JP4599510B2 - Piezoelectric vibration type inertial sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a piezoelectric vibration type inertial sensor configured using a piezoelectric element and a method for manufacturing the same.

6 to 10 of Japanese Patent Application Laid-Open No. 11-83497 (Patent Document 1) include a silicon substrate, a base disposed so as to surround the periphery of the substrate at a predetermined interval, and a silicon substrate. Four support beams for supporting the substrate with respect to the base at the node when the substrate vibrates, a vibration drive unit composed of a piezoelectric element formed on one surface of the silicon substrate, and on the other surface of the silicon substrate A structure of a conventional piezoelectric vibration type inertial sensor including a vibration detection unit formed of a piezoelectric element is shown.
6 to 10 of Japanese Patent Laid-Open No. 11-83497 (Patent Document 1)

  In the conventional inertial sensor, the piezoelectric thin film layer and the metal electrode layer for constituting the vibration drive unit and the vibration detection unit must be formed from the two front and back surfaces of the substrate, and the film formation surface is set during the process. There is a problem that productivity is reduced because repair is required. In addition, an expensive apparatus capable of performing double-sided film formation is required, leading to a problem of increasing the cost of the sensor.

  Moreover, since it is necessary to form the electrode lead part on the back surface so as to straddle the step part of the etching inclined surface of the substrate, there is a problem that it is difficult to manufacture.

  The piezoelectric vibration type inertial sensor of the present invention includes a flexible substrate, a base disposed so as to surround the periphery of the substrate with a predetermined interval between the substrate, and a substrate when the substrate is flexibly vibrated. A first pair of support beams for supporting the substrate with respect to the base in the first node, and a second pair of supports for supporting the substrate with respect to the base in the second node when the substrate is flexibly vibrated. And a support beam. Then, a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer are laminated on one side of the substrate so as to be arranged in a direction orthogonal to the direction in which the first and second nodes are arranged. A vibration drive unit and a vibration detection unit including the above piezoelectric elements are provided.

  According to the inertial sensor of the present invention, since the vibration driving unit and the vibration detection unit are formed on one surface of the substrate, it is not necessary to reset the film formation surface during production, and the productivity is increased. Further, since the price of the manufacturing apparatus can be reduced, the cost of the product can be greatly reduced.

  The vibration drive unit and the vibration detection unit are configured by laminating a lower electrode layer, a first piezoelectric thin film layer, an intermediate electrode layer, a second piezoelectric thin film layer, and an upper electrode layer, respectively. You may comprise from 1 or more piezoelectric elements. In this case, the first piezoelectric thin film layer and the second piezoelectric thin film layer are polarized in opposite directions. With such a bimorph structure, the detection output can be increased. In this case, if the substrate is made of an insulating thin film or sheet, the substrate can be prevented from being subjected to vibration and the output can be further increased.

  The substrate is preferably made of a flexible resin substrate such as a silicon substrate, a glass substrate, a metal plate, polyimide, or a composite substrate in which a flexible resin substrate is laminated on a metal plate. With these substrates, desired flexibility and mechanical strength can be easily obtained, and the substrate can be formed at low cost.

  Furthermore, at least the lower electrode layer can be formed of any metal thin film such as aluminum, silver, gold, copper, or platinum. The upper electrode layer may also be formed of the same metal thin film as the lower electrode layer. Further, the intermediate electrode layer in the case of the bimorph structure is formed of a metal thin film having a body-centered cubic lattice structure such as molybdenum. When a metal thin film having such a crystal structure having a body-centered cubic lattice structure is used, the polarization directions of the first piezoelectric thin film layer and the second piezoelectric thin film layer are reversed, that is, reversed.

  The piezoelectric thin film layer may be composed of at least one of an aluminum nitride thin film, a gallium nitride thin film, an indium nitride thin film, a zinc sulfide thin film, a lithium niobate thin film, a zinc oxide thin film, and a lithium tantalate thin film. it can. In this case, it is desirable that the piezoelectric thin film has a dipole orientation degree of 55% or more. Here, the degree of dipole orientation is calculated by calculating the ratio of the higher plus or minus occupancy in the polarization direction of the piezoelectric thin film surface. When the dipole orientation degree is 50%, the plus and minus amounts are equal and no signal is output. Therefore, it is ideal that the state is biased to either plus or minus. There is a correlation between the degree of dipole orientation and the amount of charge accumulated in the piezoelectric element. That is, the higher the degree of dipole orientation, the higher the voltage the piezoelectric element can store, resulting in higher performance. Theoretically, a signal is output if there is a slight difference such as 50.1%, for example. However, as a result of measuring the presence or absence of a signal due to a deviation in the degree of dipole orientation, there is no deviation of 55% or more. In some cases, since it is difficult to measure, a thin film having a dipole orientation degree of 55% or more was used as a piezoelectric thin film. When such an electrode layer and a piezoelectric thin film layer are used, the piezoelectric effect is enhanced and the detection output can be increased. In particular, when an aluminum nitride thin film is used as the piezoelectric thin film layer, since it has high heat resistance such as piezoelectricity even at 1200 ° C. or higher, an inertial sensor that is easy to manufacture, has heat resistance stability, and has good temperature characteristics can be obtained. .

  When the above-mentioned piezoelectric thin film is formed on a thin film made of aluminum, silver, gold, copper, platinum or the like having a face-centered cubic lattice crystal structure, it is spontaneously polarized. There is an advantage that no polarization treatment is required.

  Alternatively, the lower electrode layer of the vibration drive unit and the lower electrode layer of the vibration detection unit may be formed continuously to form one common electrode layer. Alternatively, the piezoelectric thin film layer of the vibration driving unit and the piezoelectric thin film layer of the vibration detecting unit may be continuously formed to form one common piezoelectric thin film layer. In this way, the manufacturing process can be reduced, and the manufacturing cost of the inertial sensor can be reduced.

  Specifically, a pair of input electrodes for the vibration drive unit and a pair of output electrodes for the vibration detection unit are formed on the base. The lower electrode layer and the upper electrode layer of the vibration drive unit and the pair of input electrodes are connected to each other via lead lines formed on the two support beams selected from the first and second pair of support beams. Can be connected. In addition, the lower electrode layer and the upper electrode layer of the vibration detection unit and the pair of output electrodes are formed of lead lines respectively formed on two other support beams selected from the first and second pair of support beams. Can be connected through. In this way, electrical connection can be performed easily and reliably.

  In the case where the substrate includes an extension portion that extends outward in the longitudinal direction beyond the first and second pair of support beams, one or more thin film layers are formed as balance weights on one surface of the extension portion. May be.

  When manufacturing the inertial sensor of the present invention, the first step of forming the vibration drive unit and the vibration detection unit on one surface of the semiconductor substrate, and etching the semiconductor substrate to produce the vibration drive unit and the vibration detection unit. A flexible substrate having a substrate, a base disposed so as to surround the periphery of the substrate at a predetermined interval, and a substrate at a first node when the substrate is flexibly vibrated. A sensor body integrally including a first pair of support beams to be supported with respect to the base and a second pair of support beams to support the substrate with respect to the base at a second node when the substrate is flexibly vibrated. The second step of forming is performed. In the first step, on the surface region located between the first and second nodes on one side of the substrate, the first and second nodes are arranged in a direction orthogonal to the direction in which the first and second nodes are arranged, respectively. A vibration drive unit and a vibration detection unit configured by one or more piezoelectric elements having a structure in which a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer are stacked are formed.

  Also, a first step of forming an oxide film on one surface of the semiconductor substrate, and forming a vibration drive unit and a vibration detection unit on the oxide film, and etching the semiconductor substrate to provide a vibration drive unit and a vibration detection unit. A flexible substrate provided with a portion, a base disposed so as to surround the periphery of the substrate with a predetermined gap between the substrate, and a substrate at a first node when the substrate is flexibly vibrated A first pair of support beams that support the substrate with respect to the base and a second pair of support beams that support the substrate with respect to the base at the second node when the substrate is flexibly vibrated. And a second step of forming the main body. In the first step, on the surface region located between the first and second nodes on one side of the substrate, the first and second nodes are arranged in a direction orthogonal to the direction in which the first and second nodes are arranged, respectively. A vibration drive unit and a vibration detection unit configured by one or more piezoelectric elements having a structure in which a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer are stacked are formed. Finally, after the second step, a third step of removing the substrate is performed. In this way, a bimorph type piezoelectric element can be easily formed. In addition, an inertial sensor can be obtained in which the neutral surface of the vibration part is substantially coincident with the center of the bimorph structure so that vibration can be efficiently driven and vibration can be detected efficiently.

  According to the inertial sensor of the present invention, since the vibration driving unit and the vibration detection unit are formed on one surface of the substrate, it is not necessary to reset the film formation surface during production, and the productivity is increased. Further, since the price of the manufacturing apparatus can be reduced, there is an advantage that the cost of the product can be greatly reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a piezoelectric vibration type inertial sensor of the present invention in which a substrate is formed using a semiconductor substrate, FIG. 2 is a sectional view taken along line BB in FIG. 1, and FIG. It is line sectional drawing. FIG. 4 is a diagram showing the manufacturing process of the embodiment of FIG. 1 in time series. In these drawings, a member denoted by reference numeral 1 is a sensor body. The sensor body 1 is formed by etching a semiconductor substrate, and includes a base 3, a substrate 5, and four support beams 7 to 13. The base body 3 has a through hole 4 in the center, and has a frame shape in which a contour shape seen from above forms a rectangular shape. The substrate 5 is located in the through hole 4 of the base 3, is thinner than the base 3, and has a rectangular shape. The substrate 5 is connected to the base 3 surrounding the substrate 5 by first to fourth support beams 7 to 13. Among the support beams 7 to 13, the first pair of support beams 7 and 9 support the substrate 5 with respect to the base 3 at the first node N <b> 1 when the substrate 5 is flexibly vibrated. The second pair of support beams 11 and 13 support the substrate 5 with respect to the base 3 at the second node N2 when the substrate 5 is flexibly vibrated. And on one side 6 of the substrate 5, the oxide layer 14 as an insulating protective film made of SiO ₂ is formed. Then, the vibration drive is performed so that the first and second nodes N1 and N2 are arranged in a direction orthogonal to the direction in which the first and second nodes N1 and N2 are arranged on the surface region located between the first and second nodes N1 and N2 on one side 6. A unit 15 and a vibration detection unit 17 are provided.

  The vibration drive unit 15 and the vibration detection unit 17 are each composed of one piezoelectric element having a structure in which lower electrode layers 19 and 21, piezoelectric thin film layers 23 and 25, and upper electrode layers 27 and 29 are stacked. Yes. The lower electrode layer 19 of the vibration driving unit 15 is connected to a first input electrode 33 formed on the base 3 through a lead line 31 extending on the third support beam 11. The upper electrode layer 27 is connected to a second input electrode 37 formed on the base 3 through a lead line 35 extending on the first support beam 7. The lower electrode layer 21 of the vibration detection unit 17 is connected to a first output electrode 41 formed on the base 3 through a lead line 39 extending on the second support beam 9. The upper electrode layer 29 is connected to a second output electrode 45 formed on the substrate 3 through a lead line 43 extending on the third support beam 13. The lower electrode layers 19 and 21 each have a rectangular shape extending along the longitudinal direction of the substrate 3. In this example, the piezoelectric thin film layers 23 and 25 of the vibration driving unit 15 and the vibration detecting unit 17 are constituted by one piezoelectric thin film layer. The piezoelectric thin film layer 23 prevents the lead wire 35 and the lower electrode layer 19 from being electrically short-circuited. The piezoelectric thin film layer 25 prevents the lead wire 43 and the lower electrode layer 21 from being electrically short-circuited.

  In the present embodiment, the sensor body 1 is constituted by a semiconductor substrate (silicon substrate). However, at least the substrate 5 may be formed of a flexible material substrate such as a glass substrate, a metal plate, or a flexible resin such as polyimide. When the substrate 5 is formed of a conductive or semiconductive material such as a metal plate or a semiconductor substrate, the surface thereof is oxidized or nitrided, or formed thereon by a thin film layer forming method such as sputtering. An insulating layer may be formed.

  The lower electrode layers 19 and 21 and the upper electrode layers 27 and 29 are formed by laminating one or more of aluminum, silver, gold, copper, platinum, and alloys thereof by EB vapor deposition or sputtering. When the lower electrode layers 19 and 21 constitute a ground electrode, both electrode layers may be constituted by one electrode layer.

  The piezoelectric thin films 23 and 25 are made of at least one of an aluminum nitride thin film, a gallium nitride thin film, an indium nitride thin film, a zinc sulfide thin film, a lithium niobate thin film, a zinc oxide thin film, and a lithium tantalate thin film. Can do. Particularly in the present embodiment, the piezoelectric thin film is formed of an aluminum nitride thin film. In the present embodiment, the piezoelectric thin films 23 and 25 are formed by one piezoelectric thin film layer, but it is needless to say that both may be formed by separate piezoelectric thin film layers.

  The four support beams 7 to 13 according to the present embodiment are arranged at nodes (node portions) in the primary vibration mode in the longitudinal direction of the substrate when the substrate 5 vibrates. In the present embodiment, for example, an AC voltage of 5 to 50 kHz is applied between the input electrodes of the drive vibration unit 15. This causes the substrate 5 to bend and vibrate in the vertical direction. As described above, if the inertial sensor rotates around the axis of the substrate 5 while the cantilever vibrating body is flexibly vibrating, the substrate 5 also vibrates in the horizontal direction due to the Coriolis force. Due to the vibration in the horizontal direction, voltages having opposite polarities are generated between the pair of output electrodes of the vibration detector 17. By differentially amplifying the reverse polarity voltage, the rotational angular velocity based on the Coriolis force can be detected.

  The manufacturing method of the present embodiment will be described with reference to FIG. First, a silicon substrate 101 having a thickness of 200 to 300 μm is prepared. Next, an etching mask layer 102 is formed on the front and back surfaces of the silicon substrate 101. Then, anisotropic etching is performed from the back side of the silicon substrate 101 to form a recess 103 in the silicon substrate 101. Next, after removing the mask layer 102, an oxidation process is performed on the entire substrate constituting the membrane portion to form an oxide film 104. Next, lower electrode layers 19 and 21 made of aluminum are formed on the surface of the silicon substrate 101. At the same time, lead lines 31 and 39 and electrodes 33 and 41 are also formed. Since the lower electrode layers 19 and 21, the lead lines 31 and 39, and the electrodes 33 and 41 use a conductor as an electrode material, a physical vapor deposition method (PVD (Physical Vapor Deposition) method) is applied to a predetermined metal or alloy. It is formed by vapor deposition. Physical vapor deposition methods include vacuum deposition methods such as resistance heating deposition or electron beam heating deposition, various sputtering methods such as direct current sputtering, high frequency sputtering, RF plasma assisted sputtering, magnetron sputtering, ECR sputtering or ion beam sputtering, and high frequency ions. Various ion plating methods such as plating, activated vapor deposition or arc ion plating, molecular beam epitaxy, laser application, ionized cluster beam vapor deposition, and ion beam vapor deposition can be used. . Among these, it is more preferable to use the sputtering method. Specifically, the film may be formed by vapor deposition or sputtering after masking in a predetermined shape in advance, but may be patterned by etching or the like after film formation.

  The film forming conditions such as the lower electrode layer can be, for example, a pressure of 1.0 × 10 −1 Pa, a nitrogen gas partial pressure ratio of 0%, a substrate temperature of no heating, and a target input power of 200 W. Moreover, the film thickness to form can be changed with materials. However, the above conditions can be changed as appropriate. Then, using the film forming conditions and the vapor deposition method, a lower electrode layer and the like having good matching with the (0002) plane of aluminum nitride to be formed later are formed. By forming such a lower electrode layer or the like in the above temperature range, a lower electrode layer or the like suitable for forming a dipole-oriented aluminum nitride thin film can be formed.

  Thereafter, the piezoelectric thin film layers (23, 25) are formed so as to extend over the entire lower electrode layers 19, 21. In the present embodiment, a piezoelectric thin film made of an aluminum nitride thin film having a dipole orientation degree of 55% or more is formed. The piezoelectric thin film is preferably formed by using a PVD method, particularly a sputtering method. As described above, the metal forming the lower electrode layer is a crystal having the same arrangement as the atomic arrangement of the (0002) plane of aluminum nitride, and approximately the same atomic spacing as that of the (0002) plane of aluminum nitride. More preferably, the plane is oriented parallel to the substrate. Such a metal forms a base surface equivalent to that of a single crystal such as sapphire, so that a dipole orientation is obtained by forming a thin film on the lower electrode layer using aluminum as a target using the PVD method. Thus, a piezoelectric thin film made of aluminum nitride can be obtained.

  Sputtering can be performed using, for example, a high-frequency magnetron sputtering apparatus. In this case, vacuuming is performed in the sputtering chamber so that the pressure is 5 × 10 −4 Pa or less, and high-purity argon gas (purity 99.999%) and high-purity nitrogen gas (purity 99.999%) or high-purity oxygen gas are used. (Purity 99.999%). Before vapor deposition, aluminum sputtering as a target is performed for 10 minutes while the shutter of the high-frequency magnetron sputtering apparatus is closed. Then, for example, sputtering is performed under film forming conditions in which the sputtering pressure is 0.5 Pa, the substrate temperature is 400 ° C., the nitrogen gas partial pressure ratio is 50%, the target input power is 400 W, and the sputtering time is 4 hours. A thin film can be formed. The piezoelectric thin film layers (23, 25) are previously masked into a predetermined shape and then formed by sputtering, CVD, or the like, or patterned by etching or the like after formation. The aluminum nitride thin film thus formed provides an aluminum nitride thin film having a dipole orientation degree of about 80% and a rocking curve showing a dipole orientation degree of the piezoelectric thin film layer having a half-width of 3 degrees.

  Next, upper electrode layers 27 and 29, lead lines 35 and 43, and electrodes 37 and 45 are formed simultaneously. These upper electrode layers and the like are formed in the same manner as the lower electrode layers 19 and 21. The upper electrode layer, the connection line, and the output electrode made of any of the materials used for forming the lower electrode layer described above are formed using a vapor deposition method such as a PVD method or a CVD (Chemical Vapor Deposition) method. Note that the upper electrode layer having a stacked structure may be formed using a plurality of substances among the substances used for the upper electrode layer.

  Finally, etching is performed so as to leave the substrate 5 and the support beams 7 to 13 and the thin film formed thereon, and a gap g is formed between the base 3 and the substrate 5 to complete the inertial sensor.

  FIG. 5 is a plan view of the piezoelectric vibration type inertial sensor according to the second embodiment of the present invention. This embodiment is different from the embodiment shown in FIGS. 1 to 4 in that the vibration detectors (117a, 117b) are divided into two parts, and a thin film layer (115 ′ for weight balance). 117 ′). Since the other points are the same as in the above embodiment, the same reference numerals as those shown in FIG. 1 are given the same number as the number shown in FIG. Description is omitted. In the present embodiment, a common lower electrode layer that can be used in common for both the vibration drive unit 115 and the vibration detection units (117a, 117b) as a lower electrode layer (not shown) is formed on one surface of the substrate 5. is there. The upper electrode layers 129a and 129b are divided into two parts in order to form divided vibration detection parts 117a and 117b obtained by dividing the vibration detection part in two. In this way, the same effects as those of the embodiment shown in FIGS. 1 to 4 can be obtained. In this embodiment, the outputs of the output electrodes 145a and 145b are combined to obtain a detection output. In this embodiment, when forming the vibration drive unit 115 and the vibration detection unit (117a, 117b), the extension 105a that extends outward in the longitudinal direction beyond the first and second pair of support beams 107-113. , 105b, one or more thin film layers 115 ′, 117 ′ are formed as balance weights. These thin film layers 115 ′ and 117 ′ are not electrically connected to the vibration drive unit 115 and the vibration detection unit (117a, 117b), but are layers of the vibration drive unit 115 and the vibration detection unit (117a, 117b). It has the same layer structure as the structure. By forming the thin film layers 115 ′ and 117 ′ as such balance weights, the actual deviation from the design resonance frequency of the vibration part, which is subtly generated by forming the electrode layer and the piezoelectric thin film layer in the vibration part, is reduced. It becomes possible to make it smaller.

  6 and 7 are a plan view of a piezoelectric vibration type inertial sensor according to a third embodiment of the present invention and a cross-sectional view taken along the line DD of FIG. This embodiment is different from the embodiment shown in FIGS. 1 to 4 in that the vibration drive unit 215 and the vibration detection unit 217 have a so-called bimorph structure. Since the other points are the same as those in the first embodiment, the same number as that shown in FIG. 1 is given the number of codes obtained by adding 200 to the number of codes given in FIG. A description thereof will be omitted. In the present embodiment, an intermediate electrode layer 226 is formed on the first piezoelectric thin film layer 223, and a second piezoelectric thin film layer 224 is further formed on the intermediate electrode layer 226, so that the second piezoelectric body is formed. Upper electrode layers 227 and 229 are formed on the thin film layer 224. The intermediate electrode layer 224 is not particularly connected to an electrode and is in an electrically floating state. The intermediate electrode layer 226 is formed of a metal thin film having a body-centered cubic lattice structure such as molybdenum. When such a metal thin film is used for the intermediate electrode layer, the first piezoelectric thin film layer 223 and the second piezoelectric thin film layer are polarized in opposite directions by spontaneous polarization. The second piezoelectric thin film layer 224 is also formed by the same method and material as the first piezoelectric thin film layer 223. In the present embodiment, it is preferable that the thickness of the substrate 5 be as thin as possible and the flexibility of the substrate 5 be as large as possible. In addition, the composition of the lower electrode layer 219 and the metal composition of the intermediate electrode layer 226 may be any as long as the crystal orientation of the piezoelectric thin film layer formed thereon is controlled to cause spontaneous polarization. .

  8 and 9 are a plan view of a piezoelectric vibration type inertial sensor according to a fourth embodiment of the present invention and a cross-sectional view taken along line EE of FIG. Parts similar to those shown in FIG. 1 are given the same reference numerals as those shown in FIG. The third embodiment has a bimorph structure as in the second embodiment shown in FIGS. The third embodiment is different from the second embodiment in that an insulating thin film 314 made of an oxide film forms a base and four support beams. The first and second piezoelectric thin film layers 323 and 324 are formed on the entire surface of the insulating thin film 314 and the four support beams 307 to 343. In this embodiment, the first and second piezoelectric thin film layers 323 and 324 are formed on one surface of the insulating thin film 314 and the four support beams 307 to 343 from the insulating thin film 314. This is because it is difficult to obtain sufficient mechanical strength with the substrate. The other points are the same as the structure of the embodiment of FIGS. According to the present embodiment, since the substrate is the thinnest, the presence of the substrate does not substantially affect the characteristics of the inertial sensor having the bimorph structure.

  FIG. 10 is a diagram showing a manufacturing process of the piezoelectric vibration type inertial sensor shown in FIGS. 8 and 9 in time series. Note that FIG. 10 is for showing the process, and the shape and dimensions of each part do not match those shown in FIGS. The manufacturing method of the present embodiment will be described with reference to FIG. First, a silicon substrate 301 having a thickness of 200 to 300 μm is prepared. Next, an etching mask layer 102 is formed on the front and back surfaces of the silicon substrate 301. Then, anisotropic etching is performed from the back side of the silicon substrate 301 to form a recess 303 in the silicon substrate 301. Next, an oxidation treatment is performed to form an oxide layer 304. Next, lower electrode layers 319 and 321 made of aluminum, lead lines 331 and 319 (not shown), and electrodes 33 and 41 are formed on the surface of the silicon substrate 301. The raw film conditions of the lower electrode layer are the same as those in the first embodiment shown in FIG.

  Thereafter, the lower electrode layers 319 and 321 are completely covered, and a first piezoelectric thin film layer 323 having a predetermined shape including the shapes of the base and the support beam is formed. In the present embodiment, a piezoelectric thin film made of an aluminum nitride thin film having a dipole orientation degree of 55% or more is formed. The first piezoelectric thin film is also formed in the same manner as in FIG.

  Next, an intermediate electrode layer 326 made of molybdenum is formed by vapor deposition at positions corresponding to the lower electrode layers 319 and 321 under the same conditions as those of the lower electrode layers 319 and 321 described above. Then, a second piezoelectric thin film layer 324 having the same shape as the first piezoelectric thin film layer 323 is formed on the intermediate electrode layer 326. The second piezoelectric thin film layer 324 also has a shape including the base and supporting beam portions.

  Next, upper electrode layers 327 and 329, lead lines 335 and 343, and electrodes 337 and 345 are formed simultaneously. The upper electrode layer and the like are formed by using a vapor deposition method such as a PVD method or a CVD (Chemical Vapor Deposition) method as in the formation of the lower electrode layers 319 and 321.

  Finally, the silicon substrate 301 is etched so as to leave portions corresponding to the first and second piezoelectric thin film layers 323 and 324 and the support beams 307 to 313, and the first and second piezoelectric thin film layers 323 and 323 The part of the silicon substrate located under 324 and the support beams 307 to 313 and the part of the silicon substrate located around the part are removed. Thereafter, the oxide film 304 remaining around the first and second piezoelectric thin film layers 323 and 324 and the support beams 307 to 313 is removed by etching to form a gap between the base 303 and the substrate 305.

  Compared with the embodiment shown in FIGS. 1 to 7, in the embodiment shown in FIGS. 8 to 10, the insulating thin film 314 formed by the oxide film 304 constitutes the substrate. In the case where the substrate is not formed using a silicon substrate, it is needless to say that the portion corresponding to the insulating thin film 314 may be formed of a synthetic resin sheet such as polyimide having a small thickness.

It is a top view of the piezoelectric vibration type inertial sensor of this invention which forms a board | substrate using a semiconductor substrate. It is the BB sectional view taken on the line of FIG. It is CC sectional view taken on the line of FIG. It is a figure shown in time series which shows the manufacturing process of embodiment of FIG. It is a top view of the piezoelectric vibration type inertial sensor of the 2nd Embodiment of this invention. It is a top view of the piezoelectric vibration type inertial sensor of the 3rd Embodiment of this invention. It is the DD sectional view taken on the line of FIG. It is a top view of the piezoelectric vibration type inertial sensor of the 4th Embodiment of this invention. It is the EE sectional view taken on the line of FIG. It is a figure which shows the manufacturing process of the piezoelectric vibration type inertial sensor shown in FIG.8 and FIG.9 in time series.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor main body 3,203 Base | substrate 5,205 Board | substrate 6 Single side | surface 7, 9, 11, 13 Support beam 15,215 Vibration drive part 17,217 Vibration detection part 19,21,219,221 Lower electrode layer 23,25 Piezoelectric body Thin film layer 27, 29, 227, 229 Upper electrode layer 223 First piezoelectric thin film layer 224 Second piezoelectric thin film layer 226 Intermediate electrode layer

Claims (9)

A flexible substrate;
A base disposed so as to surround the periphery of the substrate with a predetermined gap between the substrate and the substrate;
A first pair of support beams for supporting the substrate with respect to the base at a first node when the substrate is flexibly vibrated;
A second pair of support beams for supporting the substrate with respect to the base at a second node when the substrate is flexibly vibrated;
A structure in which a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer are stacked on one side of the substrate so as to be arranged in a direction orthogonal to the direction in which the first and second nodes are arranged. A vibration drive unit and a vibration detection unit composed of one or more piezoelectric elements ;
The substrate includes an extension that extends outward in the longitudinal direction beyond the first and second pair of support beams;
One or more thin film layers are formed as a balance weight on the one surface of the extension portion . A flexible substrate;
A base disposed so as to surround the periphery of the substrate with a predetermined gap between the substrate and the substrate;
A first pair of support beams for supporting the substrate with respect to the base at a first node when the substrate is flexibly vibrated;
A second pair of support beams for supporting the substrate with respect to the base at a second node when the substrate is flexibly vibrated;
A lower electrode layer, a first piezoelectric thin film layer, an intermediate electrode layer, and a first electrode layer are arranged on one side of the substrate so as to be aligned in a direction orthogonal to the direction in which the first and second node portions are aligned. Comprising a vibration drive unit and a vibration detection unit formed of one or more piezoelectric elements configured by laminating two piezoelectric thin film layers and an upper electrode layer,
The first piezoelectric thin film layer and the second piezoelectric thin film layer are polarized in opposite directions ,
The substrate includes an extension extending outward in the longitudinal direction beyond the first and second pair of support beams;
One or more thin film layers are formed as a balance weight on the one surface of the extension portion .   The substrate is made of a flexible resin substrate such as a silicon substrate, a glass substrate, a metal plate, or polyimide, or a composite substrate in which a flexible resin substrate is laminated on a metal plate. 3. The piezoelectric vibration type inertial sensor according to 1 or 2.   The piezoelectric vibration type inertial sensor according to claim 2, wherein the substrate is made of an insulating thin film or a sheet. The lower electrode layer is formed by including a metal thin film having a face-centered cubic lattice structure such as aluminum, silver, gold, copper, platinum, etc.
The piezoelectric thin film layer is composed of at least one of an aluminum nitride thin film, a gallium nitride thin film, an indium nitride thin film, a zinc sulfide thin film, a lithium niobate thin film, a zinc oxide thin film, and a lithium tantalate thin film, and a dipole The piezoelectric vibration type inertial sensor according to any one of claims 1 to 4, wherein the degree of orientation is 55% or more. The lower electrode layer is formed by including a metal thin film having a face-centered cubic lattice structure such as aluminum, silver, gold, copper, platinum, etc.
The intermediate electrode layer is formed of a metal thin film having a body-centered cubic lattice structure such as molybdenum,
Wherein the first and second piezoelectric thin film layer, an aluminum respectively nitride film, a gallium nitride thin film, an indium nitride thin film, a zinc sulfide thin film, one Izu Re of lithium niobate thin film, a zinc oxide thin film and lithium tantalate thin films 3. The piezoelectric vibration type inertial sensor according to claim 2, wherein the piezoelectric vibration type inertial sensor is formed of the above thin film and has a dipole orientation degree of 55% or more. The lower electrode layer of the vibration drive unit and the lower electrode layer of the vibration detection unit are continuously formed to form one common electrode layer,
2. The piezoelectric vibration type according to claim 1, wherein the piezoelectric thin film layer of the vibration driving unit and the piezoelectric thin film layer of the vibration detecting unit are continuously formed to form one common piezoelectric thin film layer. Inertial sensor. A pair of input electrodes for the vibration drive unit and a pair of output electrodes for the vibration detection unit are formed on the base,
The lower electrode layer and the upper electrode layer of the vibration drive unit and the pair of input electrodes are respectively formed on the two support beams selected from the first and second pair of support beams. Connected through
The lower electrode layer and the upper electrode layer of the vibration detector and the pair of output electrodes are respectively formed on two other support beams selected from the first and second pair of support beams. The piezoelectric vibration type inertial sensor according to claim 1, wherein the piezoelectric vibration type inertial sensor is connected via a lead wire. A first step of forming a vibration drive unit and a vibration detection unit on one side of the semiconductor substrate;
Etching is performed on the semiconductor substrate, and the substrate is arranged so as to surround the periphery of the substrate with a predetermined gap between the substrate having flexibility including the vibration driving unit and the vibration detecting unit, and the substrate. A base, a first pair of support beams for supporting the substrate with respect to the base at a first node when the substrate is flexibly vibrated, and a second node when the substrate is flexibly vibrated A second step of forming a sensor body integrally including a second pair of support beams for supporting the substrate with respect to the base body;
In the second step, an extension portion that extends outward in the longitudinal direction beyond the first and second pair of support beams is formed on the substrate,
In the first step, the first and second nodes are arranged in a direction orthogonal to a direction in which the first and second nodes are arranged on a surface region located between the first and second nodes on one side of the substrate. Forming a vibration drive unit and a vibration detection unit each including one or more piezoelectric elements each having a structure in which a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer are laminated, and the one side of the extension unit A method of manufacturing a piezoelectric vibration type inertial sensor, comprising forming one or more thin film layers as a balance weight thereon.

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