JP2010091351A - Method of manufacturing mems sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance detection accuracy of a physical quantity by a MEMS sensor. <P>SOLUTION: A method of manufacturing the MEMS sensor including a support part, a beam part having one end coupled to the support part and thinner than the support part, a weight part coupled to the other end of the beam part and thicker than the beam part, and a strain detection means provided at the beam part and detecting the strain of the beam part includes the steps of: forming a laminate structure including the strain detection means including films made by laminating the films on a surface of a substrate and the substrate; forming a first protective film having a first through-hole formed therein and a second protective film having a second through-hole formed therein on the back surface of the substrate; etching the laminate structure exposed from the first through-hole so that the laminate structure is penetrated, thereby forming a side surface of the beam part and a part of a side surface of the weight part separated from the beam part; and etching the substrate exposed from the second through-hole, thereby adjusting the thickness of the beam part and forming the residual part of the side surface of the weight part made of the substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a MEMS (Micro Electro Mechanical Systems) sensor.

2. Description of the Related Art Conventionally, MEMS sensors that detect acceleration, posture (inclination angle), angular velocity, vibration, and the like by detecting deformation of a beam portion caused by an inertial force acting on a weight portion with a piezoresistive element or the like are known. In such a MEMS sensor, since the force acting on the beam portion from the weight portion deforms the beam portion according to the force acting on the weight portion, the detection accuracy of physical quantities such as acceleration, posture (tilt angle), angular velocity, amplitude, etc. Depends on the alignment accuracy between the weight portion and the beam portion.
Patent Documents 1 and 2 describe a method of manufacturing a MEMS sensor in which a weight portion and a beam portion are formed by etching from both front and back sides of a substrate.
Patent Document 3 describes a method of manufacturing a MEMS sensor in which a beam part and a weight part are formed by welding a low melting point metal body to the beam part.
JP 2007-61956 A Japanese Patent Laying-Open No. 2005-61840 Japanese Patent Laid-Open No. 9-80070

  However, in the manufacturing methods described in Patent Documents 1 and 2, since the shapes of the weight portion and the beam portion are formed by etching from both the front and back sides of the substrate, the position of the protective film used when etching from both the front and back sides is formed. The positions of the weight part and the beam part shift due to the deviation. Moreover, in the manufacturing method described in Patent Document 3, the accuracy of mechanically aligning the low melting point metal body with the beam portion is a problem, and it is difficult to increase the alignment accuracy of the weight portion and the beam portion. , Manufacturing costs increase due to mechanical sequential processing.

  The present invention was created in view of these problems, and an object of the present invention is to improve the detection accuracy of a physical quantity by a MEMS sensor.

  (1) A MEMS sensor manufacturing method for achieving the above object includes a support part, a beam part having one end coupled to the support part and thinner than the support part, and a beam part coupled to the other end of the beam part and thicker than the beam part. A method for manufacturing a MEMS sensor, comprising: a weight portion; and a strain detection means provided on the beam portion for detecting strain of the beam portion, wherein the strain detection is configured by a film by laminating a film on the surface of the substrate. A first protective film having a first through hole and a second protective film having a second through hole are formed on the back surface of the substrate. And forming a side surface of the beam portion and a portion spaced apart from the beam portion of the side surface of the weight portion by etching until the laminated structure exposed from the first through hole is penetrated. Adjust the thickness of the beam by etching the substrate exposed through the second through hole And forming the remainder consisting of the substrate side of the weight portion includes.

  According to the present invention, the entire side surface of the beam portion and the entire side surface of the weight portion are formed by etching using the protective film on the back surface that is one of the two main surfaces of the substrate. The alignment accuracy can be increased. Therefore, according to the present invention, the physical quantity detection accuracy by the MEMS sensor can be increased. Note that the side surface of the beam portion and the side surface of the weight portion are surfaces perpendicular to the main surface of the substrate.

(2) In the MEMS sensor manufacturing method for achieving the above object, a single-layer first protective film having a thin part and a thick part thicker than the thin part is formed on the back surface of the substrate,
After etching until the laminated structure exposed from the first through-hole is penetrated, the entire surface of the first protective film is etched until the thin-walled portion disappears, thereby forming the first protective film comprising the remaining portion of the first protective film. Forming a second protective film may be included.

According to the present invention, since the single-layer first protective film is transformed into the second protective film, the step of adding the material of the second protective film becomes unnecessary.
(3) In the MEMS sensor manufacturing method for achieving the above object, a photosensitive resin film is formed on the back surface of the substrate, the photosensitive resin film is exposed through a multi-tone mask, and the exposed photosensitive resin film is exposed. And developing a thin-walled portion and a thick-walled portion.
According to the present invention, since the exposure process for forming the first protective film and the second protective film is performed only once, the alignment accuracy between the weight part and the beam part can be further increased. For this reason, according to this invention, the detection accuracy of the physical quantity by a MEMS sensor can further be improved.

(4) In the MEMS sensor manufacturing method for achieving the above object, the entire surface of the first protective film is anisotropically etched to form a portion separated from the beam portion on the side surface of the weight portion. Forming a second protective film including an edge of the thick part of the first protective film may be included.
According to the present invention, the planar shape of the thick portion of the first protective film can be directly changed to the planar shape of the second protective film. In addition, in order to leave the edge of the thick part of the first protective film that forms the part separated from the beam part on the side surface of the weight part in the second protective film, the side surface of the beam part and the beam on the side surface of the weight part The part separated from the part is determined by the pattern of the thick part. Therefore, according to the present invention, the alignment accuracy between the weight portion and the beam portion can be further increased.
(5) In the MEMS sensor manufacturing method for achieving the above object, a single layer first protective film having a uniform thickness is formed on the back surface of the substrate and is exposed from the first through-hole. After the structure is etched, the first protective film includes an edge of the first protective film formed by removing a part of the first protective film by laser ablation to form a part separated from the beam part on the side surface of the weight part. Forming a second protective film composed of the remainder of the protective film.
According to the present invention, since the single-layer first protective film is transformed into the second protective film, the step of adding the material of the second protective film becomes unnecessary. In addition, in order to leave the edge of the first protective film forming a part of the side surface of the weight part in the second protective film, the part of the side of the beam part and the side of the weight part spaced apart from the beam part is the first This is determined by the pattern of the protective film. Therefore, according to the present invention, the alignment accuracy between the weight portion and the beam portion can be further increased.
(6) In the MEMS sensor manufacturing method for achieving the above object, a first protective film comprising a lower layer portion serving as a second protective film and an upper layer portion made of a material that can be etched leaving the lower layer portion as a substrate. After etching the laminated structure that is formed on the entire back surface and exposed from the first through hole, the lower layer is exposed by removing the upper layer by etching, and a part of the lower layer is removed by laser ablation This may include forming a second protective film made up of the remainder of the lower layer part including the edge of the lower layer part in which the part separated from the beam part on the side surface of the weight part is formed.
According to the present invention, in order to leave the edge of the lower layer portion of the first protective film in which the portion separated from the beam portion on the side surface of the weight portion is left in the second protective film, the side surface of the beam portion and the weight portion The part spaced apart from the side beam part is determined by the pattern of the first protective film. Therefore, according to the present invention, the alignment accuracy between the weight portion and the beam portion can be further increased.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, 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)
FIG. 1 shows a piezoresistive acceleration sensor which is a MEMS sensor manufactured according to the first embodiment of the present invention. The acceleration sensor 1 is a MEMS sensor for detecting three-axis acceleration components orthogonal to each other.

  The acceleration sensor 1 includes a support portion S having a rectangular frame shape, cantilevered beam portions F1, F2, F3, and F4 having one end coupled to the support portion S, and beam portions F1, F2, F3, and F4. And a piezoresistive element 40 as strain detecting means, which are accommodated in a package (not shown). These structural elements and electrical functional elements constituting the acceleration sensor 1 include a laminated structure in which a substrate 100 made of a plate-like bulk material, a silicon layer 104, an insulating layer 106, and a wiring layer 108 are integrally joined. It is composed by the body.

  The support portion S is a structural element for supporting the beam portions F1, F2, F3, and F4. The form of the support part S is designed according to the form and arrangement of the beam parts F1, F2, F3, F4 and the form and arrangement of the weight part M. The support part S includes a substrate 100, a silicon layer 104, and an insulating layer 106. The support portion S is a multilayer structure including a substrate 100 that is sufficiently thicker than the beam portions F1, F2, F3, and F4. Therefore, the support portion S is not substantially deformed.

  One end of each of the beam portions F1, F2, F3, and F4 having the same form is coupled to the support portion S. The beam portions F1, F2, F3, and F4 and the support portion S are separated by a slit H1 that is a through hole, and the beam portions F1, F2, F3, and F4 and the weight portion M are separated by a slit H2 that is a through hole. Yes. The beam portions F1 and F2 are arranged in series in parallel with the longitudinal direction of the support portion S and the weight portion M with the weight portion M interposed therebetween. The beam portions F3 and F4 are arranged in series in parallel with the longitudinal direction of the support portion S and the weight portion M with the weight portion M interposed therebetween. The other ends of the beam portions F1 and F3 are coupled to one side surface of the weight portion M, and the other ends of the beam portions F2 and F4 are coupled to the other side surface of the weight portion M. The beam portions F 1, F 2, F 3, and F 4 are composed of the silicon layer 104 and the insulating layer 106.

  The weight portion M has a columnar shape having a cross-shaped bottom surface, and has a form in which the center of gravity is located away from the surface in contact with the beam portions F1, F2, F3, and F4. The weight portion M is long in the longitudinal direction of the beam portions F1, F2, F3, and F4 and short in the short direction of the beam portions F1, F2, F3, and F4. The portion of the side surface of the weight portion M that faces the side surfaces of the beam portions F1, F2, F3, and F4 is parallel to the side surfaces of the beam portions F1, F2, F3, and F4. The weight portion M includes a substrate 100 that is sufficiently thicker than the beam portions F1, F2, F3, and F4. Therefore, the weight part M behaves as a rigid body that moves relative to the support part S.

  A total of twelve piezoresistive elements 40 are provided in the proximity region of the beam portions F1, F2, F3, and F4 to the support portion S and the proximity region of the weight portion M. The piezoresistive element 40 includes a resistance portion 42 having a relatively low impurity concentration and a connection resistance reducing portion 41 having a high impurity concentration. All of these piezoresistive elements 40 straddle the boundary between the beam portions F1, F2, F3, F4 and the support portion S or the boundary between the beam portions F1, F2, F3, F4 and the weight portion M. The piezoresistive element 40 is formed in the silicon layer 104. The direction of the stress generated by the deformation of the beam portions F1, F2, F3, and F4 is reversed between the front surface and the back surface of the beam portions F1, F2, F3, and F4. For this reason, the piezoresistive element 40 is thinly formed near the interface of the silicon layer 104. The piezoresistive elements 40 form a bridge circuit with a set of four, and are wired so that output signals corresponding to three-axis acceleration components orthogonal to each other can be extracted from each bridge circuit. A portion where the line width of the wiring layer 108 constituting a part of the wiring for connecting the piezoresistive element 40 as a bridge circuit is narrowed is omitted in FIG. 1A.

(Production method)
Next, a method for manufacturing the acceleration sensor 1 will be described with reference to FIGS.
First, the laminated structure W shown in FIG. 2 in which a three-dimensional mechanical structure is not formed is formed by a known method in which a thin film is laminated, modified, or etched on the surface of the substrate 100. For example, the surface of a base wafer made of single crystal silicon (Si) having a thickness of 400 to 625 μm is thermally oxidized to form an etch stopper layer 102 made of silicon dioxide (SiO ₂ ) and having a thickness of 1 μm, and the remaining portion is thick. A substrate 100 composed of a silicon layer 101 and an etch stopper layer 102 is formed. Here, the substrate 100 is made of a plate-shaped bulk material that is sufficiently thick with respect to the thin film laminated on the surface of the substrate 100 and has a thickness that almost controls the rigidity of the support portion S and the weight portion M. That's fine. Then, the laminated structure W shown in FIG. 2 is formed by processing performed from the surface side which is one of the two main surfaces of the substrate 100. For example, a bond wafer made of single crystal silicon and forming a thin silicon layer 104 having a thickness of 5 to 20 μm is bonded to the etch stopper layer 102 of the substrate 100 to obtain an SOI (Silicon On Insulator) wafer. Next, impurity ions are implanted from the surface of the thin silicon layer 104 and activated to form the piezoresistive element 40 in the silicon layer 104. Next, as the insulating layer 106, for example, a film of 1 μm thick silicon dioxide, silicon nitride (SiN) or the like is formed on the surface of the silicon layer 104 by a thermal oxidation method or a deposition method. Next, a wiring layer 108 made of aluminum (Al), copper (Cu), AlSi or the like is formed on the surface of the insulating layer 106, and the wiring layer 108 and the piezoresistive element 40 are connected through a contact hole.

  Next, as shown in FIGS. 3A, 3B, and 3C, the laminated structure W is temporarily bonded to the sacrificial substrate 99, and a first protective film R is formed on the back surface of the substrate 100. The sacrificial substrate 99 and the laminated structure W can be temporarily bonded using the bonding means B made of wax, photoresist, double-sided pressure-sensitive adhesive sheet, or the like. The first protective film R is made of a photoresist, which is a photosensitive resin, and has a thin wall for forming the beam portions F1, F2, F3, and F4 thinner than the support portion S and the weight portion M shown in FIG. A portion R2, and a thick portion R1 for forming the support portion S and the weight portion M thicker than the beam portions F1, F2, F3, and F4 are provided. The first protective film R is formed with slits RS which are first through holes for forming the slits H1 and H2 which are the through holes shown in FIG. The thickness of the thick portion R1 is, for example, 10 μm, and the thickness of the thin portion R2 is, for example, 3 μm.

  The first protective film R having such a three-dimensional shape is formed by exposing a photosensitive material through a multi-tone mask (halftone mask or graytone mask) and developing the exposed photosensitive material. It is desirable. Note that the first protective film R having a three-dimensional shape may be formed by a nanoimprint method or a laser direct drawing method.

Next, as shown in FIGS. 4A and 4B, etching is performed until the laminated structure W exposed from the slit RS of the first protective film R is penetrated. As a result, all the side surfaces of the beam portions F1, F2, F3, and F4 shown in FIG. 1 and portions spaced from the beam portions F1, F2, F3, and F4 on the side surface of the weight portion M are formed. At this time, portions parallel to the side surfaces of the beam portions F1, F2, F3, and F4 on the side surface of the weight portion M are formed. Specifically, for example, a thick silicon layer of the substrate 100 is formed by Deep-RIE (Reactive Ion Etching), which is called a Bosch process in which passivation using C ₄ F ₈ plasma and etching using SF ₆ plasma are alternately repeated at short intervals. 101 is etched. Subsequently, the etch stopper layer 102 made of silicon dioxide on the substrate 100 is etched by reactive ion etching (RIE) using CHF ₃ gas. Subsequently, the thin silicon layer 104 made of single crystal silicon is etched by reactive ion etching using CF ₄ gas. Subsequently, the insulating layer 106 made of silicon dioxide is etched by reactive ion etching using CHF ₃ gas.

  Next, as shown in FIGS. 5A and 5B, the entire surface of the first protective film R made of photoresist is etched until the thin-walled portion R2 disappears, thereby forming a second through hole RT. A second protective film R composed of the remaining part of the protective film R is formed. At this time, the pattern of the second protective film R is accurately formed in a self-aligned manner by the pattern of the thick portion R1 of the first protective film R. Specifically, for example, the entire surface of the first protective film R may be anisotropically etched by reactive ion etching using oxygen (O) plasma. Note that the first protective film R may be anisotropically etched by milling with argon (Ar) ions. By anisotropically etching the first protective film R, the outline of the thick portion R1 viewed from the direction perpendicular to the back surface of the substrate 100 is transferred almost directly to the outline of the second protective film R. Can do. Further, by leaving the edge of the thick part R1 of the first protective film R, which forms the part spaced from the beam parts F1, F2, F3, and F4 on the side surface of the weight part M, in the second protective film R The portions spaced from the beam portions F1, F2, F3, and F4 on the side surface of the weight portion M are determined by the pattern of the thick portion R1. Further, the first protective film R may be transformed into the second protective film R by isotropic etching. However, when deforming by isotropic etching, it is necessary to design the outline of the thick portion R1 in anticipation of etching in a direction parallel to the back surface of the substrate 100.

Next, as shown in FIGS. 6A and 6B, the beam portions F1, F2, and F3 shown in FIG. 1 of the substrate 100 are etched by etching the substrate 100 exposed from the second through hole RT of the second protective film R. , F4 is removed. As a result, the thicknesses of the beam portions F1, F2, F3, and F4 shown in FIG. 1 are adjusted, and the remaining portion Ms made of the substrate 100 on the side surface of the weight portion M is formed. Specifically, for example, a part of the thick silicon layer 101 of the substrate 100 is removed by the above-described Bosch process, and a part of the etch stopper layer 102 of the substrate 100 is removed by reactive ion etching (RIE) using CHF ₃ gas. Remove. The etch stopper layer 102 may be etched isotropically with buffered hydrofluoric acid or dilute hydrofluoric acid, or may be isotropically etched in a gas phase using a mixed gas of anhydrous HF and alcohol.

  Thereafter, the second protective film R and the bonding means B are removed, and a process such as dicing is performed to complete the acceleration sensor 1 shown in FIG.

  According to the manufacturing method described above, all the side surfaces and the weight portions of the beam portions F1, F2, F3, and F4 are etched by etching using the two patterns of the protective film R formed on the back surface that is one of the two main surfaces of the substrate 100. Since all the side surfaces of M are formed, the alignment accuracy between the beam portions F1, F2, F3, and F4 and the weight portion M can be increased. As a result, the shape accuracy of the movable part of the acceleration sensor 1 can be increased. Further, since the contours of the two patterns of protective films necessary for forming all the side surfaces of the beam portions F1, F2, F3, and F4 and all the side surfaces of the weight portion M can be controlled by one exposure, The alignment accuracy of the parts F1, F2, F3, F4 and the weight part M can be further increased. As a result, the shape accuracy of the movable part of the acceleration sensor 1 can be further increased.

2. Second Embodiment FIGS. 7A, 7B, 7C, and 7D show a six-axis motion sensor that is a MEMS sensor manufactured according to a second embodiment of the present invention. The motion sensor 2 is a die constituting a MEMS sensor for detecting a triaxial acceleration component orthogonal to each other and a triaxial angular velocity component orthogonal to each other.

  The motion sensor 2 includes a support S having a rectangular frame shape, a cantilever beam F having a fixed end coupled to the support S, and a weight M coupled to a free end of the beam F. And a piezoresistive element 40 as a strain detecting means and a piezoelectric element P as a strain detecting means or a driving means, and are accommodated in a package (not shown). These structural elements and electrical functional elements constituting the motion sensor 2 include a substrate 100 made of a plate-like bulk material, a silicon layer 104, an insulating layer 106, a wiring layer 108, a piezoelectric layer 110, an electrode layer 112, and a protection. The layer 114 and the wiring layer 115 are configured by a laminated structure in which the layers 114 and the wiring layer 115 are integrally bonded.

  The support portion S is a frame-shaped structural element for supporting the four beam portions F. The support portion S includes a substrate 100, a thin silicon layer 104, an insulating layer 106, and a protective layer 114. The support portion S is a multilayer structure including the substrate 100 that is sufficiently thicker than the beam portion F. Therefore, the support portion S is not substantially deformed.

  The four beam portions F having the same form are arranged in a cross shape inside the support portion S, and one end of each is coupled to the support portion S and the other end is coupled to the weight portion M. Each beam portion F includes a thin silicon layer 104, an insulating layer 106, and a protective layer 114.

  The weight portion M has a form in which a rectangular parallelepiped portion is coupled to four corners of a substantially rectangular parallelepiped central portion coupled to the beam portion F. The weight portion M includes a substrate 100 that is sufficiently thicker than the beam portion F. Therefore, the weight part M behaves as a rigid body that moves relative to the support part S.

The weight part M, the support part S, and the beam part F are separated by four slits H which are through holes.
A total of twelve piezoresistive elements 40 are provided in a proximity region of the beam portion F with the support portion S and a proximity region with the weight portion M. The piezoresistive element 40 is formed in the silicon layer 104. The direction of the stress generated by the deformation of the beam portion F is reversed between the front surface and the back surface of the beam portion F. For this reason, the piezoresistive element 40 is thinly formed near the interface of the silicon layer 104. The piezoresistive elements 40 form a bridge circuit with a set of four, and are wired so that output signals corresponding to three-axis acceleration components orthogonal to each other can be extracted from each bridge circuit.

  The piezoelectric element P is provided on the surface of the thin silicon layer 104. The piezoelectric element P has a structure in which the piezoelectric layer 110 is sandwiched between the wiring layer 108 functioning as an electrode and the electrode layer 112. A part of the plurality of piezoelectric elements P functions as a driving unit that circulates the weight part M by distorting the beam part F, and the remaining part is a detection unit that detects distortion of the beam part F caused by Coriolis force due to angular velocity. Function as.

(Production method)
A method for manufacturing the motion sensor 2 will be described with reference to FIGS.
First, the laminated structure W shown in FIG. 8 in which a three-dimensional mechanical structure is not formed is formed by a known method in which a thin film is laminated, modified, or etched on the surface of the substrate 100. For example, the substrate 100, the thin silicon layer 104, the insulating layer 106 are formed in the same manner as in the first embodiment, the piezoresistive element 40 is formed, and then the wiring layer 108 made of platinum (Pt) having a thickness of 0.1 μm is formed. It is formed over the entire surface of the insulating layer 106. Next, a piezoelectric layer 110 made of PZT (lead zirconate titanate) having a thickness of 3 μm is formed on the entire surface of the wiring layer 108 by a sputtering method or a sol-gel method. Next, an electrode layer 112 made of platinum and having a thickness of 0.1 μm is formed on the entire surface of the piezoelectric layer 110. Thereafter, the electrode layer 112, the piezoelectric layer 110, and the wiring layer 108 are sequentially etched using three kinds of protective films. Next, a protective layer 114 made of photosensitive polyimide and having a thickness of 10 μm is formed, and contact holes are formed by exposure and development. Next, a wiring layer 115 made of aluminum (Al) connected to the wiring layer 108 and the electrode layer 112 exposed from the contact hole is formed. Next, when the wiring layer 115 is patterned by etching, a laminated structure W shown in FIG. 8 is obtained.

  Next, as shown in FIG. 9A, FIG. 9B, and FIG. 9C, the laminated structure W is temporarily bonded to the sacrificial substrate 99 using the bonding means B, and then the second structure is formed on the back surface of the substrate 100 as in the first embodiment. One protective film R is formed. The first protective film R is made of a photoresist which is a photosensitive resin, and has a thin portion R2 for forming the beam portion F thinner than the support portion S and the weight portion M shown in FIG. It has a thick part R1 for forming S and the weight part M thicker than the beam part F. Further, the first protective film R is formed with a slit RS which is a first through hole for forming the slit H which is the through hole shown in FIG. The thickness of the thick portion R1 is, for example, 10 μm, and the thickness of the thin portion R2 is, for example, 3 μm.

  Next, as shown in FIG. 10A and FIG. 10B, etching is performed until the laminated structure W exposed from the slit RS of the first protective film R penetrates, as in the first embodiment. At this time, a slit H which is a through hole separating the support portion S, the beam portion F, and the weight portion M shown in FIG. 7 is formed at one time.

  Next, as shown in FIGS. 11A and 11B, as in the first embodiment, the entire surface of the first protective film R made of photoresist is etched until the thin-walled portion R2 disappears. A hole RT is formed, and a second protective film R composed of the remainder of the first protective film R is formed. At this time, the pattern of the second protective film R is accurately formed in a self-aligned manner by the pattern of the thick portion R1 of the first protective film R. Further, by leaving the edge of the thick portion R1 of the first protective film R, which forms a part of the side surface of the weight portion M that is separated from the beam portion F, in the second protective film R, the side surface of the weight portion M is left. The part spaced apart from the beam part F is determined by the pattern of the thick part R1.

  Next, as shown in FIGS. 12A and 12B, the beam portion of the substrate 100 is etched by etching the substrate 100 exposed from the second through hole RT of the second protective film R, as in the first embodiment. The portion overlapping F is removed, the thickness of the beam portion F is adjusted, and the remaining portion Ms made of the substrate 100 on the side surface of the weight portion M is formed. As a result, the beam portion F and the weight portion M shown in FIG. 7 are completed.

  Also in this embodiment, all the side surfaces of the beam portion F and all the side surfaces of the weight portion M are formed by etching using the two patterns of the protective film R on the back surface which is one of the two main surfaces of the substrate 100. The alignment accuracy between the beam portion F and the weight portion M can be increased. Further, since the contours of the two patterns of protective films necessary for forming all the side surfaces of the beam portion F and all the side surfaces of the weight portion M can be controlled by one exposure, the beam portion F and the weight portion M are controlled. The positioning accuracy can be further increased.

3. Third Embodiment As shown in FIGS. 13 to 16, the first protective film may be transformed into a second protective film by laser ablation.
Specifically, as shown in FIGS. 13A, 13B, and 13C, a single-layer first protective film R made of a photosensitive material having a uniform thickness is formed on the back surface of the substrate 100. In the first protective film R, slits RS which are first through holes for forming the slits H1 and H2 which are the through holes shown in FIG. 1 are formed. The thickness of the first protective film R is, for example, 10 μm.

  Next, as shown in FIG. 14A and FIG. 14B, etching is performed until the laminated structure W exposed from the slit RS of the first protective film R penetrates, as in the first embodiment.

  Next, as shown in FIGS. 15A and 15B, the second protective film R that overlaps the beam portions F1, F2, F3, and F4 of the substrate 100 shown in FIG. 1 is removed by laser ablation. Through-holes RT, and a second protective film R made of the remaining portion of the first protective film R is formed. At this time, by leaving the edge of the first protective film R, which forms portions spaced from the beam parts F1, F2, F3, and F4 on the side surface of the weight part M, in the second protective film R, the weight part The portions spaced apart from the beam portions F1, F2, F3, and F4 on the side surface of M are determined by the pattern of the first protective film R.

  Next, as shown in FIGS. 16A and 16B, similarly to the first embodiment, the beam portion of the substrate 100 is etched by etching the substrate 100 exposed from the second through hole RT of the second protective film R. The portions overlapping F1, F2, F3, and F4 are removed, the thicknesses of the beam portions F1, F2, F3, and F4 are adjusted, and the remaining portion Ms made of the substrate 100 on the side surface of the weight portion M is formed. As a result, the beam portions F1, F2, F3, and F4, the weight portion M, and the support portion S shown in FIG. 1 are completed.

  In the present embodiment, two patterns of protective films necessary for forming all the side surfaces of the beam portions F1, F2, F3, and F4 and all the side surfaces of the weight portion M are one of the main surfaces of the substrate 100. Since it forms on a back surface, the alignment precision of beam part F1, F2, F3, F4 and the weight part M can be raised. In addition, since the second protective film is formed by removing a part of the single-layer first protective film, a step of adding a material for the second protective film is unnecessary.

4). Fourth Embodiment A second protective film formed on the back surface which is one of the main surfaces of the substrate 100 is not a modification of the first protective film, but is newly formed after the first protective film is completely removed. You may do it. Specifically, as shown in FIGS. 14A and 14B, the first protective film R is removed after etching until the layered structure W is penetrated. Next, a second protective film R shown in FIGS. 15A and 15B may be formed on the back surface of the substrate 100.

  Also in this embodiment, all of the side surfaces of the beam portions F1, F2, F3, and F4 and the weight portion M are etched by etching using the two patterns of the protective film R formed on the back surface that is one of the two main surfaces of the substrate 100. Since all the side surfaces are formed, the alignment accuracy between the beam portions F1, F2, F3, and F4 and the weight portion M can be increased.

5). Fifth Embodiment As shown in FIGS. 17 to 20, the first protective film may have a multilayer structure, and the first protective film may be transformed into the second protective film by selective etching.

Specifically, as shown in FIGS. 17A and 17B, a first protective film R having a two-layer structure including a lower layer portion RP and an upper layer portion RR that can be selectively removed is formed on the back surface of the substrate 100. . For example, after a lower layer portion RP made of Si _x N _y , SiO ₂ , Al or the like having a thickness of 2 μm is formed on the entire back surface of the substrate 100, an upper layer portion RR made of a photoresist having a thickness of 10 μm is formed on the entire surface of the lower layer portion RP. Form. Next, a slit RS is formed in the upper layer portion RP by exposure and development through a mask. Next, when the lower layer portion RP exposed from the slit RS of the upper layer portion RP is etched to penetrate the slit RS to the back surface of the substrate 100, a first protective film R having a two-layer structure is formed.

  Next, as shown in FIG. 18A and FIG. 18B, etching is performed until the laminated structure W exposed from the slit RS of the first protective film R penetrates, as in the first embodiment.

  Next, as shown in FIGS. 19A and 19B, the upper layer portion RR is removed by etching, and the exposed lower layer portion RP is patterned by laser ablation, whereby the first protective film R is used as the second protective film composed of the remaining portion. It transforms into the lower layer part RP. At this time, by leaving the edge of the lower layer portion RP of the first protective film R in which the portions separated from the beam portions F1, F2, F3, and F4 on the side surface of the weight portion M are left, the side surface of the weight portion M is left. The portions separated from the beam portions F1, F2, F3, and F4 are determined by the pattern of the first protective film R.

  Next, as shown in FIGS. 20A and 20B, the beam portion of the substrate 100 is etched by etching the substrate 100 exposed from the second through hole RT of the second protective film R, as in the first embodiment. The portions overlapping F1, F2, F3, and F4 are removed, the thicknesses of the beam portions F1, F2, F3, and F4 are adjusted, and the remaining portion Ms made of the substrate 100 of the weight portion M is formed. As a result, the beam portions F1, F2, F3, F4 and the weight portion M shown in FIG. 1 are completed.

  In this embodiment, the two patterns of protective films necessary to form all the side surfaces of the beam portions F1, F2, F3, and F4 and all the side surfaces of the weight portion M are one of the main surfaces of the substrate 100. Since it forms on a back surface, the alignment precision of beam part F1, F2, F3, F4 and the weight part M can be raised.

6). Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention. For example, the materials, dimensions, film forming methods, and pattern transfer methods shown in the above embodiments 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. ing. For example, the present invention can also be applied to other MEMS sensors such as vibration sensors.

The top view concerning a first embodiment of the present invention. Sectional drawing corresponding to the BB line shown to FIG. 1A. Sectional drawing corresponding to CC line shown to FIG. 1A. Sectional drawing corresponding to the DD line shown to FIG. 1A. Process sectional drawing corresponding to the BB line shown to FIG. 1A. Process sectional drawing corresponding to the BB line shown to FIG. 1A. Process sectional drawing corresponding to the DD line shown to FIG. 1A. The top view concerning the process corresponding to FIG. 3A and FIG. 3B. Process sectional drawing corresponding to the BB line shown to FIG. 1A. Process sectional drawing corresponding to the DD line shown to FIG. 1A. Process sectional drawing corresponding to the BB line shown to FIG. 1A. Process sectional drawing corresponding to the DD line shown to FIG. 1A. Process sectional drawing corresponding to the BB line shown to FIG. 1A. Process sectional drawing corresponding to the DD line shown to FIG. 1A. The top view concerning 2nd embodiment of the present invention. Sectional drawing corresponding to the BB line shown to FIG. 7A. Sectional drawing corresponding to CC line shown to FIG. 7A. The bottom view concerning a second embodiment of the present invention. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. The top view concerning the process corresponding to FIG. 7A and FIG. 7B. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. The top view corresponding to FIG. 13A and FIG. 13B. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A. Process sectional drawing corresponding to the BB line shown to FIG. 7A. Process sectional drawing corresponding to CC line shown to FIG. 7A.

Explanation of symbols

1: acceleration sensor, 2: motion sensor, 40: piezoresistive element, 41: connection resistance reducing unit, 42: resistance unit, 99: sacrificial substrate, 100: substrate, 101: silicon layer, 102: etch stopper layer, 104: Silicon layer, 106: insulating layer, 108: wiring layer, 110: piezoelectric layer, 112: electrode layer, 114: protective layer, 115: wiring layer, B: bonding means, F: beam portion, H: slit, M: weight Part, P: piezoelectric element, R: protective film, R1: thick part, R2: thin part, RP: lower layer part, RR: upper layer part, RS: slit, RT: through hole, S: support part, W: lamination Structure

Claims (6)

A support part;
A beam part having one end coupled to the support part and thinner than the support part;
A weight portion coupled to the other end of the beam portion and thicker than the beam portion;
Strain detection means provided on the beam portion for detecting strain of the beam portion;
A method of manufacturing a MEMS sensor comprising:
By laminating a film on the surface of the substrate, a laminated structure including the strain detecting means constituted by the film and the substrate is formed,
Forming a first protective film in which a first through-hole is formed and a second protective film in which a second through-hole is formed on the back surface of the substrate;
Etching until penetrating the laminated structure exposed from the first through hole, thereby forming a side surface of the beam portion and a portion spaced from the beam portion of the side surface of the weight portion,
Adjusting the thickness of the beam portion by etching the substrate exposed from the second through-hole and forming the remaining portion of the substrate on the side surface of the weight portion;
A method for manufacturing a MEMS sensor. Forming the first protective film of a single layer having a thin part and a thick part thicker than the thin part on the back surface of the substrate;
The first protective film is etched by etching the entire surface of the first protective film until the thin portion disappears after etching through the laminated structure exposed from the first through hole. Forming the second protective film consisting of the remainder of
The manufacturing method of the MEMS sensor of Claim 1 including this. Forming a photosensitive resin film on the back surface of the substrate;
Exposing the photosensitive resin film through a multi-tone mask;
Forming the thin part and the thick part by developing the exposed photosensitive resin film;
The manufacturing method of the MEMS sensor of Claim 2 including this. An entire surface of the first protective film is anisotropically etched to include an edge of a thick portion of the first protective film that forms a part of the side surface of the weight portion that is separated from the beam portion. Forming the second protective film;
The manufacturing method of the MEMS sensor of Claim 2 or 3 including this. Forming the first protective film having a uniform thickness on the back surface of the substrate;
After etching the laminated structure exposed from the first through hole, the part of the first protective film is removed by laser ablation so as to be separated from the beam part on the side surface of the weight part. Forming the second protective film composed of the remaining part of the first protective film including the edge of the first protective film in which the portion being formed is formed;
The manufacturing method of the MEMS sensor of Claim 1 including this. Forming the first protective film consisting of a lower layer portion to be the second protective film and an upper layer portion made of a material that can be etched leaving the lower layer portion on the entire back surface of the substrate;
After etching the laminated structure exposed from the first through hole, the lower layer portion is exposed by removing the upper layer portion by etching,
The second portion comprising the remaining portion of the lower layer portion including the edge of the lower layer portion in which a portion spaced from the beam portion on the side surface of the weight portion is formed by removing a part of the lower layer portion by laser ablation. Forming a protective film,
The manufacturing method of the MEMS sensor of Claim 1 including this.

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