JP2009115499A - Physical quantity sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a physical quantity sensor capable of realizing simultaneously improvement of airtightness and reduction of an electric resistance between an electrode pad and a detection part for detecting displacement of a movable part, concerning a physical quantity sensor, especially, an acceleration sensor formed by using an SOI substrate or the like. <P>SOLUTION: The movable part 6, a support part 10 for supporting the movable part, and the detection part 12 for detecting the displacement of the movable part 6 are formed on an SOI layer 5. A wiring layer 13 formed of a metal is extended from an electric connection position with the detection part to the upside of an insulating layer with a thinner film thickness than the SOI layer, and the electrode pad 14 is connected to the tip part of the wiring layer. A side wall part 17a of a lid body 17 is bonded to a position crossing on an insulating protection layer 16 around the SOI layer 5 and on the wiring layer 13, the electrode pad 14 is exposed to the outside of the side wall part 17a of the lid body 17. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention particularly relates to a physical quantity sensor such as an acceleration sensor formed using an SOI substrate and a method for manufacturing the same.

  Each of the following patent documents discloses an acceleration sensor formed using a MEMS (Micro Electro Mechanical System) technology.

For example, in Patent Document 1, an SOI (Silicon on Insulator) substrate made of a support substrate / insulating layer (described as embedded oxide film 22 in Patent Document 1) / SOI layer is used, and an acceleration sensor is provided on the SOI layer. There is disclosed a structure in which a movable part (described as a movable conductive region R1 in Patent Document 1) and the like are formed and a cap (lid) is covered on the SOI layer.
JP 2007-150098 A JP 2001-196484 A JP 2001-1119040 A

However, the structure of the conventional acceleration sensor has the following problems.
There was no effective means for covering the step of the wiring layer formed of the SOI layer and ensuring hermeticity.

  In the structure of the acceleration sensor of Patent Document 1, the upper surface of the SOI layer is used as a bonding surface with respect to a cap (lid). Further, in order to ensure airtightness, it is necessary to perform bonding on each pad surface simultaneously with the outer periphery of the element, and there are many bonding portions, and it is difficult to ensure airtightness.

  In addition, it is necessary to limit the pad size, position, and interval in order to ensure a sufficient bonding area.

  In addition, in order to obtain sufficient strength and reliability, the pad size and spacing were widened, which resulted in conflict with miniaturization.

  Moreover, in the structure of patent document 1, in order to electrically connect between the movable electrode and fixed electrode for detecting the displacement amount of a movable part via an SOI layer, and an electrode pad (pad electrode P1-P6 in patent document 1). There was a problem that the electrical resistance increased.

  In the configurations described in Patent Document 2 and Patent Document 3, a wiring layer that connects the movable electrode, the fixed electrode, and the pad electrode is embedded in the insulating layer, but the wiring structure is complicated. In addition, it is not a structure capable of improving the airtightness and reducing the electrical resistance.

  Thus, conventionally, in a physical quantity sensor such as an acceleration sensor formed using an SOI substrate, there is no structure that can simultaneously improve airtightness and reduce electrical resistance.

  Accordingly, the present invention is to solve the above-described conventional problems, and in particular, in a physical quantity sensor such as an acceleration sensor formed using an SOI substrate, the airtightness is improved and the displacement amount of the electrode pad and the movable part is detected. It is an object of the present invention to provide a physical quantity sensor capable of simultaneously obtaining a reduction in electrical resistance with a detection unit.

The present invention relates to a physical quantity sensor formed using an SOI substrate comprising a support substrate / insulating layer / SOI layer.
The SOI layer includes a movable part positioned above the support substrate from which the insulating layer has been removed, a support part that supports the movable part and is formed on the insulating layer, and a displacement amount of the movable part. The detection part for detecting is formed,
A wiring layer formed of metal extends from the electrical connection position with the detection unit on the insulating layer with a thickness smaller than that of the SOI layer, and an electrode pad formed of metal at the tip of the wiring layer is provided. Connected,
A side wall portion of a lid that covers the movable portion, the support portion, and the detection portion is joined to a position crossing the insulating layer and the wiring layer around the SOI layer, and the lid The electrode pad is exposed outside the side wall of the body.

  As a result, the junction step with respect to the side wall of the lid can be made smaller than before, and the wiring path of the wiring layer made of metal can be made shorter than before. Therefore, the airtightness can be improved as compared with the conventional structure, and the electrical resistance between the detection unit and the electrode pad can be reduced.

  In the present invention, the insulating layer for protecting the insulating layer located under the side wall portion of the lid from the isotropic etching process between the side wall portion and the insulating layer and the wiring layer. A protective layer is preferably formed. Thereby, the insulating layer below the side wall portion of the lid body remains without being removed, and the junction step with respect to the side wall portion of the lid body can be more effectively reduced as compared with the conventional case.

  Further, in the present invention, the detection unit includes comb-shaped movable electrodes and fixed electrodes that are alternately arranged in parallel, and the movable electrode is positioned above the support substrate from which the insulating layer has been removed. And the fixed electrode is fixedly supported on the insulating layer apart from the movable part, and the displacement amount of the movable part is a change in capacitance between the movable electrode and the fixed electrode. The structure can be detected based on Thereby, a capacitance type physical sensor can be configured.

  In the present invention, it is preferable that the wiring layer is formed in a recess formed on the surface of the insulating layer. Thereby, the junction level | step difference with respect to the side wall part of the said cover body can be made small more effectively than before.

The present invention relates to a method of manufacturing a physical quantity sensor formed using an SOI substrate comprising a support substrate / insulating layer / SOI layer.
Forming a movable part on the SOI layer, a support part for supporting the movable part, and a detection part for detecting a displacement amount of the movable part, and removing the unnecessary SOI layer;
Forming a wiring layer electrically connected to the detection unit on the exposed insulating layer with a metal;
Forming an electrode pad with a metal at the tip of the wiring layer;
Removing the insulating layer located between the movable part and the support substrate by an isotropic etching process;
Using a lid having a recess formed on the back surface from the side wall, the movable portion and the detection unit are housed in the recess, and the side wall is placed on the insulating layer around the SOI layer, and Bonding to a position crossing over the wiring layer, exposing the electrode pad outside the sidewall portion;
It is characterized by having.

Alternatively, the present invention relates to a method of manufacturing a physical quantity sensor formed using an SOI substrate comprising a support substrate / insulating layer / SOI layer.
Leaving the SOI layer necessary to form a movable part, a support part for supporting the movable part, and a detection part for detecting a displacement amount of the movable part in the SOI layer, and removing the unnecessary SOI layer;
Forming a wiring layer for electrically connecting to the detection unit on the exposed insulating layer with a metal;
Forming an electrode pad with a metal at the tip of the wiring layer;
Forming the movable part, the support part, and the detection part in the remaining SOI layer;
Removing an insulating layer located between the movable part and the support substrate by an isotropic etching process;
The movable body and the detection unit are housed in the recess using a lid having a recess formed on the back surface from the side wall, and the side wall is placed on the insulating layer around the SOI layer and the Bonding to a position crossing over the wiring layer, exposing the electrode pad outside the side wall,
It is characterized by having.

  According to the present invention, it is possible to easily and appropriately reduce the joining step with respect to the side wall portion of the lid body as compared with the conventional case, and to form the wiring path of the wiring layer made of metal shorter than the conventional one.

  In the present invention, a comb-like movable electrode and a fixed electrode, which are alternately arranged, are provided, and the detection unit for detecting the displacement amount of the movable unit based on a change in capacitance is formed. The movable electrode is integrally formed on a side end portion of the movable portion, the fixed electrode is formed away from the movable portion, and the isotropic etching step is performed between the movable electrode and the support substrate. While the insulating layer located is removed, the fixed electrode can be formed in a structure that is fixedly supported on the insulating layer.

  Further, in the present invention, before the isotropic etching step, an insulating protective layer for protecting from the isotropic etching step is formed on at least the insulating layer in the junction region of the side wall, and thereafter It is preferable to perform the isotropic etching step and provide a side wall portion of the lid on the protective layer. Thereby, the junction level | step difference with respect to the said side wall part can be reduced more effectively.

  In the present invention, the wiring layer is preferably formed by sputtering. As a result, the wiring layer can be formed appropriately and easily with a thin film thickness.

  In the present invention, it is preferable that the electrode pad is formed by overlapping a metal layer on or below the tip of the wiring layer.

  According to the physical quantity sensor of the present invention, it is possible to reduce the joining step with respect to the side wall portion of the lid as compared with the conventional case, and it is possible to shorten the wiring path of the wiring layer formed of metal. Therefore, the airtightness can be improved as compared with the conventional structure, and the electrical resistance between the detection unit and the electrode pad can be reduced.

  FIG. 1 is a plan view of an acceleration sensor according to the present embodiment (however, the lid shows a side wall with a dotted line), and FIG. 2 shows the acceleration sensor shown in FIG. FIG. 3 and FIG. 4 are cross-sectional views of an acceleration sensor according to another embodiment partially different from FIG. 2.

The acceleration sensor 1 shown in FIG. 1 is formed using an SOI (Silicon on Insulator) substrate 2. The SOI substrate 2 includes a support substrate 3 made of silicon, an SOI layer 5 made of a silicon layer, and an insulating layer 4 made of, for example, SiO ₂ located between the support substrate 3 and the SOI layer 5. This is a laminated structure. The support substrate 3 has a thickness of 0.4 to 0.7 mm, the insulating layer 4 has a thickness of 1 to 2 μm, and the SOI layer 5 has a thickness of 10 to 30 μm.

  As shown in FIGS. 1 and 2, the SOI layer 5 is formed with a movable part 6, a support part 10 that supports the movable part 6, and a detection part 12 for detecting the amount of displacement of the movable part 6. .

  As shown in FIG. 1, the movable portion 6 includes a weight portion 7 and spring portions 9 formed on both sides of the weight portion 7 in the X direction in the drawing. A support portion 10 is formed of an SOI layer 5 on the opposite side of the spring portion 9 from the weight portion 7, and the support portion 10 is fixedly supported on the insulating layer 4.

  The detection unit 12 is provided as a pair of counter electrodes that is long in the Y direction of the movable unit 6. The detection unit 12 includes a movable electrode 8 and a fixed electrode 11. The movable electrode 8 has a comb shape and is formed integrally with the movable portion 6 at a predetermined interval in the X direction in the drawing. On the other hand, the fixed electrode 11 has a predetermined interval in the X direction in the figure, and includes a comb-like portion 11a that is alternately arranged in parallel with the movable electrode 8, and a connecting portion 11b that connects the comb-like portion 11a. Is done. The fixed electrode 11 is separated from the movable portion 6, and at least a part of the connecting portion 11 b is fixedly supported on the insulating layer 4.

  As shown in FIGS. 1 and 2, the insulating layer 4 is not formed between the movable portion 6 and the movable electrode 8 and the support substrate 3, and a space S <b> 1 is formed. The space S1 is also formed under the comb-like portion 11a of the fixed electrode 11.

  As described above, the SOI layer 5 is left only in the movable part 6, the detection part 12, and the support part 10, and is not left in other places. The insulating layer 4 is left on the support substrate 3 except for the region where the space S1 is formed.

  As shown in FIGS. 1 and 2, a wiring layer 13 electrically connected to the fixed electrode 11 and one support portion 10 is formed on the insulating layer 4 so as to extend in the X direction in the drawing. The wiring layer 13 connected to the support portion 10 is in a state of being electrically connected to the movable electrode 8. The wiring layer 13 is made of metal, for example, formed by sputtering. The wiring layer 13 is thinner than the SOI layer 5. As described above, the thickness of the SOI layer 5 is 10 to 30 μm, while the thickness of the wiring layer 13 is 0.1 to 2 μm. The wiring layer 13 is made of Al, Au, or the like. Alternatively, a laminated structure with Ti, Ta, Cu or the like as an adhesion layer or a barrier layer may be used.

  As shown in FIG. 2, the tip 13a of the wiring layer 13 constitutes a part of the electrode pad 14 formed in a rectangular shape having a large area. The electrode pad 14 has a structure in which a metal layer 15 made of Al, Au, or the like is laminated on or under the tip portion 13 a of the wiring layer 13. The metal layer 15 is, for example, an Au plating layer.

As shown in FIGS. 1 and 2, an insulating protective layer 16 is formed on the insulating layer 4 and the wiring layer 13. The protective layer 16 needs to be made of a material that is not removed in an isotropic etching process by wet etching or dry etching. The protective layer 16 is formed by sputtering or CVD with Al ₂ O ₃ or SiN. As shown in FIG. 2, when the insulating layer 4 below the movable part 6 and the movable electrode 8 is removed by an isotropic etching process to form the space S1, the protective layer 16 is similarly formed with the SOI. The insulating layer 4 extending around the layer 5 is provided so as not to be removed.

  As shown in FIGS. 1 and 2, a side wall portion 17 a protruding downward from the periphery is formed on the back surface side of the lid 17 that covers the movable portion 6, the support portion 10, and the detection portion 12. A concave portion 17b surrounded by the side wall portion 17a is formed. The lid 17 covers the movable part 6, the support part 10, and the detection part 12, so that a space S <b> 2 is formed between the lid 17 and the movable part 6. Although the material of the said cover body 17 is not limited, For example, it forms with glass or silicon | silicone.

  As shown in FIGS. 1 and 2, the side wall portion 17 a of the lid body 17 is provided on the protective layer 16 extending around the SOI layer 5 and is formed so as to cross over the wiring layer 13. Thus, the electrode pad 14 is exposed outside the side wall portion 17a. For example, the side wall portion 17a is joined to the protective layer 16 via an adhesive layer.

  In the acceleration sensor 1 shown in FIGS. 1 and 2, when acceleration occurs and the movable portion 6 is displaced in a direction parallel to the X direction in the drawing, the distance between the movable electrode 8 and the fixed electrode 11 changes. The capacitance changes, and the displacement of the movable portion 6 can be detected based on the capacitance change. In the form of FIG. 1, the relative position of each comb tooth of one fixed electrode 11 and each of the other fixed electrode 11 with respect to each comb tooth of two sets of movable electrodes 8 provided in the movable portion 6. The relative position of the comb teeth is a direction parallel to the X direction in the figure and is shifted in different directions. Therefore, when the movable part 6 is displaced, the capacitance change between the movable electrode 8 and the fixed electrode 11 is different on both sides of the movable part 6, and as a result, highly accurate displacement detection is performed by differential detection. It can be performed and the direction of acceleration can be detected.

The acceleration sensor 1 according to this embodiment shown in FIGS. 1 and 2 has the following characteristic points.
In the SOI layer 5, a movable part 6 located above the support substrate 3 from which the insulating layer 4 has been removed, a support part 10 that supports the movable part 6, and a displacement amount of the movable part 6 are detected. Therefore, the SOI layer 5 is not left in any other place.

As shown in FIGS. 1 and 2, a wiring layer 13 made of metal extends below the protective layer 16 formed on the insulating layer 4 with a film thickness thinner than the SOI layer 5, and the wiring An electrode pad 14 is formed on the tip 13 a of the layer 13.
Thereby, the wiring resistance of the wiring layer 13 made of metal can be kept low.

  Further, in the present embodiment, the insulating layer 4 having a flat surface is exposed around the movable portion 6 except for the unnecessary SOI layer 5, and the lid 17 is formed on the insulating layer 4 via the protective layer 16. The side wall part 17a is joined. In the portion where the wiring layer 13 is formed, the side wall portion 17a is provided so as to cross over the wiring layer 13. However, the wiring layer 13 is thinner than the SOI layer 5 and the wiring layer 13 is thin. The uneven step due to forming 13 can be reduced.

  Therefore, the joining step with respect to the side wall part 17a of the said cover body 17 can be made small compared with the past.

  As described above, according to the configuration of the acceleration sensor 1 of the present embodiment, airtightness can be improved as compared with the conventional case, the bonding strength of the lid body 17 to the SOI substrate 2 can be increased, and the detection unit The electrical resistance between the electrode 12 and the electrode pad 14 can be reduced.

  As shown in FIGS. 1 and 2, the electrode pad 14 is exposed outside the side wall portion 17 a of the lid body 17. Since the electrode pad 14 is composed of the tip portion 13a of the wiring layer 13 and the metal layer 15 formed by plating, for example, the wire bonding property of the pad portion is stabilized, and the electrical connection between the detection portion 12 and the electrode pad 14 is stabilized. The resistance can be reduced more effectively, and the film thickness can be reduced at portions other than where the electrode pad 14 is formed. The film thickness of the electrode pad 14 is about 0.5 to 2 μm.

  In the embodiment shown in FIGS. 1 and 2, the protective layer 16 is formed over the insulating layer 4 and the wiring layer 13 extending around the SOI layer 5, but for example, as shown in FIG. The protective layer 16 may be formed only on the insulating layer 4 and the wiring layer 13 which become the bonding region of the side wall portion 17a. In this case, the insulating layer 4 exposed without being covered with the protective layer 16, the wiring layer 13, the electrode pad 14 and the like is the same when the insulating layer 4 under the movable portion 6 is subjected to an isotropic etching process. However, at least a portion of the insulating layer 4 that becomes a bonding region of the side wall portion 17a can be left. However, as shown in FIGS. 1 and 2, it is easier to form the lid 17 on the protective layer 16 if the protective layer 16 is formed over the entire area of the insulating layer 4 extending around the SOI layer 5. It can be suitably joined.

  As shown in FIG. 4, when the wiring layer 13 is formed in the recess 4 a formed on the surface of the insulating layer 4, the step difference between the lid 17 and the side wall 17 a can be effectively reduced. .

  In particular, if the thickness of the wiring layer 13 and the depth of the recess 4a are controlled so that the surface 13b of the wiring layer 13 and the surface 4b of the insulating layer 4 are on the same plane, the bonding region to the side wall portion 17a. Can be flattened with high accuracy, the airtightness of the lid 17 can be improved more effectively, and the bonding strength of the lid 17 to the SOI substrate 2 can be more effectively increased. In addition to the bonding by the adhesive layer, other substrate bonding techniques such as room temperature bonding can be used as the bonding method of the lid body 17.

  A method of manufacturing the acceleration sensor 1 according to this embodiment will be described with reference to FIGS. (A) of each figure is a top view of the acceleration sensor 1 in a manufacturing process, (b) shows sectional drawing in the same position as FIG.

  In the process shown in FIG. 5, the movable portion 6, the support portion 10 that supports the movable portion 6, and the detection portion 12 are formed on the SOI layer 5 of the SOI substrate 2 that is composed of the support substrate 3 / insulating layer 4 / SOI layer 5. The necessary SOI layer 5 is left, and the other unnecessary SOI layer 5 is removed by dry etching. The insulating layer 4 is exposed at the removed portion.

  Next, in the step shown in FIG. 6, the metal wiring layer 13 that is electrically connected to the movable electrode 8 and the fixed electrode 11 constituting the detection unit 12 on the exposed insulating layer 4 is thinner than the SOI layer 5. It is formed with a film thickness. At this time, the wiring layer 13 is preferably formed by sputtering. The wiring layer 13 is made of, for example, Al.

  In the step shown in FIG. 5, the tip portion 13a of the wiring layer 13 is formed in a rectangular electrode pad shape having a large area, and the metal layer 15 plated with Au or the like is further formed on the tip portion 13a. In this embodiment, an electrode pad 14 is constituted by the tip portion 13 a of the wiring layer 13 and the metal layer 15.

7, the SOI layer 5 and the electrode pad 14 are protected by, for example, a resist layer (not shown), and the insulating layer 4 and the wiring layer not covered with the resist layer are protected. An insulating protective layer 16 made of Al ₂ O ₃ , SiN or the like is formed on the film 13 by sputtering or CVD, for example. The protective layer 16 is formed of a material that is not removed in an isotropic etching process performed in a later step of FIG.

  Subsequently, in the process shown in FIG. 8, the SOI layer 5 left in the process of FIG. 5 is composed of the movable part 6 including the weight part 7 and the spring part 9, the support part 10, and the movable electrode 8 and the fixed electrode 11. The detection unit 12 is formed by dry etching. At this time, a large number of fine holes (not shown) leading to the insulating layer 4 are formed in the weight portion 7.

  Subsequently, in the process shown in FIG. 9, the insulating layer 4 formed between the movable part 6 and the support substrate 3 is removed by an isotropic etching process. As described above, since a large number of fine holes are formed in the weight part 7, the insulating layer 4 below the movable part 6 is appropriately removed through an isotropic etching process through the fine holes. Can do. Further, the portion of the insulating layer 4 from the exposed portion between the comb-like portion 11a of the movable electrode 8 and the fixed electrode 11 to the lower portion of the movable electrode 8 and the comb-like portion 11a of the fixed electrode 11 is also subjected to the isotropic etching process. Removed. However, the insulating layer 4 under the protective layer 16, under the electrode pad 14, under the support portion 10, and at least under the coupling portion 11 b of the fixed electrode 11 is removed in the isotropic etching process. Left behind.

  Subsequently, in the step shown in FIG. 10, the movable portion 6, the side wall 17 a is formed so as to protrude downward from the periphery of the back surface, and the movable body 6, the lid 6 has a recess 17 b surrounded by the side wall 17 a. The detection unit 12 and the support unit 10 are housed in the recess 17b. At this time, the side wall portion 17a of the lid body 17 is joined to the protective layer 16 formed on the insulating layer 4 extending around the movable portion 6 via, for example, an adhesive layer (not shown), and the wiring layer The electrode pad 14 is exposed outside the side wall portion 17a.

  In the method for manufacturing the acceleration sensor 1 described above, the SOI layer 5 that is roughly required is left in the process of FIG. 5, and the movable part 6, the detection part 12, and the support are supported on the remaining SOI layer 5 in the process of FIG. 8. Although the portion 10 is formed, as shown in FIG. 11, the movable portion 6, the fixed electrode 11, and the support portion 10 may be precisely formed by dry etching with respect to the SOI layer 5 from the beginning. After the step of FIG. 11, the manufacturing process may be advanced in the order of FIGS. 6, 7, 9, and 10.

  In the step of FIG. 7, the insulating protective layer 16 is formed on the entire insulating layer 4 and the wiring layer 13 except for the remaining SOI layer 5 and electrode pad 14, but as shown in FIG. In addition, in the step of FIG. 10, the protective layer 16 may be provided only on the insulating layer 4 and the wiring layer 13 which are to be joined regions of the side wall portion 17 a of the lid body 17. At this time, the width of the protective layer 16 is made larger than the width of the side wall portion 17a, so that the insulating layer 4 is appropriately left under the protective layer 16 even by wraparound by an isotropic etching process. be able to. It is preferable that the side wall 17a has a width of 50 to 200 μm, and the protective layer 16 has a width of 100 to 300 μm.

  When the manufacturing process shown in FIG. 12 is used, in the isotropic etching process of FIG. 9, the insulating layer 4 spreading around the SOI layer 5 exposed without being covered with the protective layer 16 is also isotropic. Although it will be removed in the etching step, the frame-shaped insulating layer 4 and protective layer 16 may be left as a joining region with the side wall portion 17a of the lid 17 as shown in FIG. However, as shown in FIG. 7, it is easier and more appropriate to form the protective layer 16 on the exposed insulating layer 4 that spreads around the SOI layer 5 in the process shown in FIG. 10. It is suitable to be performed.

  In the present embodiment, for example, the protective layer is not formed in the step of FIG. 7, and the SOI layer 5 from which the insulating layer 4 is removed after the isotropic etching step of FIGS. 8 and 9 is performed. An insulating layer may be newly formed on the surrounding support substrate 3. However, it is preferable to provide the manufacturing process of the protective layer 16 of FIG. 7 because the manufacturing process can be simplified and the lid 17 can be easily and appropriately joined in the process of FIG.

  Further, in order to form the acceleration sensor 1 of the form shown in FIG. 4, the recess 4a is formed by dry etching on the exposed surface of the insulating layer 4 after the step of FIG. 5 and before the step of FIG. The wiring layer 13 may be formed in the recess 4a.

  Further, as shown in FIG. 13, a large number of acceleration sensors can be formed simultaneously. In FIG. 13, the movable portion 6, the wiring layer 13, the electrode pad 14, and the like are omitted.

A large number of acceleration sensors are formed on the SOI substrate 2 based on the steps shown in FIGS. 5 to 9, and then a lid assembly 30 to which a large number of lids 17 are connected is formed on the SOI substrate 2 as shown in FIG. 13. Cover and join. And many acceleration sensors can be obtained simultaneously by cut | disconnecting from the part of the dashed-dotted line shown in FIG.
The above-described method for manufacturing an acceleration sensor according to this embodiment has the following characteristic features.

  In this embodiment, the SOI layer 5 is formed with a movable part 6, a support part 10 that supports the movable part 6, and a detection part 12 for detecting the amount of displacement of the movable part 6, and other unnecessary SOI layers. There is a step of removing 5.

  Next, a step of forming a wiring layer 13 and an electrode pad 14 having a thickness smaller than that of the SOI layer 5 electrically connected to the detection unit 12 on the insulating layer 4 exposed by removing the SOI layer 5 with a metal. is there.

  Then, after the insulating layer 4 located between the movable part 6 and the support substrate 3 is removed by an isotropic etching process, the movable part 6 and the detection part 12 are connected to the lid by the lid 17. There is a step of storing in the recess formed in the member 17. At this time, in this embodiment, the side wall portion 17a of the lid body 17 is joined to a position crossing the insulating layer 4 and the wiring layer 13 around the movable portion 6, and the side wall portion 17a The electrode pad 14 is exposed outside.

  As described above, in the present embodiment, most of the junction region with respect to the side wall portion 17a of the lid body 17 can be formed on the flat insulating layer 4 and partly overlaps with the wiring layer 13, but the wiring layer 13 has a portion. The film thickness is thinner than that of the SOI layer 5, and the junction step with respect to the side wall portion 17 a can be made smaller than in the prior art. In addition, since the wiring layer 13 made of metal is formed to extend on the insulating layer 4, the wiring path from the detection unit 12 to the electrode pad 14 can be formed shorter than before. As described above, the airtightness can be improved as compared with the conventional case, the bonding strength of the lid 17 to the SOI substrate 2 can be increased, and the electrical resistance between the detection unit 12 and the electrode pad 14 can be reduced. The possible acceleration sensor 1 can be manufactured easily and appropriately.

  In the present embodiment, the SOI layer 5 may be left in the electrode pad 14, but the electrode pad 14 is placed on the tip 13 a of the wiring layer 13 made of metal. By being formed in an overlapping manner, the electrical resistance between the detection unit 12 and the electrode pad 14 can be reduced more effectively, and the portion of the electrode pad 14 exposed outside the side wall portion 17a of the lid body 17 can be reduced. A thin film can be formed.

  In this embodiment, as shown in FIG. 7, a protective layer 16 is formed on the insulating layer 4 extending around the SOI layer 5 to protect it from the isotropic etching process, and then the isotropic etching process. It is preferable that the side wall portion 17 a of the lid body 17 is bonded onto the protective layer 16. Accordingly, the insulating layer 4 can be appropriately left below the side wall portion 17a of the lid body 17, and the joining step with respect to the side wall portion 17a of the lid body 17 can be more effectively reduced as compared with the conventional case. .

The acceleration sensor 1 described above is a capacitance type, but may be a piezoresistive type using a piezo element as a detection unit. The acceleration sensor 1 described above is a single-axis type that can detect only when the movable portion 6 is displaced in a direction parallel to the X direction shown in the drawing. Even a biaxial type capable of detecting displacement in a direction parallel to these two directions, or a triaxial type capable of detecting displacement in directions parallel to the X direction, Y direction and Z direction shown in the drawing. Good.
This embodiment can be applied not only to an acceleration sensor but also to an angular velocity sensor or the like.

The top view of the acceleration sensor in this embodiment (however, the lid body shows the side wall part with a dotted line), FIG. 1 is a cross-sectional view of the acceleration sensor shown in FIG. 1 cut along the film thickness direction (Z direction) from line AA and viewed in the arrow direction; FIG. 2 is a cross-sectional view of an acceleration sensor of another embodiment that is partially different from FIG. FIG. 2 is a cross-sectional view of an acceleration sensor of another embodiment that is partially different from FIG. 1 process drawing which shows the manufacturing process of the acceleration sensor of this embodiment, FIG. 5 is a process diagram that is performed next to FIG. FIG. 6 is a process diagram performed next to FIG. 7 is a process diagram to be performed next to FIG. 8 is a process diagram performed next to FIG. FIG. 9 is a process diagram performed next to FIG. One process diagram to replace the process of FIG. Figure 7 shows a process diagram that can be used instead of the process. One process diagram (the figure is simplified) showing a process in which a plurality of acceleration sensors can be formed simultaneously,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Acceleration sensor 2 SOI substrate 3 Support substrate 4 Insulating layer 5 SOI layer 6 Movable part 7 Weight part 8 Movable electrode 9 Spring part 10 Support part 11 Fixed electrode 12 Detection part 13 Wiring layer 14 Electrode pad 16 Protective layer 17 Lid 17a ( Side wall 30 of lid) lid assembly

Claims (10)

In a physical quantity sensor formed using an SOI substrate comprising a support substrate / insulating layer / SOI layer,
The SOI layer includes a movable part positioned above the support substrate from which the insulating layer has been removed, a support part that supports the movable part and is formed on the insulating layer, and a displacement amount of the movable part. The detection part for detecting is formed,
A wiring layer formed of metal extends from the electrical connection position with the detection unit on the insulating layer with a film thickness thinner than that of the SOI layer, and an electrode pad formed of metal is formed at the tip of the wiring layer. Connected,
A side wall portion of a lid that covers the movable portion, the support portion, and the detection portion is joined to a position crossing the insulating layer and the wiring layer around the SOI layer, and the lid A physical quantity sensor, wherein the electrode pad is exposed outside a side wall of the body.   An insulating protective layer is formed between the sidewall portion and the insulating layer and the wiring layer to protect the insulating layer located under the sidewall portion of the lid from an isotropic etching process. The physical quantity sensor according to claim 1.   The detection unit includes comb-shaped movable electrodes and fixed electrodes that are alternately arranged in parallel, and the movable electrode is positioned above the support substrate from which the insulating layer has been removed and the movable unit. The fixed electrode is fixedly supported on the insulating layer apart from the movable part, and the displacement amount of the movable part is detected based on a capacitance change between the movable electrode and the fixed electrode. The physical quantity sensor according to claim 1 or 2.   The physical quantity sensor according to claim 1, wherein the wiring layer is formed in a recess formed on a surface of the insulating layer. In a manufacturing method of a physical quantity sensor formed using an SOI substrate comprising a support substrate / insulating layer / SOI layer,
Forming a movable part on the SOI layer, a support part for supporting the movable part, and a detection part for detecting a displacement amount of the movable part, and removing the unnecessary SOI layer;
Forming a wiring layer electrically connected to the detection unit on the exposed insulating layer with a metal;
Forming an electrode pad with a metal at the tip of the wiring layer;
Removing the insulating layer located between the movable part and the support substrate by an isotropic etching process;
Using a lid having a recess formed on the back surface from the side wall, the movable portion and the detection unit are housed in the recess, and the side wall is placed on the insulating layer around the SOI layer, and Bonding to a position crossing over the wiring layer, exposing the electrode pad outside the sidewall portion;
A method of manufacturing a physical quantity sensor, comprising: In a manufacturing method of a physical quantity sensor formed using an SOI substrate comprising a support substrate / insulating layer / SOI layer,
Leaving the SOI layer necessary to form a movable part, a support part for supporting the movable part, and a detection part for detecting a displacement amount of the movable part in the SOI layer, and removing the unnecessary SOI layer;
Forming a wiring layer for electrically connecting to the detection unit on the exposed insulating layer with a metal;
Forming an electrode pad with a metal at the tip of the wiring layer;
Forming the movable part, the support part, and the detection part in the remaining SOI layer;
Removing an insulating layer located between the movable part and the support substrate by an isotropic etching process;
The movable body and the detection unit are housed in the recess using a lid having a recess formed on the back surface from the side wall, and the side wall is placed on the insulating layer around the SOI layer and the Bonding to a position crossing over the wiring layer, exposing the electrode pad outside the side wall,
A method of manufacturing a physical quantity sensor, comprising:   Comb-like movable electrodes and fixed electrodes that are alternately arranged, and forming the detection unit for detecting a displacement amount of the movable unit based on a change in capacitance, wherein the movable electrode is While forming integrally with the movable part, forming the fixed electrode away from the movable part, and removing the insulating layer located between the movable electrode and the support substrate in the isotropic etching step The method of manufacturing a physical quantity sensor according to claim 5 or 6, wherein the fixed electrode is held in a state of being fixedly supported on the insulating layer.   Before the isotropic etching step, at least an insulating protective layer for protecting from the isotropic etching step is formed on the insulating layer in the bonding region of the side wall, and then the isotropic The method of manufacturing a physical quantity sensor according to claim 5, wherein an etching step is performed to provide a side wall portion of the lid on the protective layer.   The method of manufacturing a physical quantity sensor according to claim 5, wherein the wiring layer is formed by sputtering.   10. The method of manufacturing a physical quantity sensor according to claim 5, wherein the electrode pad is formed by overlapping a metal layer on or below a tip portion of the wiring layer.

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