JP2010147285A - Mems, vibration gyroscope, and method of manufacturing mems - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To expand a region in an MEMS, where a piezoelectric element can be arranged. <P>SOLUTION: The MEMS includes: a flexible portion which includes an insulating layer having a plurality of contact holes formed and a semiconductor layer coming into contact with the insulating layer, and having flexibility; a plurality of conductors formed of a plurality of impurity diffusion regions formed in the semiconductor layer and separated from one another; a piezoelectric layer including a lower electrode layer laminated on a surface of the insulating layer and coming into contact with the conductors through the contact holes, a piezoelectric layer laminated on a surface of the lower electrode layer, and an upper electrode layer laminated on a surface of the piezoelectric layer, the piezoelectric element being positioned on the flexible portion; and a connection means formed of a conductor layer for connecting the upper electrode layer to the conductors through the contact holes formed at the flexible portion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a MEMS (Micro Electro Mechanical Systems), a vibrating gyroscope, and a method for manufacturing a MEMS.

Conventionally, MEMS such as an acceleration sensor and a piezoelectric actuator provided with a piezoelectric element are known (for example, see Patent Documents 1 and 2). In Patent Documents 1 and 2, a method of forming a wiring element by diffusing impurity ions in a part of a silicon substrate or a piezoelectric layer is formed.
JP 9-2111020 A JP 2006-217715 A

However, according to the method described in Patent Document 1, since the common signal line constituting the electrode of the piezoelectric element is in contact with the silicon substrate, the piezoelectric element can be obtained even if impurity ions are diffused in the surface layer of the silicon substrate. It is impossible to form a plurality of conductors separated from each other immediately below the line. In addition, according to the method described in Patent Document 2, it is not possible to form the mutually separated conductors drawn from the electrodes of the piezoelectric element on the elastic film in contact with the piezoelectric element.
Therefore, according to the methods described in Patent Documents 1 and 2, it is not possible to overlap all the conductive wire patterns drawn from the piezoelectric elements with the patterns of the piezoelectric elements. That is, according to the methods described in Patent Documents 1 and 2, since the piezoelectric element has to be arranged avoiding the conducting wire drawn from the piezoelectric element, the area where the piezoelectric element can be arranged is reduced.

  An object of the present invention is to expand the area where the piezoelectric element can be arranged in the MEMS.

  (1) The MEMS for achieving the above object is formed on the semiconductor layer, and includes a flexible portion including an insulating layer in which a plurality of contact holes are formed and a semiconductor layer in contact with the insulating layer, and a flexible portion. A plurality of conductive wires made of a plurality of impurity diffusion regions and separated from each other; a lower electrode layer that is stacked on the surface of the insulating layer and is in contact with the conductive wire through the contact hole; and a lower electrode layer that is stacked on the surface of the lower electrode layer A piezoelectric element including a piezoelectric layer and an upper electrode layer laminated on a surface of the piezoelectric layer; the piezoelectric element positioned on the flexible portion; and the upper electrode layer and the conductive wire through the contact hole formed in the flexible portion. Connecting means comprising a conductive layer for connecting the two.

  According to the present invention, since the semiconductor layer and the piezoelectric layer are separated from each other via the insulating layer, a plurality of conductive wires made of impurity diffusion regions of the semiconductor layer can be disposed directly below the piezoelectric element. Therefore, according to the present invention, the area where the piezoelectric element can be arranged is expanded, the driving force of the actuator is improved, and the sensor sensitivity is improved. In the present specification, the terms “upper” and “lower” are used with the arrangement position of the piezoelectric element with respect to the flexible portion as the upper side.

(2) In the MEMS for achieving the above object, the pattern of the piezoelectric layer may be wider than the pattern of the lower electrode layer and may be in contact with the insulating layer around the lower electrode layer.
According to the present invention, it is possible to prevent a short circuit and a leak between the upper electrode and the lower electrode of the piezoelectric element.

(3) In the MEMS for achieving the above object, the piezoelectric layer has a lower surface forming an interface with the lower electrode layer and the insulating layer wider than an upper surface forming an interface with the upper electrode layer, The side surface between the upper surfaces may be an inclined surface, and the connection means may be laminated on the side surface of the piezoelectric layer.
According to the present invention, since the piezoelectric layer itself is used as an interlayer insulating film, the structure can be simplified and the manufacturing cost can be reduced. When the piezoelectric layer is an inclined surface, the narrower angle formed by the upper surface and the side surface of the piezoelectric layer is an obtuse angle, and the narrower angle formed by the lower surface and the side surface of the piezoelectric layer is an acute angle.

(4) In the MEMS for achieving the above object, the pattern of the upper electrode layer is narrower than the pattern of the lower electrode layer, and the lower electrode layer or the piezoelectric layer may be exposed from the periphery of the upper electrode layer. Good.
According to the present invention, it is possible to prevent a short circuit between the upper electrode and the lower electrode of the piezoelectric element.

(5) The MEMS for achieving the above object is configured as a vibrating gyroscope further including a weight part and a support part, and the flexible part has a free end coupled to the weight part and a fixed end connected to the weight part. A beam coupled to a support portion is formed, and the piezoelectric element includes a driving piezoelectric element that drives the weight portion by distorting the flexible portion, and a flexible piezoelectric portion that accompanies the movement of the weight portion. You may comprise the detection piezoelectric element which detects distortion.
According to the present invention, in order to reduce the rigidity of the flexible portion and increase the sensitivity, the flexible portion is configured as a beam having a narrow pattern, and the piezoelectric element can be arranged to the maximum with respect to the flexible portion having a narrow pattern. A highly sensitive vibration gyroscope can be realized.

(6) A MEMS manufacturing method for achieving the above object includes forming a plurality of contact holes in an insulating layer stacked on a surface of a semiconductor layer, and including the insulating layer and the semiconductor layer, and having flexibility. Forming a flexible portion and forming a plurality of conductive wires composed of a plurality of impurity diffusion regions exposed from the plurality of contact holes in the semiconductor layer, stacked on a surface of the insulating layer and contacting the conductive wires through the contact holes; Forming a piezoelectric element including an electrode layer, a piezoelectric layer laminated on a surface of the lower electrode layer, and an upper electrode layer laminated on the surface of the piezoelectric layer, and positioned on the flexible portion; Forming a conducting wire layer connecting the upper electrode layer and the conducting wire.
According to the present invention, the semiconductor layer and the piezoelectric layer are separated from each other with the insulating layer interposed therebetween, so that a plurality of conductive wires composed of impurity diffusion regions of the semiconductor layer can be disposed directly below the piezoelectric element. Therefore, according to the present invention, the area where the piezoelectric element can be arranged is enlarged.

  The order of the operations described in the claims is not limited to the order of description as long as there is no technical obstruction factor, and may be executed at the same time, may be executed in the reverse order of the description order, or may be continuous. It does not have to be executed in order. Further, the order of the operations described in the claims is not limited to the order of description as long as there is no technical obstruction factor, and may be executed at the same time, may be executed in the reverse order of the description order, or may be continuous. It does not have to be executed in order.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the corresponding component in each figure, and the overlapping description is abbreviate | omitted.
1. First embodiment (Configuration)
A vibrating gyroscope which is a first embodiment of the MEMS sensor of the present invention is shown in FIGS. 1A and 1B are sectional views showing a sensor die 1A of the vibrating gyroscope 1, and are sectional views taken along lines AA and BB shown in FIG. 1C, respectively. FIG. 1C is a top view of the sensor die 1A. FIG. 2 is a cross-sectional view showing the vibrating gyroscope 1. In FIG. 1A, FIG. 1B, and FIG. 2, the interface of the layer which comprises the sensor die 1A is shown with the broken line, and the boundary of the mechanical component which comprises the sensor die 1A is shown with the continuous line.

  The vibrating gyroscope 1 is a MEMS sensor for detecting three-axis angular velocity components orthogonal to each other. The vibrating gyroscope 1 includes a package 1B shown in FIG. 2 and a sensor die 1A housed in the package 1B.

As shown in FIG. 1A, the sensor die 1A includes a base layer 11, an etching stopper layer 12 in contact with the base layer 11, a semiconductor layer 13 in contact with the etching stopper layer 12, a first insulating layer 20 in contact with the semiconductor layer 13, An electrode layer 31 in contact with the first insulating layer 20, a piezoelectric layer 32 in contact with the electrode layer 31, an electrode layer 33 in contact with the piezoelectric layer 32, a first layer in contact with the electrode layers 31, 33, the piezoelectric layer 32, and the first insulating layer 20. This is a laminated structure composed of two insulating layers 40 and a surface conductive layer 50 in contact with the second insulating layer 40. Both the base layer 11 and the semiconductor layer 13 are made of single crystal silicon (Si). The base layer 11 may be made of a bulk material such as glass. The thickness of the base layer 11 is 625 μm. The thickness of the semiconductor layer 13 is 10 μm. The etching stopper layer 12 and the first insulating layer 20 are made of a silicon oxide film (SiO ₂ ). The thickness of the etching stopper layer 12 is 1 μm. The thickness of the first insulating layer 20 is 0.5 μm. The electrode layers 31 and 33 are made of platinum (Pt). The electrode layers 31 and 33 may be made of a conductive material such as iridium (Ir), iridium oxide (IrO ₂ ), or gold (Au). The electrode layers 31 and 33 have a thickness of 0.1 μm. The piezoelectric layer 32 is made of PZT (lead zirconate titanate). The thickness of the piezoelectric layer 32 is 3 μm. The second insulating layer 40 is made of photosensitive polyimide. The second insulating layer 40 may be made of an inorganic insulating material such as a silicon oxide film, a silicon nitride film (Si _x N _y ), or alumina (Al ₂ O ₃ ). The thickness of the second insulating layer 40 is 5 μm. The surface conducting wire layer 50 is made of aluminum (Al). The surface conducting wire layer 50 may be made of a conductive material such as aluminum silicon (AlSi) or AlSiCu. The thickness of the surface conducting wire layer 50 is 0.5 μm.

  The sensor die 1A of the vibrating gyroscope 1 includes a frame-shaped support portion S, four beams F arranged in a cross shape inside the support portion S, and weights coupled to the free ends of the four beams F. The piezoelectric element 30a for driving to vibrate the weight part M by bending the four beams F provided on the part M and the four beams F, respectively, and the four piezoelectric elements provided on the four beams F respectively. And a detecting piezoelectric element 30b for detecting distortion of the beam F.

  The support portion S has a rectangular frame shape as shown in FIG. 1C. The support part S includes a base layer 11, an etching stopper layer 12, a semiconductor layer 13, and a first insulating layer 20. The support portion S includes a thick base layer 11 made of a bulk material, and is fixed to the package 1B via the base layer 11. Therefore, the support portion S behaves as a substantially rigid body that does not move in the coordinate system fixed to the vibrating gyroscope 1. The bottom surface of the support portion S is bonded to the bottom surface of the package 1B via an adhesive layer 92.

  Each of the four beams F as the flexible portion has a cantilever shape. The beam F includes a semiconductor layer 13 and a first insulating layer 20. Since the beam F does not include the thick base layer 11 made of a bulk material, the beam F behaves as a flexible film. One end of each of the four beams F is coupled to four sides inside the support portion S. Since the support portion S behaves as an immovable rigid body, one end of the beam F is a fixed end in the coordinate system fixed to the vibration gyroscope 1. The four beams F protrude from the four sides inside the support part S toward the center of the space inside the support part S. The protruding ends of the four beams F are coupled to the weight portion M. Since the weight M is coupled only to the beam F and floats from the bottom surface 90a of the package 1B as shown in FIG. 2, the protruding end of the beam F behaves as a free end in the coordinate system fixed to the vibrating gyroscope 1. The four beams F are deformed as the weight M moves.

  The bottom surface of the weight portion M has a pattern (a shape viewed from the thickness direction of the beam F) in which one rectangle and four rectangles coupled to the four corners are combined. The weight portion M includes a base layer 11, an etching stopper layer 12, a semiconductor layer 13, and a first insulating layer 20. Since the weight portion M includes the thick base layer 11 made of a bulk material, the weight portion M substantially behaves as a rigid body. Since the weight M is coupled only to the beam F and floats from the bottom surface 90a of the package 1B as shown in FIG. 2, the weight M moves in a coordinate system fixed to the vibrating gyroscope 1.

  Each of the driving piezoelectric element 30 a and the detecting piezoelectric element 30 b includes electrode layers 31 and 33 and a piezoelectric layer 32. The electrode layer 31 constituting the lower electrode of the driving piezoelectric element 30a and the detecting piezoelectric element 30b is connected to the internal conductor 131 through a contact hole 20h formed in the first insulating layer 20. The electrode layer 33 constituting the upper electrode of the driving piezoelectric element 30a and the detecting piezoelectric element 30b is connected to the surface conductive layer 50 through a contact hole 40h formed in the second insulating layer 40. The driving piezoelectric element 30a and the detecting piezoelectric element 30b are assigned to almost the entire width of the beam F (the length perpendicular to the side connecting the free end and the fixed end).

  The driving piezoelectric element 30a is formed across the boundary between the beam F and the support portion S. The driving piezoelectric element 30a is a driving means for vibrating the weight portion M. A sinusoidal signal that vibrates (circulates) the weight M is applied to the driving piezoelectric element 30a.

  The detecting piezoelectric element 30b is formed across the boundary between the beam F and the weight portion M. The detecting piezoelectric element 30b is a detecting means for detecting the deformation of the beam F accompanying the movement of the weight portion M. Stress and strain associated with the deformation of the beam F are concentrated at the boundary between the weight portion M that behaves substantially as a rigid body and the beam F having flexibility. For this reason, by providing the detection piezoelectric element 30b across the boundary between the weight part M and the beam F, it is possible to efficiently detect the strain accompanying the deformation of the beam F. From the detection piezoelectric element 30b, a signal corresponding to the three-axis angular velocity components can be obtained by synchronous detection or the like.

  The driving piezoelectric element 30a may be provided across the boundaries between the weight M and the four beams F. Further, the detection piezoelectric element 30b may be provided across the boundaries between the support portion S and the four beams F. In any case, it is desirable to provide the driving piezoelectric element 30a and the detecting piezoelectric element 30b in the vicinity of the boundary (vibration end) between the beam F and a substantially rigid body coupled thereto.

  A plurality of internal conductors 131 that are separated (insulated) from each other are formed in the semiconductor layer 13. The internal conductor 131 is made of an impurity diffusion region formed in the semiconductor layer 13. In the plurality of impurity diffusion regions separated from each other, the semiconductor layer 13 has a property as a conductor. Outside the impurity diffusion region, the semiconductor layer 13 has a property as an insulator. Since the semiconductor layer 13 and the electrode layer 31 are separated (insulated) via the first insulating layer 20, a plurality of internal conductors 131 that are separated from each other and insulated can be formed in the semiconductor layer 13. . A part of the internal conductor 131 is used as a conductor of the electrode layer 31 as an upper electrode of the piezoelectric elements 30a and 30b. The remaining part of the internal conductor 131 is used as a conductor of the electrode layer 33 as the upper electrode of the piezoelectric elements 30a and 30b. By forming the internal conducting wire 131 in the semiconductor layer 13, it is possible to wire directly below the piezoelectric elements 30a and 30b. That is, by forming the internal conductor 131 in the semiconductor layer 13, it is not necessary to allocate elements other than the driving piezoelectric element 30 a and the detecting piezoelectric element 30 b to the surface of the beam F in the width direction of the beam F. Therefore, if the margin for the photolithography alignment accuracy is set to 0, the driving piezoelectric element 30a and the detecting piezoelectric element 30b can be assigned to the entire width of the beam F.

  Since the first insulating layer 20 is formed between the semiconductor layer 13 in which the internal conductor 131 is formed and the piezoelectric elements 30a and 30b, the piezoelectric elements 30a and 30a are connected via the contact holes 20h of the first insulating layer 20. It is possible to connect the electrode 30b to the internal conductor 131 of another system insulated from each other.

  A part of the plurality of contact holes 20h of the first insulating layer 20 is formed directly below the electrode layer 31 as the lower electrode of the piezoelectric elements 30a and 30b. The electrode layer 31 is directly connected to the internal conductor 131 through the contact hole 20 h of the first insulating layer 20 formed immediately below the electrode layer 31.

  The other part of the plurality of contact holes 20h of the first insulating layer 20 is in the vicinity of the piezoelectric elements 30a and 30b and is located closer to the fixed end of the beam F than the piezoelectric elements 30a and 30b. The internal conductor 131 whose end is exposed from the contact hole 20h in the vicinity of the piezoelectric elements 30a and 30b is connected to an electrode layer 33 as an upper electrode of the piezoelectric elements 30a and 30b through a surface conductor 50b as a connecting means. ing.

  A second insulating layer 40 is sandwiched between the surface conductor 50b formed of the surface conductor layer 50 and the piezoelectric elements 30a and 30b. That is, the second insulating layer 40 is used as an interlayer insulating film that insulates the electrode layer 31 of the piezoelectric elements 30a and 30b from the surface conductive wire 50b. One end of the surface conducting wire 50 b is directly connected to the electrode layer 33 through a contact hole 40 h formed in the second insulating layer 40. The other end of the surface conducting wire 50b is directly connected to the internal conducting wire 131 through the contact hole 40h in the second insulating layer 40 and the contact hole 20h in the first insulating layer 20.

  The surface conductor layer 50 forms a plurality of bonding pads 50a in the vicinity of the outer periphery of the sensor die 1A. Each bonding pad 50a is directly connected to another internal conductor 131 which is insulated from each other through a contact hole 20h in the first insulating layer 20. That is, each electrode of the plurality of piezoelectric elements 30a and 30b is connected to a different bonding pad 50a through the surface conducting wire 50b and the internal conducting wire 131, respectively. As described above, since the internal conductor 131 connecting the electrodes of the piezoelectric elements 30a and 30b and the bonding pad 50a can be disposed directly below the piezoelectric elements 30a and 30b, the piezoelectric elements 30a and 30b are attached to the beam F. On the other hand, it can be designed as large as possible. In addition, by arranging the conductors of the piezoelectric elements 30a and 30b inside the beam F immediately below the piezoelectric elements 30a and 30b, the second insulating layer 40 is provided to dispose the surface conductor 50b on the piezoelectric elements 30a and 30b. There is no need to form a wide area. That is, by minimizing the region where the second insulating layer 40 is formed, warping of the beam F due to thermal stress of the second insulating layer 40 can be suppressed.

  The package 1B shown in FIG. 2 includes a lidless box type package base 90 and a cover 94 that closes the internal space of the package base 90. The package base 90 and the cover 94 are joined via an adhesive layer 93. The package base 90 is provided with a plurality of through electrodes 91. One end of the wire 95 is bonded to the bonding pad 50a of the sensor die 1A, and the other end is bonded to the through electrode 91 of the package 1B. The bottom surface of the support portion S of the sensor die 1 </ b> A is bonded to the bottom surface 90 a inside the package base 90 with an adhesive layer 92. The height of the gap between the weight portion M of the sensor die 1A and the bottom surface 90a on the inner side of the package base 90 is set by the depth of the recess formed in the bottom surface 90a and the thickness of the adhesive layer 92. Note that an LSI die connected to the sensor die 1A may be accommodated in the package 1B.

(Production method)
Hereinafter, an example of a method for manufacturing the vibrating gyroscope 1 will be described with reference to FIGS. 3 to 11 are all cross-sectional views corresponding to the line AA shown in FIG. 1C except for FIGS. 6C, 7, 10B and 11B. 6C, FIG. 7, FIG. 10B, and FIG. 11B are cross-sectional views corresponding to the line BB shown in FIG. 1C.

First, as shown in FIG. 3, an SOI wafer 10 to be a base layer 11, an etching stopper layer 12, and a semiconductor layer 13 is prepared. The base layer 11 of the SOI wafer 10 is made of single crystal silicon having a thickness of 625 μm. The etching stopper layer 12 of the SOI wafer 10 is made of silicon dioxide having a thickness of 1 μm. The semiconductor layer 13 of the SOI wafer 10 is made of single crystal silicon having a thickness of 10 μm. An etching stopper layer 12 made of silicon oxide is formed on the surface of the single crystal silicon wafer to be the base layer 11 by thermal oxidation, CVD (Chemical Vapor Deposition), etc., and polycrystalline on the surface of the etching stopper layer 12 by CVD or the like. A semiconductor layer 13 made of silicon may be formed. Next, the first insulating layer 20 is formed on the surface of the semiconductor layer 13. As the first insulating layer 20, a silicon dioxide film having a thickness of 0.5 μm is formed by, for example, thermal oxidation or CVD. Then, the internal conductor 131 is formed by introducing impurities into the semiconductor layer 13 of the SOI wafer 10 using the protective film R1 made of photoresist. As impurities, for example, boron (B) ions at a concentration of 2 × 10 ²⁰ / cm ³ are implanted into the surface layer of the semiconductor layer 13 through the first insulating layer 20 with an acceleration voltage of 25 keV. The internal conducting wire 131 is formed, for example, within a depth of 1 μm from the interface between the semiconductor layer 13 and the first insulating layer 20. After ion implantation, activation by annealing is performed. Note that the first insulating layer 20 may be formed after the introduction of impurities into the semiconductor layer 13. FIG. 3B is a plan view showing a pattern of the internal conductor 131.

Next, as shown in FIG. 4, a plurality of contact holes 20 h are formed in the first insulating layer 20 using the protective film R <b> 2 made of photoresist, and the end portions of the internal conductor 131 are exposed from the first insulating layer 20. The contact hole 20h is formed by anisotropically etching the first insulating layer 20 by reactive ion etching using, for example, CF ₄ + H ₂ or CHF ₃ gas. The contact hole 20h may be formed by wet etching using hydrofluoric acid (HF) or buffered hydrofluoric acid (BHF).

Next, as shown in FIG. 5, an electrode layer 31 as a lower electrode layer is laminated on the entire surface of the first insulating layer 20, and a piezoelectric layer 32 is laminated on the entire surface of the electrode layer 31. An electrode layer 33 as an upper electrode layer is laminated on the substrate. At this time, the electrode layer 31 and the internal conductor 131 are connected. As the electrode layers 31 and 33, films made of platinum are formed by sputtering or the like. Titanium (Ti) with a thickness of 30 nm may be deposited as an adhesion layer of platinum silicon oxide. The material of the electrode layer 31 may be iridium oxide (IrO ₂ ). As a material of the electrode layer 33, iridium, iridium oxide, gold (Au), or the like may be used. As the piezoelectric layer 32, a film made of PZT is formed by a sol-gel method, a hydrothermal synthesis method, or the like. Titanium having a thickness of 30 nm may be formed as an adhesion layer of platinum and PZT.

Next, as shown in FIG. 6, the electrode layers 31 and 33 and the piezoelectric layer 32 are etched using a protective film R3 made of a photoresist, so that the piezoelectric element 30a made of the electrode layers 31 and 33 and the piezoelectric layer 32 is obtained. , 30b. At this time, all the piezoelectric elements 30 a and 30 b are formed immediately above the internal conductor 131. At this time, the contact hole 20h for connecting the electrode layer 33 serving as the upper electrode and the internal conductor 131 is exposed. Specifically, the electrode layers 31 and 33 made of platinum are patterned by ion milling using argon (Ar) ions. The piezoelectric layer 32 made of PZT is patterned by reactive ion etching using chlorine (Cl ₂ ) as an etching gas. When the electrode layer 31 filling the contact hole 20h for connecting the electrode layer 33 and the internal conductor 131 is completely removed by ion milling, the surface layer of the semiconductor layer 13 needs to be slightly over-etched. The depth _{h e} of the semiconductor layer 13 which is over-etching is sufficiently shallow for example 100nm than the depth _{h 131} of the inner conductor 131 (1 [mu] m).

Next, as shown in FIG. 7, the first insulating layer 20 and the semiconductor layer 13 are patterned into a predetermined shape using a protective film R4 made of a photoresist. As a result, a pattern of four beams F is formed. The first insulating layer 20 is patterned by reactive ion etching using CHF ₃ gas or CF ₄ + H ₂ gas. The semiconductor layer 13 is patterned by reactive ion etching using CF ₄ + O ₂ gas. The pattern of the beam F may be formed by wet etching using hydrofluoric acid or buffered hydrofluoric acid.

  Next, as shown in FIG. 8, a second insulating layer 40 having a predetermined pattern having contact holes 40h on the surfaces of the piezoelectric elements 30a and 30b and the first insulating layer 20 is formed. For example, a photosensitive polyimide having a thickness of 5 μm is applied to the entire surface of the piezoelectric elements 30a and 30b and the first insulating layer 20, and patterned into a predetermined shape by exposure and development, thereby forming the second insulating layer 40 having the contact hole 40h. To do. The pattern of the second insulating layer 40 is divided into a plurality of regions to be a plurality of interlayer insulating films. Each region of the second insulating layer 40 that is separated from each other has two contact holes 40h that expose the electrode layer 33 as an upper electrode and the contact holes 20h located outside the piezoelectric elements 30a and 30b.

Next, as shown in FIG. 9, the surface conductive layer 50 is laminated on the surface of the second insulating layer 40 and the surface conductive layer 50 is etched to connect the piezoelectric layer 32 as the upper electrode and the internal conductive line 131. 50b and bonding pad 50a are formed. As the surface conductive layer 50, an aluminum (Al) film having a thickness of 0.5 μm is formed by sputtering, for example. An aluminum silicon (AlSi) film may be formed as the surface conducting wire layer 50. The pattern of the surface conductive layer 50 is formed by reactive ion etching using, for example, chlorine (Cl ₂ ) gas. A titanium film with a thickness of 30 nm may be formed as an aluminum adhesion layer. The surface conductive layer 50 may be patterned by, for example, an ion milling method or wet etching using a mixed solution of phosphoric acid, nitric acid, and acetic acid instead of reactive ion etching using Cl ₂ gas.

  Next, the surface on which the piezoelectric elements 30a and 30b of the laminated structure W formed by the above-described steps are formed is bonded to the sacrificial substrate 99 as shown in FIG. As the adhesive layer 98, for example, a wax, a photoresist, a double-sided pressure-sensitive adhesive sheet, or the like is used.

Next, the base layer 11 is patterned into a predetermined shape by etching the base layer 11 using the protective film R5 made of a photoresist. Specifically, for example, the base layer 11 is anisotropically processed by Deep-RIE (so-called Bosch process) in which a passivation step using SF ₆ plasma gas and an etching step using C ₄ F ₈ plasma gas are alternately repeated at short time intervals. Etch. Note that the patterning of the base layer 11 may be performed first, or may be performed during the process of processing the surface side of the semiconductor layer 13.

  Next, as shown in FIG. 11, the exposed portion of the etching stopper layer 12 is removed by etching. As a result, the beam F and the weight part M are released. Specifically, the exposed portion of the etching stopper layer 12 is removed by wet etching using buffered hydrofluoric acid. Thereafter, post-processes such as dicing and packaging are performed to complete the vibrating gyroscope 1 shown in FIG.

  According to the method for manufacturing the vibrating gyroscope 1 described above, the internal conductor 131 can be disposed directly below the piezoelectric elements 30a and 30b, so that the piezoelectric elements 30a and 30b can be disposed as wide as possible with respect to the beam F. it can.

2. Second embodiment (Configuration)
FIG. 12 is a sectional view showing a sensor die 2A of a vibrating gyroscope according to a second embodiment of the present invention. The sensor die 2A differs from the sensor die 1A of the first embodiment in the configuration of the piezoelectric elements 30a and 30b and the surface conducting wire 50b, and is otherwise substantially the same as the first embodiment. 12A is a cross-sectional view corresponding to the line AA shown in FIG. 1C. 12B is a cross-sectional view corresponding to the line BB shown in FIG. 1C. In FIG. 12A and FIG. 12B, the interface of the layer which comprises the sensor die 2A is shown with the broken line, and the boundary of the mechanical component which comprises the sensor die 2A is shown with the continuous line.

  As shown in FIG. 12, the pattern of the piezoelectric layer 32 may be designed wider than the pattern of the electrode layer 31 as the lower electrode, and the piezoelectric layer 32 may be in contact with the first insulating layer 20 around the electrode layer 31. good. By completely covering the electrode layer 31 with the piezoelectric layer 32, it is possible to reliably prevent the electrode layer 31 and the electrode layer 33 from being directly short-circuited or leaked.

(Production method)
13 and 14 are cross-sectional views showing a method for manufacturing the sensor die 2A, and correspond to the cross section taken along the line AA shown in FIG. 1C. When forming the piezoelectric elements 30a and 30b, two types of protective films R31 and R32 are used as shown in FIGS. 13 and 14 in order to form the pattern of the electrode layer 31 and the pattern of the electrode layer 33 separately.

  That is, after the electrode layer 31 is formed on the entire surface of the first insulating layer 20, the electrode layer 31 is patterned into a predetermined shape by etching using a protective film R31 made of a photoresist as shown in FIG. At this time, the protective film R31 may be formed so that the electrode layer 31 remains inside the contact hole 20h of the first insulating layer 20.

Next, the piezoelectric layer 32 and the electrode layer 33 are sequentially laminated on the entire surfaces of the first insulating layer 20 and the electrode layer 31, and the piezoelectric layer 32 and the electrode layer 33 are formed into a predetermined shape by etching using a protective film R32 made of photoresist. To pattern. At this time, the pattern of the piezoelectric layer 32 is formed wider than the pattern of the electrode layer 31 so that the piezoelectric layer 32 completely covers the electrode layer 31. Then, the pattern of the electrode layer 33 is matched with the pattern of the piezoelectric layer 32. Note that the pattern of the electrode layer 33 may match the pattern of the electrode layer 31. Also at this time, the protective film R32 may be formed so that the electrode layer 31 remains inside the contact hole 20h of the first insulating layer 20.
Thereafter, when the surface conductor 50b and the like are formed as in the first embodiment, the sensor die 2A is completed.

3. Third Embodiment FIG. 15 is a cross-sectional view showing a sensor die 3A of a vibrating gyroscope according to a third embodiment of the present invention. The sensor die 3A differs from the sensor die 1A of the first embodiment in the configuration of the piezoelectric elements 30a, 30b and the surface conducting wire 50b, and is otherwise substantially the same as the first embodiment. FIG. 15A is a cross-sectional view corresponding to the line AA shown in FIG. 1C. FIG. 15B is a cross-sectional view corresponding to the line BB shown in FIG. 1C. In FIG. 15A and FIG. 15B, the interface of the layer which comprises the sensor die 3A is shown with the broken line, and the boundary of the mechanical component which comprises the sensor die 3A is shown with the continuous line.

  As shown in FIG. 15, the pattern of the electrode layer 33 as the upper electrode is designed to be narrower than the pattern of the electrode layer 31 as the lower electrode, and the electrode layer 31 or the piezoelectric layer 32 is exposed from the periphery of the electrode layer 33. You may do it. If the pattern of the electrode layer 33 as the upper electrode is designed to be narrower than the pattern of the electrode layer 31, a short circuit between the electrode layer 31 and the electrode layer 33 can be prevented. Furthermore, it is preferable to arrange the pattern of the electrode layer 33 inside the pattern of the piezoelectric layer 32. In this case, in order to simplify the patterning process, it is more preferable to match the patterns of the electrode layer 31 and the piezoelectric layer 32.

(Production method)
16 and 17 are cross-sectional views showing a method for manufacturing the sensor die 3A, and correspond to the cross section taken along the line BB shown in FIG. 1C. When the piezoelectric elements 30a and 30b are formed, two types of protective films R33 and R34 are used as shown in FIGS. 16 and 17 in order to form the pattern of the electrode layer 31 and the pattern of the electrode layer 33 separately.

  That is, after the electrode layers 31 and 33 and the piezoelectric layer 32 are formed on the entire surface of the first insulating layer 20 as in the first embodiment, etching is performed using a protective film R33 made of photoresist as shown in FIG. The electrode layer 33 and the piezoelectric layer 32 are patterned into a predetermined shape. At this time, the etching end point may be set so that the piezoelectric layer 32 remains even in the region not covered by the protective film R33 in the etching of the piezoelectric layer 32.

Next, as shown in FIG. 17, the electrode layer 31 is patterned into a predetermined shape by etching using a protective film R34 made of a photoresist. At this time, the pattern of the electrode layer 31 is formed wider than the pattern of the electrode layer 33 so that the electrode layer 31 protrudes around the electrode layer 33.
When the patterns of the piezoelectric layer 32 and the electrode layer 31 are matched, only the electrode layer 33 is etched in the patterning using the protective film R33, and the piezoelectric layer 32 and the electrode layer 31 are etched by etching using the protective film R34. May be patterned.
Thereafter, when the surface conductive wire 50b and the like are formed as in the first embodiment, the sensor die 3A is completed.

4). Fourth Embodiment FIG. 18 is a cross-sectional view showing a sensor die 4A of a vibrating gyroscope according to a third embodiment of the present invention. The sensor die 4A differs from the sensor die 1A of the first embodiment in the configuration of the piezoelectric elements 30a, 30b and the surface conducting wire 50b, and is otherwise substantially the same as the first embodiment. 18A is a cross-sectional view corresponding to the line AA shown in FIG. 1C. 18B is a cross-sectional view corresponding to the line BB shown in FIG. 1C. In FIG. 18A and FIG. 18B, the interface of the layers constituting the sensor die 4A is indicated by a broken line, and the boundary of the mechanical components constituting the sensor die 4A is indicated by a solid line.

  As shown in FIG. 18A, the pattern of the piezoelectric layer 32 is designed wider than the pattern of the electrode layer 31 as the lower electrode, and the lower surface constituting the interface with the electrode layer 31 of the piezoelectric layer 32 forms the interface with the electrode layer 33. The side surface of the piezoelectric layer 32 (the end surface between the upper surface and the lower surface) may be inclined so as to be wider than the upper surface, and the piezoelectric layer 32 may be in contact with the first insulating layer 20 around the electrode layer 31. good. As a result, the piezoelectric layer 32 itself functions as an interlayer insulating film between the surface conducting wire 50b and the electrode layer 31 as the lower electrode, so that the second insulating layer 40 becomes useless. The piezoelectric layer 32 that completely covers the electrode layer 31 serving as the lower electrode can reliably prevent a short circuit and a leak between the electrode layer 31 serving as the lower electrode and the surface conductor 50b. In addition, by completely covering the electrode layer 31 as the lower electrode with the piezoelectric layer 32, it is possible to reliably prevent the electrode layer 31 and the electrode layer 33 from being directly short-circuited or leaked.

  In addition, you may form the convex curve which inclined the side surface of the electrode layer 33 and the piezoelectric layer 32, the inclined concave curve, or its cross section in S shape. Further, the electrode layer 33 is stretched on the side surface of the piezoelectric layer 32, and the electrode layer 33 and the internal conductor 131 are directly connected, or the electrode layer 31 and the electrode layer 33 in the contact hole 20h of the first insulating layer 20 are directly connected. You can also In this case, the electrode layer 33 itself functions as a connection means. In this case, the surface conductive layer 50 can be omitted by forming the bonding pad 50 a with the electrode layer 33.

(Production method)
19 to 22 are sectional views showing a method for manufacturing the sensor die 4A, and correspond to the section taken along the line AA shown in FIG. 1C. When the piezoelectric elements 30a and 30b are formed, two types of protective films R35 and R36 are used as shown in FIGS. 19 and 20 in order to form the pattern of the electrode layer 31 and the pattern of the electrode layer 33 separately.

  That is, after the electrode layer 31 is formed on the entire surface of the first insulating layer 20 as in the second embodiment, the electrode layer 31 is formed into a predetermined shape by etching using a protective film R35 made of photoresist as shown in FIG. To pattern. At this time, the protective film R35 may be formed so that the electrode layer 31 remains inside the contact hole 20h of the first insulating layer 20.

  Next, the piezoelectric layer 32 and the electrode layer 33 are sequentially laminated on the entire surface of the first insulating layer 20 and the electrode layer 31, and a protective film R 36 whose side surface is an inclined surface is formed on the surface of the electrode layer 33. Specifically, a positive photoresist is applied to the entire surface of the electrode layer 33, and the photoresist is exposed and developed using a mask. Thereafter, when the photoresist is baked on a hot plate at 130 ° C. for 3 minutes, a protective film R36 whose side surface is inclined is formed. The protective film R36 whose side surface is inclined as described above can also be formed using a multi-tone mask (halftone mask or graytone mask).

  Next, the electrode layer 33 and the piezoelectric layer 32 are anisotropically etched together with the protective film R36 whose side surface is inclined. Specifically, for example, the electrode layer 33 and the piezoelectric layer 32 are etched together with the protective film R36 by a milling method using argon ions. At this time, if the selection ratio of the electrode layer 33 and the piezoelectric layer 32 to the protective film R36 is set to 1: 1, the side surface of the protective film R36 can be directly transferred to the side surface of the electrode layer 33 and the piezoelectric layer 32. If the selection ratio of the electrode layer 33 and the piezoelectric layer 32 to the protective film R36 is not 1: 1, the side surfaces of the electrode layer 33 and the piezoelectric layer 32 having an inclination angle different from the inclination angle of the side surface of the protective film R36 are formed.

  Thus, by forming the side surfaces of the electrode layer 33 and the piezoelectric layer 32 as inclined surfaces, the surface conductive layer 50 is formed when the surface conductive layer 50 is formed as shown in FIG. The step coverage is improved. The second insulating layer 40 in the second embodiment exhibits the function of relaxing the step on the base surface of the surface conductive layer 50, but the side surfaces of the electrode layer 33 and the piezoelectric layer 32 are inclined as in the present embodiment. Therefore, it is not necessary to form the second insulating layer 40 in order to improve the step coverage of the surface conductive layer 50.

5). Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, the electrode layer 33 as the upper electrode and the bonding pad 50a may be connected via two or more internal wirings 131 and two or more surface conductive wires 50b. When the surface conductive wire 50b that connects the two internal wirings 131 is formed in a region where the piezoelectric elements 30a and 30b do not need to be disposed (for example, the central portion of the beam F), the path length of the internal wiring 131 can be shortened. Wiring resistance is reduced. In addition to the vibration gyroscope, the present invention can also be applied to other MEMS sensors such as an acceleration sensor, a motion sensor that detects angular velocity and acceleration, and a microphone. The present invention can also be applied to MEMS actuators that use piezoelectric elements as drive means. Further, the present invention can also be applied to MEMS using a diaphragm as the flexible portion.

  Further, for example, the materials, dimensions, film formation methods, and pattern transfer methods shown in the above embodiment are merely examples, and descriptions of addition and deletion of processes and replacement of process orders that are obvious to those skilled in the art are omitted. Has been. Also, for example, in the above-described manufacturing process, the film composition, film forming method, film contour forming method, process sequence, etc. are appropriately selected according to the combination of film materials, film thickness, required contour shape accuracy, etc. There is no particular limitation.

FIG. 1A is a cross-sectional view according to the first embodiment of the present invention. FIG. 1B is a cross-sectional view according to the first embodiment of the present invention. FIG. 1C is a top view according to the first embodiment of the present invention. Sectional drawing concerning 1st embodiment of this invention. FIG. 3A is a sectional view according to the first embodiment of the present invention. FIG. 3B is a plan view according to the first embodiment of the present invention. Sectional drawing concerning 1st embodiment of this invention. Sectional drawing concerning 1st embodiment of this invention. FIG. 6A is a sectional view according to the first embodiment of the present invention. 6B is a partially enlarged view of FIG. 6A. FIG. 6C is a cross-sectional view according to the first embodiment of the present invention. Sectional drawing concerning 1st embodiment of this invention. Sectional drawing concerning 1st embodiment of this invention. Sectional drawing concerning 1st embodiment of this invention. FIG. 10A is a sectional view according to the first embodiment of the present invention. FIG. 10B is a cross-sectional view according to the first embodiment of the present invention. FIG. 11A is a sectional view according to the first embodiment of the present invention. FIG. 11B is a cross-sectional view according to the first embodiment of the present invention. FIG. 12A is a sectional view according to the second embodiment of the present invention. FIG. 12B is a sectional view according to the second embodiment of the present invention. Sectional drawing concerning 2nd embodiment of this invention. FIG. 14A is a sectional view according to the second embodiment of the present invention. 14B is a partially enlarged view of FIG. 14A. FIG. 15A is a sectional view according to a third embodiment of the present invention. FIG. 15B is a sectional view according to the third embodiment of the present invention. Sectional drawing concerning 3rd embodiment of this invention. FIG. 17A is a cross-sectional view according to a third embodiment of the present invention. FIG. 17B is a partially enlarged view of FIG. 17A. FIG. 18A is a cross-sectional view according to a fourth embodiment of the present invention. FIG. 18B is a sectional view according to the fourth embodiment of the present invention. Sectional drawing concerning 4th embodiment of this invention. Sectional drawing concerning 4th embodiment of this invention. Sectional drawing concerning 4th embodiment of this invention. FIG. 22A is a sectional view according to a fourth embodiment of the present invention. 22B is a partially enlarged view of FIG. 22A.

Explanation of symbols

1: vibrating gyroscope, 1A: sensor die, 1B: package, 2A: sensor die, 3A: sensor die, 4A: sensor die, 10: SOI wafer, 11: base layer, 12: etching stopper layer, 13: semiconductor layer, 20: first One insulating layer, 20h: contact hole, 30a: driving piezoelectric element, 30b: detecting piezoelectric element, 31: electrode layer, 32: piezoelectric layer, 33: electrode layer, 40: second insulating layer, 40h: contact hole, 50: Surface conductor layer, 50a: Bonding pad, 50b: Surface conductor, 90: Package base, 90a: Bottom surface, 91: Through electrode, 92: Adhesive layer, 93: Adhesive layer, 94: Cover, 95: Wire, 98: Adhesive layer, 99: sacrificial substrate, 131: internal conductor, F: beam, M: weight, R1: protective film, R2: protective film, R3: protective film, R31: protective Film, R32: protective film, R33: protective film, R34: protective film, R35: protective film, R36: protective film, R4: protective film, R5: protective film, S: supporting unit, W: laminated structure

Claims (6)

A flexible portion having a flexibility including an insulating layer in which a plurality of contact holes are formed and a semiconductor layer in contact with the insulating layer;
A plurality of conductive wires made of a plurality of impurity diffusion regions formed in the semiconductor layer and separated from each other;
A lower electrode layer stacked on the surface of the insulating layer and in contact with the conductor through the contact hole; a piezoelectric layer stacked on the surface of the lower electrode layer; and an upper electrode layer stacked on the surface of the piezoelectric layer. A piezoelectric element located on the flexible part;
A connection means comprising a conductive layer for connecting the upper electrode layer and the conductive wire through the contact hole formed in the flexible portion;
A MEMS comprising: The pattern of the piezoelectric layer is wider than the pattern of the lower electrode layer and is in contact with the insulating layer around the lower electrode layer.
The MEMS according to claim 1. In the piezoelectric layer, a lower surface constituting an interface with the lower electrode layer and the insulating layer is wider than an upper surface constituting an interface with the upper electrode layer, and a side surface between the lower surface and the upper surface is an inclined surface,
The connecting means is laminated on the side surface of the piezoelectric layer,
The MEMS according to claim 2. The pattern of the upper electrode layer is narrower than the pattern of the lower electrode layer,
The lower electrode layer or the piezoelectric layer is exposed from the periphery of the upper electrode layer,
The MEMS according to claim 1. A weight part;
A support part;
A vibrating gyroscope that is a MEMS according to any one of claims 1 to 4, further comprising:
The flexible portion comprises a beam having a free end coupled to the weight portion and a fixed end coupled to the support portion;
The piezoelectric element constitutes a driving piezoelectric element that drives the weight part by distorting the flexible part, and a detection piezoelectric element that detects distortion of the flexible part accompanying the movement of the weight part. ,
Vibrating gyroscope. A plurality of contact holes are formed in the insulating layer stacked on the surface of the semiconductor layer,
Forming a flexible portion including the insulating layer and the semiconductor layer and having flexibility;
Forming a plurality of conductive wires composed of a plurality of impurity diffusion regions exposed from the plurality of contact holes in the semiconductor layer;
And including a lower electrode layer stacked on the surface of the insulating layer and in contact with the conductor through the contact hole, a piezoelectric layer stacked on the surface of the lower electrode layer, and an upper electrode layer stacked on the surface of the piezoelectric layer. Forming a piezoelectric element located on the flexure,
Forming a conductive wire layer connecting the upper electrode layer and the conductive wire through the contact hole;
The manufacturing method of MEMS including this.

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