 is comprised from the top part 16a, the inner peripheral side part 16b, the outer peripheral side part 16c, and the thin insulating layer 16d. However, the width dimension in the normal direction of the inner periphery of the convex portion 16 of the thin insulating layer 16d is about 10% to 50% of the width dimension in the normal direction of the inner periphery of the convex portion 16 of the top portion 16a.

  Therefore, the distance between the sensor substrate 11 and the base substrate 12 in the portion where the peripheral edge portion 15 and the convex portion 16 overlap in the surface where the peripheral edge portion 15 of the sensor substrate 11 and the base substrate 12 face each other with the insulating layer 13 therebetween. Becomes larger. Since the parasitic capacitance is inversely proportional to the distance between the electrodes, according to the present embodiment, the parasitic capacitance can be reduced.

  In the present embodiment, the convex portion 16 is continuously provided in a ring shape along the entire outer periphery of the sensor substrate 11, but is not limited thereto. The convex portion 16 may be partially provided along the outer periphery of the sensor substrate 11.

  In the present embodiment, as shown in FIGS. 2 and 3, the insulating layer 13 is formed with a convex portion 16 protruding in a direction away from the base substrate 12. A thin insulating layer 16 d thinner than the convex portion 16 is provided on the inner peripheral side of the convex portion 16. Therefore, despite having the convex portion 16 protruding in the direction away from the base substrate 12, the distance 17 between the movable portion 14 and the base substrate 12 can be narrowed.

  The capacitance is inversely proportional to the distance between the electrodes, and the interval 17 is provided narrowly by the above-described structure. Therefore, the output change based on the change in the capacitance when the movable portion 14 is displaced in the height direction can be increased, and the sensitivity can be increased. It becomes possible to raise.

  Therefore, according to the present embodiment, it is possible to reduce the parasitic capacitance and improve the sensitivity for detecting the pressure.

  As shown in FIG. 1, the movable portion 14 has a substantially circular planar shape and is located substantially at the center of the base substrate 12, but the sensor substrate 11 having the movable portion 14 and the peripheral portion 15 is the base. As long as it is formed inside the outer peripheral side surface 12a of the substrate, the shape, position, and size are not limited.

  The insulating layer 13 shown in FIGS. 2 and 3 is formed with a substantially constant film thickness. As will be described later, since the insulating layer 13 is formed by thermal oxidation, it is easy to form the insulating layer 13 with a constant thickness. The thickness of the insulating layer 13 is about 0.5 to 2.0 μm.

  As described above, since the sensor substrate 11 is formed inside the outer peripheral side surface 12 a of the base substrate, the extended surface 21 of the base substrate 12 extends around the sensor substrate 11.

  As shown in FIGS. 2 and 3, the insulating layer 13 is not formed between the movable portion 14 and the base substrate 12. The insulating layer 13 is interposed between the peripheral portion 15 of the sensor substrate 11 and the base substrate 12 and joins the sensor substrate 11 and the base substrate 12.

  Further, as shown in FIGS. 1, 2, and 3, the insulating layer 13 of the present embodiment is formed over the entire extended surface 21 of the base substrate 12.

  In the present embodiment, even if the width in the normal direction (T1 in FIG. 2) of the inner periphery of the convex portion 16 of the insulating layer 13 interposed between the peripheral edge portion 15 of the sensor substrate 11 and the base substrate 12 is reduced, the insulation is achieved. Since the layer 13 is formed over the entire extended surface 21 of the base substrate 12, the insulating layer 13 having high mechanical strength can be interposed between the peripheral edge 15 of the sensor substrate 11 and the base substrate 12.

  In this embodiment, as will be described later in the manufacturing method, the insulating layer 13 formed over the entire extended surface 21 of the base substrate 12 has an unnecessary portion of the silicon substrate around the sensor substrate 11. The unnecessary portion is removed from the state of being bonded to the base substrate 12 via 13 and exposed. In such a case, the insulating layer 13 is preferably formed by thermally oxidizing the surface of the silicon substrate that constitutes the sensor substrate 11 that faces the base substrate 12. As will be described later, in the present embodiment, the silicon substrate constituting the sensor substrate 11 is thermally oxidized and bonded between the two silicon substrates by silicon fusion bonding. Since the insulating layer 13 formed on the surface facing the base substrate 12 of the peripheral portion 15 of the sensor substrate 11 is obtained by thermally oxidizing the facing surface, the bonding force (bonding force) between the insulating layer 13 and the peripheral portion 15. The width of the insulating layer 13 (T1 in FIG. 2) interposed between the peripheral edge portion 15 and the base substrate 12 can be reduced. On the other hand, since the bonding area is large between the insulating layer 13 and the base substrate 12 bonded by silicon fusion bonding, a sufficient bonding force can be obtained. Therefore, even if the width (T1) is narrowed, the bonding force between the base substrate 12 and the peripheral portion 15 of the sensor substrate 11 can be secured sufficiently high. Therefore, the base substrate 12 and the sensor substrate 11 are bonded with good sealing properties.

  Therefore, the opposing area formed through the insulating layer 13 between the peripheral portion 15 of the sensor substrate 11 and the base substrate 12 can be narrowed, and the parasitic capacitance can be reduced. As described above, the parasitic capacitance can be reduced, and the base substrate 12 and the sensor substrate 11 are bonded with good sealing properties.

  In Patent Document 1, as shown in FIG. 15, a cross section in which the third insulating layer 504 is extended to the surface of the fifth silicon substrate 505 extending outward from the fourth silicon substrate 502 in order to form the electrode pad 508. Although the figure is shown, a configuration in which the fourth silicon substrate 502 is formed inside the outer peripheral side surface of the fifth silicon substrate 505 and the insulating layer is protruded to the entire periphery of the fourth silicon substrate 502 is disclosed. Not. Further, Patent Document 1 does not describe anything about improving the sealing performance by extending the third insulating layer 504 to the surface of the fifth silicon substrate 505 that extends outward from the fourth silicon substrate 502. .

  As shown in FIG. 1, a first terminal portion 22 and a second terminal portion 23 are provided on the extended surface 21 on the same formation surface side as the sensor substrate 11. The first terminal portion 22 is a lead wiring layer 24 that is integrally drawn from the peripheral edge portion 15 of the sensor substrate 11 by a silicon substrate, and a first electrode pad 25 that is formed on the front end portion 24 a of the lead wiring layer 24. And is configured. As shown in FIGS. 1 and 3, the second terminal portion 23 is separated from the sensor substrate 11 and formed on the surface of the insulating layer 13, and the second terminal portion 23 penetrates through the separating layer 26 and the insulating layer 13. The second electrode pad 28 is provided in a contact hole 27 that communicates with the surface of the substrate 12 and is electrically connected to the base substrate 12. The electrode pads 25 and 28 are formed by vapor deposition, sputtering, plating, or the like of a metal layer such as aluminum or gold.

  Although it is possible to pull out each terminal part 22 and 23 from the back surface side of the base substrate 12, in that case, since an insulating layer is newly needed on the back surface of the base substrate 12, the extended surface 21 of the base substrate 12 is used. The terminal portions 22 and 23 can be formed with a simple structure by forming the terminal portions 22 and 23 using the insulating layer 13 formed so as to spread over the entire area.

  The present embodiment is characterized in that the insulating layer 13 is formed over the entire extended surface 21 of the base substrate 12, and here, “all the area” means all regions of the extended surface 21, that is, in plan view. Although it is desirable that the base substrate 12 is invisible, the insulating layer 13 protrudes outward from the entire outer periphery of the sensor substrate 11, and at this time, the insulating layer 13 is slightly around the corner of the extended surface 21, for example. In the case where there is a missing portion, or as in the third modification in the first embodiment shown in FIG. 8, the insulating layer 13 is not formed along the outer periphery of the base substrate 12, and the outer periphery of the insulating layer 13 Is defined as “entire area” even if it is smaller than the outer circumference of the base substrate 12. In addition, if 90% or more of the extended surface 21 is covered with the insulating layer 13, it is determined as the entire region. If the insulating layer 13 is deleted after being along the outer periphery of the base substrate 12, the number of processes increases, but chipping of the insulating layer 13 can be prevented when dicing later. If there is no such problem, it is preferable that the insulating layer 13 is provided on the entire surface of the extended surface 21 of the base substrate 12 because the process is reduced accordingly.

  As shown in FIG. 2, the maximum distance (T2) separating the inner surfaces of the base substrate 12 and the recess 32 in the direction orthogonal to the base substrate 12 (Z direction) is the thickness (T3) of the insulating layer 13 that is not located on the protrusion 16. Larger).

  In such an embodiment, the distance between the peripheral edge 15 of the sensor substrate 11 and the base substrate 12 at the position of the convex portion 16 is set to a maximum distance (T2) from the thickness (T3) of the insulating layer 13. Can be bigger. Therefore, the parasitic capacitance generated between the peripheral portion 15 of the sensor substrate 11 and the base substrate 12 can be reduced.

  The reason why the sensor substrate 11 and the base substrate 12 need to have good sealing properties is as follows. When the sealing property between the sensor substrate 11 and the base substrate 12 is poor, for example, the gas to be measured enters the gap where the movable portion 14 and the base substrate 12 face each other. For this reason, when the gas or the like is wet, condensation may occur in the gap, which may hinder the movement of the movable portion 14, and the dielectric constant between the movable portion 14 and the base substrate 12 changes. So undesirable. In addition, dust or mist mixed in the gas to be measured may enter the gap and hinder the movement of the movable portion 14.

  The reason for reducing the parasitic capacitance is as follows. Since the parasitic capacitance is a component of capacitance that is not sensitive to changes in pressure, it acts as an output offset component, for example. Therefore, the offset component can be reduced by reducing the parasitic capacitance.

  Further, for example, it is possible to configure a resonance circuit using the electrostatic capacitance between the movable portion 14 and the base substrate 12, and to measure the change in pressure from the change in resonance frequency. That is, the capacitance is changed by the displacement of the movable portion 14 in accordance with the change in pressure, and as a result, the resonance frequency is changed. Therefore, the pressure can be measured from the change in the resonance frequency.

  Also in this case, the parasitic capacitance acts as an offset component. The pressure cannot be measured with high accuracy. Therefore, it is necessary to reduce the parasitic capacitance in order to keep the offset component small.

  As shown in FIGS. 2 and 3, in the present embodiment, the convex portion 16 is formed with a concave portion 32 that is recessed. In the first modification of the first embodiment shown in FIG. 4, a cavity 16 e is formed inside the convex portion 16. In such a structure, since the insulating layer 13 is formed by thermal oxidation as will be described later, the opening of the recess 32 is blocked by the insulating layer depending on the width and shape of the recess 32 and the amount of oxidation of the silicon substrate. It is formed by peeling off.

  As shown in FIG. 4, the first modified example has a convex portion 16 and further has a cavity 16 e having a dielectric constant smaller than that of the insulating layer 16 inside the convex portion 16, so that parasitic capacitance can be reduced. . However, the concave portion 32 shown in FIGS. 2 and 3 is larger than the cavity 16e shown in FIG. Therefore, the parasitic capacitance can be further reduced in the first embodiment than in the first modification.

  FIG. 5 shows a schematic cross-sectional view of a second modification of the first embodiment. In the second modification, the concave portion 32 of the first embodiment is filled with an insulating layer, and the inside of the convex portion 16 is filled with an insulating layer. Such a structure may be formed depending on the width and shape of the recess 32 and the amount of oxidation of the silicon substrate.

  In the second modification, as shown in FIG. 5, the parasitic capacitance can be reduced by having the convex portion 16. However, for the same reason as the first modification, the first embodiment is preferable to the second modification.

  FIG. 9 shows a perspective view of a fourth modification of the first embodiment. In the fourth modification example, as shown in FIG. 9, the insulating layer 13 extends from between the peripheral portion 15 of the sensor substrate and the base substrate 12 to the extended surface 21 that is the surface of the base substrate 12, and around the sensor substrate 11. Although it is formed so as to protrude, it does not cover the entire extended surface 21 of the base substrate 12. In FIG. 9, the insulating layer 13 protrudes around the terminal portions 22 and 23.

  FIG. 10 is a schematic cross-sectional view taken along the line CC shown in FIG. In the fourth modified example, as shown in FIG. 10, the insulating layer 13 is formed on the surface of the base substrate 12 between the peripheral edge portion 15 and the base substrate 12, and at least protrudes around the sensor substrate 11. Has been.

  As shown in FIG. 10, the peripheral portion 15 of the sensor substrate 11 covers the entire convex portion 16. For this reason, even if the planar dimensions of the sensor substrate 11 vary slightly, or even if there is a slight misalignment in the exposure process, the convex portion 16 is kept covered with the peripheral edge portion 15. Therefore, the parasitic capacitance is stably reduced. In addition, since the sensor substrate 11 and the base substrate 12 are bonded by the mechanically strong insulating layer 13, the sealing performance can be effectively improved.

  In FIG. 11, the cross-sectional schematic of the 5th modification in 1st Embodiment is shown. In this modification, the insulating layer 13 is formed so as not to protrude from the outer peripheral side surface 11a of the sensor substrate. The cross-sectional schematic diagram shown in FIG. 11 illustrates a portion where the insulating layer 13 is slightly recessed inside the outer peripheral side surface 11a of the sensor substrate.

  As described above, in the fifth modification, the peripheral portion 15 of the sensor substrate 11 and the base substrate 16 face each other through the insulating film 13 in a narrower area, that is, a dielectric constant that is partially free of the insulating layer 13. Therefore, the parasitic capacitance can be reduced more effectively.

  A manufacturing method of the capacitance type physical quantity sensor 1 of the present embodiment shown in FIGS. 1, 2, and 3 will be described with reference to FIGS.

  In the step shown in FIG. 6A, a resist layer 31 is patterned on the surface 30a of the first silicon substrate 30, and the surface 30a not covered with the resist layer 31 is fixed by ion etching means such as reactive ion etching. Sharpen only the thickness. Thereby, the concave portion 32 is formed in a ring shape on the surface 30a. The first silicon substrate 30 is a substrate to be a sensor substrate 11 later, and the surface 30a is a surface facing the base substrate.

In the step shown in FIG. 6B, after removing the resist layer 31 in FIG. 6A, the surface of the first silicon substrate 30 is thermally oxidized at a temperature of 900 to 1200.degree. As a result, insulating layers (SiO ₂ ) 33 and 34 are formed on the front surface 30a and the back surface 30c of the first silicon substrate 30 by thermal oxidation. The insulating layer 33 formed on the surface 30a of the first silicon substrate 30 is formed with a substantially constant thickness following the unevenness of the surface 30a. Thus, the convex part 16 which arrange | positions the peripheral part of a sensor board | substrate in the direction away from a base substrate later is formed in the part of the recessed part 32. FIG.

  6C, a resist layer 35 is formed on the insulating layer 33 formed on the surface 30a of the first silicon substrate 30, and the insulating layer 33 not covered with the resist layer 35 is ion-etched. Remove the existing method. In this way, the insulating layer 33 in the portion that will later become the movable portion 14 is removed.

  The portion where the insulating layer 33 is left is a bonding region to be bonded to the second silicon substrate 40 (base substrate) in the next process.

  In addition, after FIG.6 (d), the remaining insulating layer 33 is demonstrated as the insulating layer 13 used by FIG. 2, FIG. In the step of FIG. 6D, after removing the resist layer 35 of FIG. 6C, the first silicon substrate 30 of FIG. 6C is turned over, and the insulating layer 13 of the first silicon substrate 30 is formed. The other side is brought into contact with a second silicon substrate 40 which will later become a base substrate. The silicon substrates 30 and 40 are bonded to each other by silicon fusion bonding. Silicon fusion bonding is a kind of silicon direct bonding. For example, a first silicon substrate 30 provided with an insulating layer 13 by thermal oxidation and a second silicon substrate 40 are bonded together by hydrogen bonding, and then heat-treated to form Si—O. This is a technique of bonding by Si. The heat treatment temperature is about 700 to 1100 ° C., and the heat treatment time is 1 hour or longer.

  Next, in the step of FIG. 6E, both the first silicon substrate 30 and the second silicon substrate 40 are cut to a predetermined thickness by cutting or the like. The silicon substrate in which the dotted line part is cut is shown. Thereby, the base substrate 12 having a predetermined thickness is completed. Hereinafter, the second silicon substrate 40 will be described as the base substrate 12.

  In the step shown in FIG. 7A, a resist layer 41 is formed on the surface of the first silicon substrate 30, and the first silicon substrate 30 and the insulating layer 13 that are not covered with the resist layer 41 are subjected to reactive ion etching or the like. A contact hole 27 that leads to the surface of the base substrate 12 is formed by etching using an ion etching technique.

  Here, the formation position of the contact hole 27 is a portion to be the separation layer 26 shown in FIGS. 1 and 3 later.

  When the resist layer 41 is removed and a new resist layer (not shown) is provided in the step shown in FIG. 7B, or a metal layer such as aluminum is formed in the contact hole 27 using the resist layer 41 as it is. The second electrode pad 28 is formed by an existing method such as sputtering, vapor deposition, or plating. At this time, the first electrode pad 25 shown in FIG. 1 is also formed on the surface to be the tip 24 a of the lead-out wiring layer 24.

  Next, in a process shown in FIG. 7C, a resist layer 42 is formed on the surface of the first silicon substrate 30, and the first silicon substrate 30 not covered with the resist layer 42 is subjected to ion etching technology such as reactive ion etching. To remove. The planar pattern of the resist layer 42 is a planar shape of the sensor substrate 11, the lead-out wiring layer 24, and the separation layer 26 shown in FIG. When the first silicon substrate 30 is etched, it is necessary to perform a selective etching process so that the insulating layer 13 is not removed.

  7C, the first silicon substrate 30 is cut so that the sensor substrate 11 is formed inside the outer peripheral side surface 12a of the base substrate. In this way, the insulating layer 13 is left over the entire extended surface 21 of the base substrate 12 extending around the sensor substrate 11.

  The sensor substrate 11 has a movable portion 14 that can be displaced in the height direction and a peripheral edge portion 15 around the movable portion 14, and the peripheral edge portion 15 and the base substrate 12 are joined by an insulating layer 13. A convex portion 16 is provided so as to overlap the peripheral portion 15, and the peripheral portion 15 covers the entire convex portion 16.

  In the step of FIG. 7C, the parasitic capacitance can be reduced by reducing the width in the normal direction of the inner periphery of the convex portion 16 (T1 in FIG. 7C) where the peripheral edge portion 15 and the insulating layer 13 overlap. . Further, since the distance between the sensor substrate 11 and the base substrate 12 increases at the portion where the peripheral edge portion 15 and the convex portion 16 overlap, the parasitic capacitance is reduced. On the other hand, since the insulating layer 13 is left over the entire extended surface 21 of the base substrate 12, the mechanical strength of the insulating layer 13 can be sufficiently maintained, and the gap between the sensor substrate 11 and the base substrate 12 can be maintained. Can be effectively improved.

  Further, as shown in the step of FIG. 6B, in this embodiment, the surface of the first silicon substrate 30 that forms the sensor substrate is thermally oxidized to form the insulating layer 33, and in the step of FIG. After removing the insulating layer 33 in the portion 14, the first silicon substrate 30 and the second silicon substrate 40 are joined by silicon fusion bonding in the step of FIG. 6D. 7C, when unnecessary portions of the first silicon substrate 30 are removed, the peripheral portion 15 and the insulating layer 13 are insulated from the peripheral portion 15 even if the width (T1) where the peripheral portion 15 and the insulating layer 13 overlap is narrowed. The bonding force (bonding force) with the layer 13 is sufficiently high. On the other hand, since the base substrate 12 and the insulating layer 13 have a wide bonding area, the sensor substrate 11 and the base substrate 12 with the insulating layer 13 interposed therebetween. It is possible to effectively increase the bonding force between the two and improve the sealing performance.

  Further, in the present embodiment, the bonding of both the silicon substrates 30 and 40 in the step of FIG. 6D is different from the structure shown in Patent Document 1, for example, and the alignment accuracy of both the silicon substrates 30 and 40 is unnecessary. The manufacturing process can be facilitated. Therefore, in this embodiment, no special capital investment or the like is required, and an increase in manufacturing cost can be suppressed.

<Second Embodiment>
In the present embodiment, as shown in FIG. 12, the movable portion 14 includes a thin portion 18 that is recessed in a direction (Z1 direction) in which the entire facing surface 14 a facing the base substrate 12 is separated from the base substrate 12. Yes.

  Therefore, according to the present embodiment, the entire surface 14 a facing the base substrate 12 is the thin portion 18, thereby providing a large gap 17 between the movable portion 14 and the base substrate 12. Therefore, since the maximum displacement amount of the movable part 14 can be increased as compared with the first embodiment, the measurement range of the detected pressure can be widened, that is, the dynamic range of the detected pressure (Dynamic range). Can be wide.

  Further, as shown in FIG. 12, the convex portion 16 is formed so as to overlap the peripheral edge portion 15 of the sensor substrate 11, and the entire convex portion 16 is covered with the peripheral edge portion 15. Therefore, the distance between the sensor substrate 11 and the base substrate 12 is increased in a portion where the peripheral edge portion 15 and the convex portion 16 overlap in the surface where the peripheral edge portion 15 and the base substrate 12 face each other with the insulating layer 13 therebetween. Thus, this embodiment has a structure for reducing parasitic capacitance.

  Therefore, in this embodiment, while providing the convex part 16 so that the whole peripheral part 15 may be covered, providing the thin part 18 in the movable part 14 WHEREIN: The subject of this invention of reducing a parasitic capacitance is measured widely. A range is possible.

  In addition, providing the thin portion 18 in the movable portion 14 means that the first silicon substrate 30 that is not covered with the resist layer 35 is removed by ion etching or the like after the insulating layer 33 is removed in the step of FIG. This can be achieved by grinding with existing methods.

<Third Embodiment>
In the present embodiment, as shown in FIG. 13, the movable portion 14 has a thin portion 18 in which the facing surface 14 a facing the base substrate 12 rather than the peripheral portion 15 is recessed in a direction away from the base substrate 12 (Z1 direction). Configured. A thick portion 19 is formed in the center of the movable portion 14 so that the facing surface 14a protrudes in a direction closer to the base substrate 12 (Z2 direction) than the thin portion 18. That is, the movable portion 14 shown in FIG. 13 has a structure in which a thick portion 19 is provided at the approximate center, and a ring-shaped thin portion 18 having a concave opposed surface 14a is formed around it. As shown in FIG. 13, by providing the movable portion 14 with the thin portion 18, the movable portion 14 can be easily displaced in the height direction (Z). Further, by providing the thick portion 19 that protrudes closer to the base substrate 12 than the thin portion 18, the distance 17 between the movable portion 14 and the base substrate 12 becomes narrow at the position of the thick portion 19.

  Therefore, according to the present embodiment, the thin part 18 is easy to be sensitive to pressure because the thin part 18 is thin, and the capacitance 17 is inversely proportional to the distance between the electrodes by narrowing the interval 17. Sensitivity can be improved more effectively because the output changes greatly based on the change in capacitance when displaced in the height direction.

  As described above, in the present embodiment, the entire convex portion 16 is provided so as to be covered with the peripheral edge portion 15, and the thick portion 19 is provided in the central portion of the thin portion 18 provided in a ring shape on the movable portion 14. Thus, in addition to reducing the parasitic capacitance, the sensitivity can be effectively improved.

  In addition, providing the thick part 19 in the center part of the thin part 18 provided in the ring shape in the movable part 14 means that after the insulating layer 33 is removed in the step of FIG. A resist layer covering the region to be formed is formed. Then, the first silicon substrate 30 that is not covered with the resist layer and the resist layer 35 is cut by an existing method such as ion etching, so that the thin portion 18 and the thick portion 19 are formed in the movable portion 14. Can do.

<Fourth Embodiment>
In the present embodiment, as shown in FIG. 14, the movable portion 14 has a thin portion 18 in which the facing surface 14 a facing the base substrate 12 rather than the peripheral portion 15 is recessed in a direction away from the base substrate 12 (Z1 direction). Configured. In addition, a second thin portion 20 that is recessed in a direction away from the base substrate 12 (Z1 direction) is formed at the center of the movable portion 14. A thick portion 19 is formed between the thin portion 18 and the second thin portion 20 so that the facing surface 14a protrudes in a direction closer to the base substrate 12 than the thin portion 18 (Z2 direction). That is, the movable part 14 shown in FIG. 14 has a structure in which a second thin part 20 is formed at the substantially center, a thick part 19 is formed in a ring shape around the periphery, and a thin part 18 is formed in a ring shape around the periphery.

  When the movable part 14 is bent by the pressure, the center of the movable part 14 is bent to the maximum. Therefore, by providing the second thin portion 20 recessed in the direction away from the base substrate 12 (Z1 direction) at the center, the displacement amount of the movable portion 14 due to pressure can be increased. Therefore, the dynamic range of the detected pressure can be widened.

  In addition, the sensitivity can be improved more effectively by providing the thin portion 18 so that it is easy to be sensitive to pressure, or by providing the thick portion 19 and the output greatly changes based on the change in capacitance. It is done.

  Thus, in this embodiment, while providing the convex part 16 so that the whole peripheral part 15 may be covered, the movable part 14 is provided with the thin part 18, the thick part 19, and the 2nd thin part 20 by providing. It is possible to widen the measurement range of the physical quantity to be detected and obtain good sensitivity.

  The second thin-walled portion 20 is provided in the approximate center of the movable portion 14, the thick-walled portion 19 is provided around the second thin-walled portion 20, and the thin-walled portion 18 is provided around the second thin-walled portion. After that, a resist layer covering the thick part 19 is formed. And it can implement | achieve by carving the area | region corresponding to the thin part 18 and the 2nd thin part 20 of the 1st silicon substrate 30 which is not covered with this resist layer and the resist layer 35 by the existing methods, such as ion etching.

DESCRIPTION OF SYMBOLS 1 Capacitance type physical quantity sensor 11 Sensor substrate 11a Outer peripheral side surface 12 of the sensor substrate Base substrate 12a Outer peripheral side surfaces 13, 33, 34 of the base substrate Insulating layer 14 Movable portion 15 Peripheral portion 16 Convex portion 16a Top portion 16b Inner peripheral side portion 16c Outer periphery Side portion 16d Thin insulating layer 16e Cavity 17 Spacing 18 Thin portion 19 Thick portion 20 Second thin portion 21 Extending surface 22 First terminal portion 23 Second terminal portion 24 Lead-out wiring layer 25 First electrode pad 26 Separating layer 27 Contact hole 28 Second electrode pad 30 First silicon substrate 31, 35, 41, 42 Resist layer 32 Recess 40 Second silicon substrate

Claims (21)

A sensor board for detecting physical quantities;
A base substrate bonded to the sensor substrate;
An insulating layer that joins the sensor substrate and the base substrate; and
The sensor substrate has a movable part capable of displacement, and a peripheral part located around the movable part and joined to the base substrate via the insulating layer,
Based on the change in capacitance between the movable part and the base substrate, the physical quantity can be detected,
The capacitive physical quantity sensor characterized in that the insulating layer has a convex portion protruding in a direction away from the base substrate, and the entire convex portion is covered with the peripheral edge portion.   The capacitive physical quantity sensor according to claim 1, wherein the convex portion is provided along an outer periphery of the sensor substrate.   The capacitive physical quantity sensor according to claim 1, wherein the convex portion has a concave portion or a hollow that is recessed in a direction away from the base substrate. The sensor substrate is formed inside the outer peripheral side surface of the base substrate,
The insulating layer is formed so as to protrude from between the peripheral edge portion and the base substrate on the surface of the base substrate and at least around the sensor substrate. Item 4. The capacitance type physical quantity sensor according to any one of items 3 to 4.   The insulating layer is formed from between the peripheral edge portion and the base substrate to the entire extended surface of the base substrate located between the outer peripheral side surface of the base substrate and the periphery of the sensor substrate. The capacitive physical quantity sensor according to claim 4, wherein:   4. The capacitance according to claim 3, wherein a maximum distance separating the base substrate and the inner surface of the concave portion in a direction orthogonal to the base substrate is larger than a thickness of the insulating layer not located on the convex portion. Type physical quantity sensor.   The said movable part has the thin part recessed in the direction which leaves | separates from the said base electrode rather than the said peripheral part in the surface facing the said base substrate, The any one of Claim 1-6 characterized by the above-mentioned. The capacitance type physical quantity sensor according to item.   The movable part has a thick part on a surface facing the base substrate, which is located inside the thin part in a direction parallel to the surface and protrudes in a direction approaching the base substrate. The capacitance-type physical quantity sensor according to claim 7.   A second thin-walled portion that is located on the inner surface of the thick-walled portion in a direction parallel to the surface on the surface facing the base substrate and is recessed in a direction away from the base electrode than the thick-walled portion. The capacitance-type physical quantity sensor according to claim 8, comprising:   The capacitive physical quantity sensor according to claim 1, wherein the insulating layer is formed so as not to protrude from an outer peripheral side surface of the sensor substrate.   11. The sensor substrate and the base substrate include a silicon substrate, and the insulating layer is obtained by thermally oxidizing the silicon substrate constituting the sensor substrate. The capacitance-type physical quantity sensor according to any one of the above.   A first terminal portion and a second terminal portion are provided on the surface of the base substrate together with the sensor substrate, and the first terminal portion is integrally pulled out from the peripheral portion of the sensor substrate by the silicon substrate. The second terminal portion is separated from the sensor substrate and formed from the silicon substrate formed through the base substrate and the insulating layer. And an electrode pad that is provided in a contact hole that penetrates the isolation layer and the insulating layer and communicates with a surface of the base substrate and is electrically connected to the base substrate. 11. The capacitance type physical quantity sensor according to 11. A sensor board for detecting physical quantities;
A base substrate bonded to the sensor substrate;
An insulating layer that joins the sensor substrate and the base substrate; and
The sensor substrate has a movable part capable of displacement, and a peripheral part located around the movable part and joined to the base substrate via the insulating layer,
Based on the change in capacitance between the movable part and the base substrate, the physical quantity can be detected,
The insulating layer has a convex portion protruding in a direction away from the base substrate, and the entire convex portion is covered with the peripheral edge portion.
Forming a first silicon substrate having the movable portion, a bonding region extending around the movable portion, and the insulating layer having a convex portion protruding in a direction away from the base substrate at the peripheral portion;
A second silicon substrate serving as the base substrate is prepared, and the first silicon substrate and the second silicon substrate are separated from each other with a gap between the movable portion and the base substrate and the movable portion and the base substrate facing each other. A step (b) of bonding a silicon substrate via the insulating layer;
A step (c) of removing an unnecessary portion of the bonding region in a state where the sensor substrate is left inside the outer peripheral side surface of the base substrate so that the peripheral portion covers the entire convex portion; ,
The manufacturing method of the capacitance-type physical quantity sensor characterized by the above-mentioned.   14. The method of manufacturing a capacitive physical quantity sensor according to claim 13, wherein, in the step (c), the insulating layer is left on the surface of the base substrate so as to protrude from the outer periphery of the sensor substrate. .   15. In the step (c), the insulating layer is left over the entire extended surface of the base substrate located between the outer peripheral side surface of the base substrate and the periphery of the sensor substrate. A manufacturing method of the capacitance-type physical quantity sensor described.   In the step (a), after forming a concave portion in the portion that becomes the peripheral portion of the first silicon substrate, the first silicon substrate is thermally oxidized to have the convex portion in the portion that becomes the peripheral portion. The method of manufacturing a capacitance type physical quantity sensor according to any one of claims 13 to 15, wherein the insulating layer is formed.   The capacitance type according to any one of claims 13 to 16, wherein in the step (b), the first silicon substrate and the second silicon substrate are bonded by silicon fusion bonding. Manufacturing method of physical quantity sensor.   18. The method according to claim 13, wherein, in the step (a), a thin portion that is recessed in a direction away from the surface by removing the surface of the first silicon substrate is formed in the movable portion. 2. A method for producing a capacitance type physical quantity sensor according to item 1.   19. In the step (a), a thick portion that is located inside the thin portion in a direction parallel to the surface of the first silicon substrate and protrudes from the surface of the thin portion is left. The manufacturing method of the electrostatic capacitance type physical quantity sensor as described in 2.   In the step (a), a second portion that is located inside the thick portion in a direction parallel to the surface of the first silicon substrate and is recessed in a direction away from the surface by removing the surface of the thick portion. The method of manufacturing a capacitance type physical quantity sensor according to claim 19, wherein the thin portion is formed. When removing unnecessary portions of the first silicon substrate, the sensor substrate, a lead-out wiring layer drawn integrally from the peripheral portion of the sensor substrate on the surface of the base substrate, and the sensor substrate are separated. Leaving separated layers,
Before and after the step (c) of removing unnecessary portions of the first silicon substrate, and after the step (b) of bonding the first silicon substrate and the second silicon substrate through the insulating layer, Forming a contact hole at a position of the separation layer, penetrating the separation layer and the insulating layer and reaching the surface of the base substrate made of the second silicon substrate;
Forming an electrode pad in the surface of the lead-out wiring layer and in the contact hole;
21. The method of manufacturing a capacitance-type physical quantity sensor according to claim 13, wherein the capacitance-type physical quantity sensor according to claim 13 is included.