WO2019181455A1 - Autofocus drive mechanism using shape-memory-alloy thin film actuator array - Google Patents

Autofocus drive mechanism using shape-memory-alloy thin film actuator array Download PDF

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Publication number
WO2019181455A1
WO2019181455A1 PCT/JP2019/008340 JP2019008340W WO2019181455A1 WO 2019181455 A1 WO2019181455 A1 WO 2019181455A1 JP 2019008340 W JP2019008340 W JP 2019008340W WO 2019181455 A1 WO2019181455 A1 WO 2019181455A1
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Prior art keywords
thin film
alloy thin
shape memory
memory alloy
substrate
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PCT/JP2019/008340
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French (fr)
Japanese (ja)
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章 石田
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国立研究開発法人物質・材料研究機構
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Priority to JP2020508139A priority Critical patent/JP6986785B2/en
Publication of WO2019181455A1 publication Critical patent/WO2019181455A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
    • F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
    • F03G7/06—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
    • G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B17/00—Details of cameras or camera bodies; Accessories therefor
    • G03B17/02—Bodies
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B5/00—Adjustment of optical system relative to image or object surface other than for focusing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/02—Constructional features of telephone sets
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof

Definitions

  • the present invention relates to a drive mechanism for auto focus or camera shake correction of a camera module, particularly a mobile phone camera module.
  • VCMs voice coil motors
  • piezoelectric elements piezoelectric elements
  • shape memory alloy thin film actuators using MEMS Micro Electro Mechanical Systems
  • MEMS Micro Electro Mechanical Systems
  • bridge type diaphragm type
  • cantilever type The bridge type and diaphragm type have a large force for use in the tensile deformation mode, but the displacement is small, and the cantilever type is used in the bending deformation mode. Therefore, it is pointed out that the displacement is large but the force is weak (Non-patent Document 1).
  • Non-patent document 2 reports a walking robot, a transporter, or a gripper as a device using shape memory alloy thin film actuators in an array.
  • Non-Patent Document 3 The shape memory characteristics of the shape memory alloy thin film alone have been investigated in Non-Patent Document 3, and it has been reported that a Ti—Ni—Cu alloy thin film produced by sputtering exhibits characteristics superior to those of a Ti—Ni alloy thin film. Yes.
  • Patent Document 2 reports an example in which a bridge-type shape memory alloy thin film actuator is applied to an autofocus drive mechanism.
  • the shape memory alloy thin film actuator expands and contracts in a direction perpendicular to the optical axis, this displacement is reported.
  • a complicated moving mechanism is required to change the angle in the direction of the optical axis.
  • Patent Documents 3 and 4 disclose a mechanism in which a movable part is moved by a cantilever actuator that extends along two opposing sides of a movable part that is rectangular in plan view.
  • the cantilever actuator has a weak force, and the generated force decreases in inverse proportion to the cube of the length of the cantilever.
  • a 10 mm long cantilever generates only 1/1000 of a force compared to a 1 mm long cantilever.
  • reliability is lacking because it depends on the characteristics of several actuators, and the free end of the cantilever is in contact with the movable part at a point, so that design and assembly are difficult.
  • it is necessary to provide a separate stopper mechanism so as not to inadvertently deform the cantilever at room temperature.
  • Non-patent document 2 reports a walking robot, a transporter, or a gripper as a device that uses the shape memory alloy thin film actuator array for horizontal movement and gripping.
  • a bimorph actuator that uses only thermal strain as a bias force. It has been pointed out that since it becomes flat during heating (austenite phase) and curves at room temperature (martensite phase), the large shape recovery force generated during heating of the shape memory alloy cannot be used as a force for lifting an object.
  • the present invention solves the above-described problems, and is an autofocus drive mechanism that is extremely thin, highly responsive, large in generating force, simple in structure, easy to manufacture, and capable of correcting camera shake. And a camera unit using it.
  • the autofocus drive mechanism of the present invention employs the following configuration.
  • An actuator array substrate in which a plurality of shape memory alloy thin films whose fixed end side is fixed to the substrate and whose front end side is released from the substrate and warped are arranged in a plane on the substrate constitute an actuator array;
  • An autofocus drive mechanism comprising a housing that holds a structure in which the actuator array substrate, the plate, and the bias spring are stacked.
  • the shape memory alloy thin film is laminated with a lower layer thin film having a thermal expansion coefficient smaller than the thermal expansion coefficient of the shape memory alloy thin film, and the shape memory alloy thin film is in an austenite phase due to thermal strain after heat treatment.
  • the autofocus drive mechanism according to any one of [1] to [3], wherein the autofocus drive mechanism has a shape warped with respect to the substrate.
  • the autofocus drive mechanism according to [4], wherein the lower layer thin film having a thermal expansion coefficient smaller than that of the shape memory alloy thin film is a SiO 2 thin film.
  • a spacer is provided on the upper surface of the plate that supports the moving object, and the upper end of the spacer is in contact with the lower surface of the bias spring. 5].
  • the autofocus drive mechanism according to any one of [5]. [7] The autofocus drive mechanism according to any one of [1] to [5], wherein the bias spring is a second actuator array substrate having a configuration similar to that of the actuator array substrate. . [8] The autofocus drive mechanism according to any one of [1] to [7], wherein the substrate is a Si wafer substrate. [9] The shape memory alloy thin film is composed of Ti containing 50 atomic% or more and 55 atomic% or less of Ti, 10 atomic% or more and 20 atomic% or less of Cu, the balance being Ni and inevitable impurities. The autofocus drive mechanism according to any one of [1] to [8], which is a Ni—Cu alloy thin film.
  • the shape memory alloy thin film has a compositional element of Ti of 45 atomic% or more and less than 50 atomic%, atomic percentage of 10 + 1.6 ⁇ (50 ⁇ Ti atomic%) exceeding 20 + 1.6 ⁇ (50
  • the auto according to any one of [1] to [8], characterized in that it is a Ti—Ni—Cu alloy thin film in which Cu is equal to or less than (atomic% of Ti), and the balance is Ni and inevitable impurities. Focus drive mechanism.
  • the shape memory alloy thin film has Ti—50 atomic% to 55 atomic% Ti, 5 atomic% to 10 atomic% Cu, the balance being Ni and inevitable impurities.
  • the autofocus drive mechanism according to any one of [1] to [8], wherein the autofocus drive mechanism is a Ni—Cu alloy thin film.
  • the autofocus drive mechanism according to any one of [1] to [11], wherein the moving object is a lens or an image sensor.
  • the moving object is a lens
  • the substrate has an opening window for securing an optical path
  • the arrangement of the plurality of shape memory alloy thin films on the actuator array substrate surrounds the opening window.
  • the autofocus drive mechanism according to any one of [1] to [11], wherein the autofocus drive mechanism is disposed on the substrate at a substantially uniform density.
  • the autofocus driving mechanism according to any one of [1] to [13], wherein the shape memory alloy thin film is heated by means of heating the austenite phase and martensite phase of the shape memory alloy thin film.
  • a camera module configured to have a function of performing autofocus by adjusting a tissue ratio.
  • a function of performing autofocus by controlling the electrical resistance of the plurality of shape memory alloy thin films by passing a driving current from an autofocus control circuit to the plurality of shape memory alloy thin films.
  • the camera module according to [14] which is configured.
  • the camera is configured to have a camera shake correction function by energizing a drive current independently to each shape memory alloy thin film of the plurality of shape memory alloy thin films [14] to [17] ]
  • the camera module as described in any one of.
  • a camera-equipped mobile phone comprising the camera module according to any one of [14] to [18].
  • a plurality of shape memory alloy thin film actuators whose overall load applied to the plate that supports the moving object is shorter than the length of the side or diameter of the plate.
  • the overall load can be increased, and the autofocus drive mechanism can be easily assembled and the reliability can be improved.
  • the shape of the shape memory alloy thin film is warped with respect to the plane formed by the substrate during heating (austenite phase), and the plane formed by the substrate at room temperature (martensite phase).
  • a large shape recovery force due to reverse transformation during heating which is a feature of the shape memory alloy, can be used as a driving force for lifting (moving) the moving object.
  • the operating temperature of the autofocus drive mechanism can be set higher than the martensitic transformation end temperature of the shape memory alloy thin film.
  • the shape is easily formed by the thermal strain remaining between the shape memory alloy thin film and the lower layer thin film having a thermal expansion coefficient smaller than that of the shape memory alloy thin film.
  • the memory alloy thin film (austenite phase) can be warped with respect to the plane formed by the substrate.
  • the SiO 2 film can be used as a lower layer thin film having a thermal expansion coefficient smaller than that of the shape memory alloy thin film, and is insulated from the substrate. be able to.
  • the current applied to the shape memory alloy thin film constituting the actuator array substrate is controlled to set the spring constant of the bias spring to a low Young's modulus at room temperature and to a high Young's modulus at high temperature. By doing so, the stroke of the autofocus drive mechanism can be increased compared to the case where a bias spring having a constant spring constant is used.
  • the actuator array substrate described in [1] to [7] can be mass-produced at low cost by using a semiconductor process.
  • An array substrate can be produced.
  • the generated force is remarkably larger than that of the Ti—Ni—Cu alloy wire, and the sputtering is difficult to control the composition because the composition dependency of the characteristics is small.
  • the actuator array substrate using the shape memory alloy thin film exhibiting the above characteristics can be manufactured in large quantities at low cost.
  • an actuator array substrate using a shape memory alloy thin film having a transformation temperature higher than that of the thin film of the invention [10] having the above structure and excellent in reliability is manufactured. Can do.
  • an autofocus drive mechanism for a camera can be provided.
  • the autofocus drive mechanism according to [1] to [11] having the maximum generation force when the moving object is a lens can be obtained.
  • the shape memory alloy thin film can be easily heated, and a camera module with a simple structure can be provided.
  • a camera module capable of effective heating can be provided.
  • the moving object can be tilted from the vertical direction of the substrate by changing the height of the tip portion of each shape memory alloy thin film actuator from the substrate, thereby correcting camera shake. Can be provided.
  • the thickness of the camera-equipped mobile phone can be reduced.
  • FIG. 1A is a sectional view of one bimorph type cantilever type shape memory alloy thin film actuator formed on a substrate.
  • FIG. 1B is a plan view of the shape memory alloy thin film actuator of FIG.
  • FIG. 1C shows an actuator array substrate in which cantilever type shape memory alloy thin film actuators are arranged in parallel on the substrate.
  • FIG. 1 (d) shows an actuator array substrate in which cantilever-type shape memory alloy thin film actuators are annularly arranged on the substrate. It is an assembly drawing of an autofocus drive mechanism.
  • FIG. 2A is a diagram in which an actuator array substrate, a lens or a support plate for an image sensor and a bias spring (spring plate) are passed through alignment columns.
  • FIG. 1A is a sectional view of one bimorph type cantilever type shape memory alloy thin film actuator formed on a substrate.
  • FIG. 1B is a plan view of the shape memory alloy thin film actuator of FIG.
  • FIG. 1C shows an actuator array substrate in which cantilever type shape memory alloy
  • FIG. 2B shows an example of a spring plate.
  • FIG. 2C shows a structure in which the movable portion of the spring plate and the lens or the plate of the image sensor are joined to eliminate the alignment support.
  • FIG. 2D shows an example in which a flat spring plate is used by providing a protruding spacer on the upper surface of the support plate. It is a figure which shows the various usage forms of an actuator array board
  • 3 (a) shows a form in which the actuator array substrate of FIG. 2 (a) is turned upside down
  • FIG. 3 (b) shows a form having actuator arrays on both sides of the substrate
  • FIG. 3 (c) shows a plurality of actuator array substrates.
  • FIG. 3 (d) shows a form in which the second actuator array substrate is used as a bias spring.
  • FIG. 4A shows a process of forming a shape memory alloy thin film on a Si wafer substrate on which a SiO 2 film is formed by thermal oxidation, and a crystallization heat treatment.
  • FIG. 4B shows a shape using patterning by photoetching.
  • 4C shows a step of etching the memory alloy thin film
  • FIG. 4C shows a step of etching the SiO 2 film
  • FIG. 4D shows a step of isotropic etching of the Si wafer substrate.
  • FIG. 4A shows a process of forming a shape memory alloy thin film on a Si wafer substrate on which a SiO 2 film is formed by thermal oxidation, and a crystallization heat treatment.
  • FIG. 4B shows a shape using patterning by photoetching.
  • 4C shows a step of etching the memory alloy thin film
  • FIG. 4C shows a step of etching the SiO 2 film
  • FIG. 4D shows a step of isotropic etching of the Si
  • FIG. 5A shows a state in which a bimorph shape memory alloy thin film actuator array substrate in an unloaded state, a plate supporting a moving object, and a spring plate are stacked (when heated), and FIG. an initial load state of F B of chi B E B (when heated), FIG. 5 (c) (during heating) steady state in which the load F is load such as the weight of the lens, FIG. 5 (d) is a bimorph
  • the state (room temperature) in which the mold shape memory alloy thin film actuator is pressed onto the Si wafer substrate is shown.
  • the simulation result of the stroke and allowable load of the autofocus driving mechanism in which the shape of the bimorph shape memory alloy thin film actuator (the length of the actuator and the thickness of the shape memory alloy thin film and the SiO 2 film) is changed is shown.
  • FIGS. 1 to 7 of the accompanying drawings show a cantilever-type shape memory alloy thin film actuator 2 (here, a shape memory alloy thin film 3 and a thin film 4 having a smaller thermal expansion coefficient than that) formed on a substrate 1.
  • the shape of the shape memory alloy thin film actuator 2 is generally U-shaped as shown in FIG. However, it is not necessary to adhere to this shape when performing external heating with a heater or the like.
  • the thin film 4 on the side close to the substrate 1 among the thin films constituting the shape memory alloy thin film actuator 2 is also referred to as a “lower layer” for convenience. As shown in FIG.
  • the shape memory alloy thin film actuator 2 has a fixed end side (left side in FIG. 1A) fixed to the substrate 1 and a tip end side (right side in FIG. 1A) on the substrate. It is released from 1. Further, FIG. 1A shows a state in which the shape memory alloy thin film actuator 2 is warped with respect to the plane formed by the substrate 1 (the surface in the left-right direction in FIG. 1A).
  • the shape memory alloy thin film actuator 2 warped from the substrate 1 as shown in FIG. 1 (a)
  • a method using shape memory treatment or residual stress at the time of film formation is also conceivable.
  • the bimorph (two layers) is not essential, and may be a unimorph (one layer) as long as the shape memory alloy thin film 3 has a shape warped from the substrate 1.
  • a small cantilever type shape memory alloy thin film actuator 2 (hereinafter also referred to as “cantilever type actuator 2”) as shown in FIGS. 1A and 1B is a substrate.
  • 1 shows a plurality of actuator array substrates (FIG. 1C is a parallel arrangement, and FIG. 1D is an annular arrangement).
  • cantilever actuators 2 having the same size and different orientations are formed in pairs, but this is not necessarily a necessary condition. However, such a form is preferable because the movements in the horizontal direction cancel each other.
  • the assembly can be simplified as will be described later, and the operation reliability is improved. Can be improved.
  • each cantilever actuator 2 not only a movement in a direction perpendicular to the substrate 1 (autofocus mechanism) but also a movement tilted from the vertical direction (camera shake correction mechanism) is possible.
  • FIG. 2A is a diagram in which an autofocus drive mechanism is assembled using the actuator array substrate of FIG.
  • an actuator array substrate 7 a plate 9 (hereinafter also referred to as “plate 9”) that supports a moving object (such as a lens 8 or an image sensor), a spring plate (bias).
  • Spring 10 is stacked, and the case (housing) 12 holds the structure.
  • the actuator portion has only the thickness of the substrate 1 and the displacement amount of the cantilever actuator 2, and a drive mechanism having a thickness of 1 mm or less can be realized.
  • an alignment hole for example, a support hole as indicated by reference numeral 6 in FIGS.
  • the plate can be easily assembled by simply passing the plate through the columns 11a and 11b. Such assembling is easy because the plate 9 is supported in a plane by providing a plurality of contact points between the plate 9 and the cantilever actuator 2 using a large number of cantilever actuators 2, that is, equivalent to surface contact. By getting the effect of. Compared to Patent Documents 3 and 4 in which the free end of the cantilever is in contact with the movable part at a point, it is not necessary to accurately align the position of the contact.
  • the movable portion 14 inside the spring plate 10 as shown in FIG. 2B is joined to the plate 9 shown in FIG. 2C, and the spring plate 10 is fixed.
  • the frame 13 is fixed to the case 12, the movement of the lens 8 is limited to the vertical direction, so that even the alignment column can be omitted as shown in FIG.
  • a spring plate is used as a bias spring for applying a bias force, but a spring-like spring may be used.
  • the spring plate need not be limited to a downwardly bent shape as shown in FIG. 2A, and may be a flat shape.
  • the spring plate 10 is attached to the plate 9 at an angle, or a spacer 21 is provided between the plate 9 and the spring plate 10 as shown in FIG. By making the upper end portion of 21 come into contact with the lower surface of the spring plate 10, a force for pressing the plate 9 can be obtained.
  • the second actuator array substrate can be used as the bias spring.
  • FIG. 2A shows the minimum components necessary to realize the autofocus drive mechanism of the present invention.
  • an additional camera shake correction mechanism or Elements such as an image sensor, a heat dissipation plate made of Cu, wiring, and the like may be additionally inserted between the case 12, the actuator array substrate 7, the plate 9, the spring plate 10, and the like.
  • a heat dissipation plate By inserting a heat dissipation plate on the back side of the substrate 1, the cooling speed of the shape memory alloy thin film actuator 2 can be increased and the response speed can be increased.
  • the surface of the plate 9 that contacts the shape memory alloy thin film (the shape memory alloy thin film 3 constituting the cantilever actuator 2) may be coated so as to reduce the friction coefficient. Needs to be coated with an insulating film.
  • FIG. 3 shows various application forms of the actuator array substrate.
  • FIG. 3A is an example in which the actuator array substrate 7 of FIG. 2A is turned upside down. In this case, the lens 8 can be fixed to the actuator array substrate 7.
  • FIG. 3B shows an example in which an array of cantilever actuators 2a and 2b is formed on both surfaces of the substrate 1, whereby the amount of displacement of the lens 8 or the image sensor can be doubled.
  • FIG. 3C shows an example in which a plurality of actuator array substrates 7a, 7b, and 7c are stacked to increase the amount of displacement.
  • FIG. 3D shows an example in which the second actuator array substrate 7b is used as a bias spring instead of the spring plate (bias spring) 10 shown in FIG.
  • the stroke of the autofocus drive mechanism can be increased compared to the case where a bias spring having a constant spring constant is used.
  • the array of shape memory alloy thin film actuators 2 as shown in FIG. 1 can be manufactured by, for example, a semiconductor process.
  • the SiO 2 film 15 a is used as the lower layer film of the bimorph actuator, but an SiN film or the like can be produced by the same process and used as the lower layer film.
  • SiO 2 films 15a and 15b are formed on the Si wafer substrate 16 by thermal oxidation. The thickness of the SiO 2 film 15a can be changed by selecting an oxidation condition such as an oxidation time. Note that the SiO 2 film may be formed by other methods such as a CVD method.
  • the shape memory alloy thin film 3 is formed by sputtering on the Si wafer substrate 16 on which the SiO 2 film is formed by thermal oxidation.
  • the thickness of the shape memory alloy thin film 3 can be changed according to sputtering conditions such as film formation time. Since the thin film after film formation is amorphous, the thin film is crystallized by performing heat treatment at, for example, 500 ° C. or higher. The thermal strain remaining after the heat treatment plays an important role in changing the shape memory alloy thin film actuator 2 (the shape memory alloy thin film 3 and the SiO 2 film 15a) to a shape warped from the Si wafer substrate 16 (FIG. 4D). reference).
  • Shape memory alloy thin films include alloys showing shape memory effects such as Ti—Ni, Ti—Ni—Cu, Ti—Ni—Pd, Ti—Ni—Hf, Ti—Ni—Zr, Cu—Al—Ni alloys. Any thin film may be used, but a Ti—Ni—Cu alloy thin film containing 50 atomic% to 55 atomic% Ti and 5 atomic% to 10 atomic% Cu, 50 atomic% to 55 atomic% Ti Ti-Ni-Cu alloy thin film containing more than 10 atomic% and 20 atomic% or less of Cu, or 45 atomic% or more and less than 50 atomic% of Ti and atomic% of 10 + 1.6 ⁇ (50-Ti atomic% It is preferable to use a Ti—Ni—Cu alloy thin film containing Cu exceeding 20 + 1.6 ⁇ (50-Ti atomic%) and less.
  • an actuator array using a shape memory alloy thin film having a transformation temperature higher than that of a Ti—Ni alloy, a small temperature hysteresis, a large generated force, and excellent responsiveness can be manufactured. Can do.
  • a Ti—Ni—Cu alloy thin film containing 50 atomic% or more and 55 atomic% or less of Ti and more than 10 atomic% and 20 atomic% or less of Cu or 45 atomic% or more and less than 50 atomic% of Ti and atoms It is preferable to use a Ti—Ni—Cu alloy thin film containing 10 + 1.6 ⁇ (50-Ti atomic%) and 20 + 1.6 ⁇ (50-Ti atomic%) or less of Cu. According to the alloy thin film having such a composition, the generated force is remarkably larger than that of the Ti—Ni—Cu alloy wire, and stable characteristics (high force, high) are obtained even in sputtering in which composition control of properties is small and composition control is difficult. An actuator array using a shape memory alloy thin film exhibiting responsiveness and high transformation temperature can be manufactured in large quantities at low cost.
  • the transformation temperature is higher.
  • An actuator array (non-patent document 3) using a shape memory alloy thin film having excellent reliability can be manufactured.
  • a negative resist is spin-coated on the shape memory alloy thin film 3 and patterning is performed by photoetching. Using the resist as a mask, unnecessary portions of the shape memory alloy thin film 3 are removed by etching with diluted HF / HNO 3 , or electrolytically etched with a sulfuric acid / methanol mixed solution or the like.
  • FIG. 4C the underlying SiO 2 film 15a is etched with buffered hydrofluoric acid.
  • the Si wafer substrate 16 under the SiO 2 film 15a is further isotropically etched using XeF 2 gas to thereby form two layers of the shape memory alloy thin film 3 and the SiO 2 film 15a.
  • the film shape memory alloy thin film actuator 2 is released from the Si wafer substrate 16.
  • a material having a smaller thermal expansion coefficient than the shape memory alloy thin film for example, SiO 2
  • SiO 2 as the lower layer of the shape memory alloy thin film.
  • the semiconductor process shown in FIG. 4 is an example of a method for producing an array of shape memory alloy thin film actuators 2, and the configuration of the shape memory alloy thin film actuator as shown in FIGS. If the structure of the actuator array substrate as shown in c) and (d) can be realized, it is not necessary to follow the process of FIG. 4 and it is not necessary to be involved in a semiconductor process using Si. For example, by using a metal, resin, or glass substrate as the actuator array substrate, the manufacturing cost of the autofocus drive mechanism can be reduced.
  • FIG. 5 shows the driving principle of the autofocus driving mechanism according to the present invention and the simulation model used for the design.
  • FIG. 5A shows an actuator array substrate (substrate 1 and shape memory alloy thin film actuator 2) on the bottom surface 20 of the case (housing) during high temperature heating (when the Ti—Ni—Cu shape memory alloy thin film 18 is in the austenite phase).
  • a plate 9 hereinafter also referred to as “plate 9”
  • E A and E B are spring constants
  • ⁇ T is the height of the shape memory alloy thin film actuator 2 from the surface of the substrate 1.
  • 5 (b) shows a state in which the spring plate 10 in the shape memory alloy thin film actuator 2 gave a force F B.
  • ⁇ B is the vertical contraction amount of the spring plate 10 (displacement amount of the case upper lid 19)
  • ⁇ B is the vertical contraction amount of the shape memory alloy thin film actuator 2 (displacement amount of the case bottom surface 20).
  • FIG. 5C shows a state when a force F (for example, a lens weight) is further applied to the shape memory alloy thin film actuator 2 from the outside.
  • ⁇ W is an amount of the shape memory alloy thin film actuator 2 contracted in the vertical direction by the external force F
  • ⁇ differs between high temperature ( ⁇ H ) and low temperature ( ⁇ L ), and this difference becomes the stroke of the plate 9.
  • ⁇ H high temperature
  • ⁇ L low temperature
  • the substrate 1 also has an effect of preventing unnecessary deformation and preventing introduction of plastic deformation into the Ti—Ni—Cu shape memory alloy thin film 18. That is, the function can be substituted by the substrate 1 without making a separate stopper in the drive mechanism unit.
  • FIG. 6 shows the result of simulation using the model of FIG.
  • the shape of the cantilever-type shape memory alloy thin film actuator (actuator length and shape memory alloy thin film and SiO 2 film thickness) constituting the array
  • an auto that can tolerate a stroke of 100 to 600 ⁇ m and a load exceeding 14 gf A focus drive mechanism can be manufactured.
  • ⁇ L ⁇ 0 ⁇ H and by using a part of the martensitic transformation of the shape memory alloy thin film, it is possible to expect an increase in operating temperature.
  • the actuator shape and the load by the lens are the same, but in the example of No.
  • the shape memory alloy thin film actuator is warped in the austenite phase during heating and becomes flat in the martensite phase during cooling. It is necessary to use with a large load, and when the load by the lens is small, it is necessary to supplement the load with a bias spring.
  • the lens 8 is a case where the lens is supported by two long bimorph actuators installed so as to extend along two opposing sides of the movable part as described in Patent Document 3, but ⁇ L ( -135582 ⁇ m) and ⁇ H (300 ⁇ m), the shape memory alloy thin film that can be used for driving the lens (moving object) has very little martensitic transformation, and although a stroke of 300 ⁇ m can be obtained, the usable load is 0. It can be seen that it is very small as 02 gf.
  • FIG. 7 is a configuration diagram of the actuator array substrate 7 used when the simulation of FIG. 6 is performed. Assuming that an opening window 5 for a 6 mm ⁇ lens is opened on a 12 mm ⁇ 12 mm substrate as shown in FIG. 7A, one cell is 1.2 mm ⁇ 1.2 mm and a total of 64 cells is arranged. Can be arranged. That is, when the bimorph shape memory alloy thin film actuator 2 shown in FIG. 5 has a width of 100 ⁇ m and a length of 1000 ⁇ m, 10 pieces can be arranged per square (1.2 mm ⁇ 1.2 mm) as shown in FIG. , 64 ⁇ 640 in total can be produced. When the moving object is an image sensor, there is no need to make a hole in the center. In that case, 1000 actuators can be mounted, and the allowable load shown in FIG. become.
  • the lens position can be changed in a direction perpendicular to the substrate (autofocus function). Furthermore, if each actuator is moved independently, it can also be tilted from the vertical direction (camera shake correction mechanism).

Abstract

The present invention provides an ultrathin autofocus drive mechanism that allows a camera module with a lower height to be achieved, facilitates assembly, and corrects for camera shake. According to the present invention, with respect to an actuator array substrate 7 which comprises a substrate 1 having an array of shape-memory-alloy thin film actuators 2 (a plurality of planarly arrayed actuators) arching therefrom, the application of a biasing force by a leaf spring 10 to the actuator array substrate 7 allows for perpendicular movement, relative to the substrate 1, of a plate 9 for supporting the object to be moved (autofocus mechanism); in addition, it is possible to tilt the plate 9 relative to the direction perpendicular to the substrate 1 by moving individual actuators 2 independently (camera-shake correction mechanism).

Description

形状記憶合金薄膜アクチュエータアレイによるオートフォーカス駆動機構Autofocus drive mechanism by shape memory alloy thin film actuator array
　本発明は、カメラモジュール、特に携帯電話用カメラモジュールのオートフォーカスあるいは手振れ補正の駆動機構に関する。 The present invention relates to a drive mechanism for auto focus or camera shake correction of a camera module, particularly a mobile phone camera module.
　現在流通しているオートフォーカスあるいは手振れ補正の駆動機構の主流はＶＣＭ（ボイスコイルモーター）や圧電素子であり、携帯電話の薄型化を進める上でこれらの駆動機構のさらなる小型、軽量化に対する要望は大きくなっている（特許文献１）。 The mainstream of autofocus or camera shake correction drive mechanisms currently in circulation are VCMs (voice coil motors) and piezoelectric elements, and there is a demand for further miniaturization and weight reduction of these drive mechanisms as mobile phones become thinner. It is increasing (Patent Document 1).
　一方、ＭＥＭＳ（Ｍｉｃｒｏ　Ｅｌｅｃｔｒｏ　Ｍｅｃｈａｎｉｃａｌ　Ｓｙｓｔｅｍｓ：微小電気機械システム）技術を使った形状記憶合金薄膜アクチュエータは小型で強力なアクチュエータとして期待されている。アクチュエータの形態としては、ブリッジ型、ダイヤフラム型、カンチレバー型があり、ブリッジ型とダイヤフラム型は引っ張り変形モードで使うために力は大きいが、変位量が小さく、また、カンチレバー型は曲げ変形モードで使うために変位量は大きいが、力が弱いことが指摘されている（非特許文献１）。 On the other hand, shape memory alloy thin film actuators using MEMS (Micro Electro Mechanical Systems) technology are expected as small and powerful actuators. There are two types of actuators: bridge type, diaphragm type, and cantilever type. The bridge type and diaphragm type have a large force for use in the tensile deformation mode, but the displacement is small, and the cantilever type is used in the bending deformation mode. Therefore, it is pointed out that the displacement is large but the force is weak (Non-patent Document 1).
　オートフォーカス駆動機構に上記形状記憶合金薄膜アクチュエータを使った例としては、ブリッジ型が特許文献２で、カンチレバー型が特許文献３と４で知られている。
　また、形状記憶合金薄膜アクチュエータをアレイにして使ったデバイスとしては、歩行ロボットや搬送機あるいはグリッパが非特許文献２で報告されている。 As an example of using the shape memory alloy thin film actuator for the autofocus drive mechanism, the bridge type is known from Patent Document 2, and the cantilever type is known from Patent Documents 3 and 4.
Non-patent document 2 reports a walking robot, a transporter, or a gripper as a device using shape memory alloy thin film actuators in an array.
　形状記憶合金薄膜単体の形状記憶特性は非特許文献３で調べられており、スパッタリングで作製したＴｉ－Ｎｉ－Ｃｕ合金薄膜は、Ｔｉ－Ｎｉ合金薄膜よりも優れた特性を示すことが報告されている。 The shape memory characteristics of the shape memory alloy thin film alone have been investigated in Non-Patent Document 3, and it has been reported that a Ti—Ni—Cu alloy thin film produced by sputtering exhibits characteristics superior to those of a Ti—Ni alloy thin film. Yes.
特開２０１３－２５４１８４号公報JP 2013-254184 A 特開２００９－１９６０６０号公報JP 2009-196060 A 特開２０１１－１０９８５３号公報JP 2011-109853 A 特開２００９－８９３０６号公報JP 2009-89306 A
　携帯電話などのカメラモジュールでは低背化が望まれている。しかし、圧電素子あるいはＶＣＭ（ボイスコイルモーター）を使った駆動機構を厚さ１ｍｍ以下にすることは、構造の複雑さを考えると困難である。 ● Lowering the height is desired for camera modules such as mobile phones. However, it is difficult to reduce the thickness of a drive mechanism using a piezoelectric element or VCM (voice coil motor) to 1 mm or less in view of the complexity of the structure.
　特許文献２では、ブリッジ型形状記憶合金薄膜アクチュエータをオートフォーカス駆動機構に適用した例が報告されているが、ここでは形状記憶合金薄膜アクチュエータが光軸に垂直な方向に伸縮するために、この変位を光軸方向に変えるための複雑な移動機構を必要としている。 Patent Document 2 reports an example in which a bridge-type shape memory alloy thin film actuator is applied to an autofocus drive mechanism. Here, since the shape memory alloy thin film actuator expands and contracts in a direction perpendicular to the optical axis, this displacement is reported. A complicated moving mechanism is required to change the angle in the direction of the optical axis.
　一方、特許文献３と４では、平面視矩形の可動部品の対向する２辺に沿って延びて配置されたカンチレバー型アクチュエータで可動部品を移動させる機構が開示されている。しかし、カンチレバー型アクチュエータは力が弱いことが知られており、その発生力はカンチレバーの長さの３乗に反比例して減少する。たとえば、１０ｍｍの長さのカンチレバーは１ｍｍの長さのカンチレバーに比べて１／１０００の力しか発生しない。さらに、特許文献３及び４の形態では数本のアクチュエータの特性に左右されるために信頼性を欠き、カンチレバーの自由端が可動部品と点で接するために設計や組み立てが難しい。加えて、室温時にカンチレバーに不用意な変形を与えないように別途、ストッパの機構を設ける必要がある。 On the other hand, Patent Documents 3 and 4 disclose a mechanism in which a movable part is moved by a cantilever actuator that extends along two opposing sides of a movable part that is rectangular in plan view. However, it is known that the cantilever actuator has a weak force, and the generated force decreases in inverse proportion to the cube of the length of the cantilever. For example, a 10 mm long cantilever generates only 1/1000 of a force compared to a 1 mm long cantilever. Further, in the forms of Patent Documents 3 and 4, reliability is lacking because it depends on the characteristics of several actuators, and the free end of the cantilever is in contact with the movable part at a point, so that design and assembly are difficult. In addition, it is necessary to provide a separate stopper mechanism so as not to inadvertently deform the cantilever at room temperature.
　形状記憶合金薄膜アクチュエータアレイを水平移動や把持に使ったデバイスとしては、非特許文献２で歩行ロボットや搬送機あるいはグリッパが報告されているが、熱ひずみのみをバイアス力としたバイモルフ型アクチュエータでは、加熱時（オーステナイト相）に平坦になり、室温（マルテンサイト相）で湾曲するために、形状記憶合金の加熱時に発生する大きい形状回復力を物を持ち上げる力として利用できないことが指摘されている。 Non-patent document 2 reports a walking robot, a transporter, or a gripper as a device that uses the shape memory alloy thin film actuator array for horizontal movement and gripping. However, in a bimorph actuator that uses only thermal strain as a bias force, It has been pointed out that since it becomes flat during heating (austenite phase) and curves at room temperature (martensite phase), the large shape recovery force generated during heating of the shape memory alloy cannot be used as a force for lifting an object.
　本発明は上述の課題を解決したものであり、極薄型で、高応答性かつ発生力が大きく、構造がシンプルなために製造が容易で信頼性の高い、手振れ補正も可能なオートフォーカス駆動機構とそれを使ったカメラユニットを提供する。 The present invention solves the above-described problems, and is an autofocus drive mechanism that is extremely thin, highly responsive, large in generating force, simple in structure, easy to manufacture, and capable of correcting camera shake. And a camera unit using it.
　上記目的を達成するために、本発明のオートフォーカス駆動機構は以下の構成を採用した。
［１］　固定端側が基板に固定され、先端側が基板から解放されて反り上がった複数の形状記憶合金薄膜が前記基板上で面状に並べられてアクチュエータアレイを構成しているアクチュエータアレイ基板と、
　移動対象物を支持するプレートと、
　前記複数の形状記憶合金薄膜が、オーステナイト相で前記基板のなす平面に対して反り上がった形状となり、マルテンサイト相で前記基板のなす平面に対して大略平坦となるようなバイアス力を与えるバイアスばねを備え、
　前記アクチュエータアレイ基板、前記プレート、および前記バイアスばねが積層された構造を保持する筐体を備えることを特徴とするオートフォーカス駆動機構。
[２]　室温時に前記対象物を支持するプレートの移動が前記アクチュエータアレイ基板の基板によって停止することによって、形状記憶合金薄膜の変態ひずみを越えた余分な塑性変形を防ぐことを特徴とする[１]に記載のオートフォーカス駆動機構。
[３]　前記対象物を支持するプレートの移動が前記形状記憶合金薄膜のマルテンサイト変態終了温度よりも高い温度で前記アクチュエータアレイ基板の基板によって停止することを特徴とする［２］に記載のオートフォーカス駆動機構。 In order to achieve the above object, the autofocus drive mechanism of the present invention employs the following configuration.
[1] An actuator array substrate in which a plurality of shape memory alloy thin films whose fixed end side is fixed to the substrate and whose front end side is released from the substrate and warped are arranged in a plane on the substrate constitute an actuator array;
A plate that supports the moving object;
A bias spring that applies a biasing force so that the plurality of shape memory alloy thin films are warped with respect to the plane formed by the substrate in the austenite phase and are substantially flat with respect to the plane formed by the substrate in the martensite phase. With
An autofocus drive mechanism comprising a housing that holds a structure in which the actuator array substrate, the plate, and the bias spring are stacked.
[2] The movement of the plate supporting the object at room temperature is stopped by the substrate of the actuator array substrate, thereby preventing excessive plastic deformation exceeding the transformation strain of the shape memory alloy thin film [1] The autofocus drive mechanism described in the above.
[3] The auto according to [2], wherein the movement of the plate supporting the object is stopped by the substrate of the actuator array substrate at a temperature higher than a martensitic transformation end temperature of the shape memory alloy thin film. Focus drive mechanism.
［４］　前記形状記憶合金薄膜が当該形状記憶合金薄膜の熱膨張係数よりも小さな熱膨張係数を有する下層の薄膜と積層され、熱処理後の熱ひずみによって、当該形状記憶合金薄膜がオーステナイト相で前記基板に対して反り上がった形状とされたことを特徴とする［１］乃至［３］のいずれか一項に記載のオートフォーカス駆動機構。
［５］　前記形状記憶合金薄膜の熱膨張係数よりも小さな熱膨張係数を有する下層の薄膜は、ＳｉＯ２薄膜であることを特徴とする［４］に記載のオートフォーカス駆動機構。
［６］　前記移動対象物を支持するプレートの上面にスペーサーが突設されており、当該スペーサーの上端部が前記バイアスばねの下面に接するように構成されたことを特徴とする［１］乃至［５］のいずれか一項に記載のオートフォーカス駆動機構。
［７］　前記バイアスばねが、前記アクチュエータアレイ基板と同様の構成を有する第２のアクチュエータアレイ基板であることを特徴とする［１］乃至［５］のいずれか一項に記載のオートフォーカス駆動機構。
［８］　前記基板は、Ｓｉウエハ基板であることを特徴とする［１］乃至［７］のいずれか一項に記載のオートフォーカス駆動機構。
［９］　前記形状記憶合金薄膜は、組成元素を、５０原子％以上で５５原子％以下のＴｉ、１０原子％を超えて２０原子％以下のＣｕ、残部をＮｉおよび不可避的不純物とする、Ｔｉ－Ｎｉ－Ｃｕ合金薄膜であることを特徴とする［１］乃至［８]のいずれか一項に記載のオートフォーカス駆動機構。
［１０］　前記形状記憶合金薄膜は、組成元素を、４５原子％以上で５０原子％未満のＴｉ、原子％で１０＋１．６×（５０－Ｔｉの原子％）を超えて２０＋１．６×（５０－Ｔｉの原子％）以下のＣｕ、残部をＮｉおよび不可避的不純物とする、Ｔｉ－Ｎｉ－Ｃｕ合金薄膜であることを特徴とする［１］乃至［８]のいずれか一項に記載のオートフォーカス駆動機構。
［１１］　前記形状記憶合金薄膜は、組成元素を、５０原子％以上で５５原子％以下のＴｉ、５原子％以上で１０原子％以下のＣｕ、残部をＮｉおよび不可避的不純物とする、Ｔｉ－Ｎｉ－Ｃｕ合金薄膜であることを特徴とする［１］乃至［８]のいずれか一項に記載のオートフォーカス駆動機構。 [4] The shape memory alloy thin film is laminated with a lower layer thin film having a thermal expansion coefficient smaller than the thermal expansion coefficient of the shape memory alloy thin film, and the shape memory alloy thin film is in an austenite phase due to thermal strain after heat treatment. The autofocus drive mechanism according to any one of [1] to [3], wherein the autofocus drive mechanism has a shape warped with respect to the substrate.
[5] The autofocus drive mechanism according to [4], wherein the lower layer thin film having a thermal expansion coefficient smaller than that of the shape memory alloy thin film is a SiO 2 thin film.
[6] A spacer is provided on the upper surface of the plate that supports the moving object, and the upper end of the spacer is in contact with the lower surface of the bias spring. 5]. The autofocus drive mechanism according to any one of [5].
[7] The autofocus drive mechanism according to any one of [1] to [5], wherein the bias spring is a second actuator array substrate having a configuration similar to that of the actuator array substrate. .
[8] The autofocus drive mechanism according to any one of [1] to [7], wherein the substrate is a Si wafer substrate.
[9] The shape memory alloy thin film is composed of Ti containing 50 atomic% or more and 55 atomic% or less of Ti, 10 atomic% or more and 20 atomic% or less of Cu, the balance being Ni and inevitable impurities. The autofocus drive mechanism according to any one of [1] to [8], which is a Ni—Cu alloy thin film.
[10] The shape memory alloy thin film has a compositional element of Ti of 45 atomic% or more and less than 50 atomic%, atomic percentage of 10 + 1.6 × (50−Ti atomic%) exceeding 20 + 1.6 × (50 The auto according to any one of [1] to [8], characterized in that it is a Ti—Ni—Cu alloy thin film in which Cu is equal to or less than (atomic% of Ti), and the balance is Ni and inevitable impurities. Focus drive mechanism.
[11] The shape memory alloy thin film has Ti—50 atomic% to 55 atomic% Ti, 5 atomic% to 10 atomic% Cu, the balance being Ni and inevitable impurities. The autofocus drive mechanism according to any one of [1] to [8], wherein the autofocus drive mechanism is a Ni—Cu alloy thin film.
［１２］　前記移動対象物は、レンズ又は撮像素子であることを特徴とする［１］乃至［１１］に記載のオートフォーカス駆動機構。
［１３］　前記移動対象物はレンズであり、前記基板は光路確保のための開口窓を有し、前記アクチュエータアレイ基板における複数の形状記憶合金薄膜の配置は、前記開口窓を囲うように、前記基板に大略均一な密度で配置されていることを特徴とする［１］乃至［１１］のいずれか一項に記載のオートフォーカス駆動機構。 [12] The autofocus drive mechanism according to any one of [1] to [11], wherein the moving object is a lens or an image sensor.
[13] The moving object is a lens, the substrate has an opening window for securing an optical path, and the arrangement of the plurality of shape memory alloy thin films on the actuator array substrate surrounds the opening window. The autofocus drive mechanism according to any one of [1] to [11], wherein the autofocus drive mechanism is disposed on the substrate at a substantially uniform density.
[１４]　［１］乃至［１３］のいずれか一項に記載のオートフォーカス駆動機構を有し、前記形状記憶合金薄膜を加熱する手段によって、当該形状記憶合金薄膜のオーステナイト相とマルテンサイト相の組織割合が調整されてオートフォーカスを行う機能を具備するように構成したことを特徴とするカメラモジュール。
[１５]　オートフォーカス制御回路からの駆動電流を前記複数の形状記憶合金薄膜に通電することにより、前記複数の形状記憶合金薄膜の電気抵抗を制御して、オートフォーカスを行う機能を具備するように構成したことを特徴とする［１４］に記載のカメラモジュール。
[１６]　前記形状記憶合金薄膜は、固定端側の一端から先端側を経由して前記固定端側の他端に通電するように構成されたことを特徴とする[１５]に記載のカメラモジュール。
[１７]　前記加熱手段は、前記形状記憶合金薄膜の周囲に形成された電熱導体であることを特徴とする[１４]に記載のカメラモジュール。
[１８]　駆動電流を前記複数の形状記憶合金薄膜の個々の形状記憶合金薄膜に独立して通電することにより、手振れ補正機能を具備するように構成したことを特徴とする［１４］乃至［１７］のいずれか一項に記載のカメラモジュール。
[１９]　［１４］乃至［１８］のいずれか一項に記載のカメラモジュールを搭載したことを特徴とするカメラ付き携帯電話。 [14] The autofocus driving mechanism according to any one of [1] to [13], wherein the shape memory alloy thin film is heated by means of heating the austenite phase and martensite phase of the shape memory alloy thin film. A camera module configured to have a function of performing autofocus by adjusting a tissue ratio.
[15] A function of performing autofocus by controlling the electrical resistance of the plurality of shape memory alloy thin films by passing a driving current from an autofocus control circuit to the plurality of shape memory alloy thin films. The camera module according to [14], which is configured.
[16] The camera module according to [15], wherein the shape memory alloy thin film is configured to energize from one end on the fixed end side to the other end on the fixed end side via the tip end side. .
[17] The camera module according to [14], wherein the heating means is an electric heating conductor formed around the shape memory alloy thin film.
[18] The camera is configured to have a camera shake correction function by energizing a drive current independently to each shape memory alloy thin film of the plurality of shape memory alloy thin films [14] to [17] ] The camera module as described in any one of.
[19] A camera-equipped mobile phone comprising the camera module according to any one of [14] to [18].
　このように構成した発明［１］によれば、移動対象物を支持するプレートに負荷される全体の荷重を、当該プレートの辺もしくは径の長さよりも長さの短い複数の形状記憶合金薄膜アクチュエータで面状に分散して支えるために全体の負荷荷重を増やすことができ、オートフォーカス駆動機構の組み立ても容易で信頼性も向上する。また、バイアスばねを用いることによって、形状記憶合金薄膜の形状を、加熱時（オーステナイト相）に基板のなす平面に対して反り上がった形状とし、室温時（マルテンサイト相）に基板のなす平面に対して大略平坦とすることができるので、形状記憶合金の特徴である加熱時の逆変態による大きい形状回復力を移動対象物を持ち上げる（移動させる）駆動力として利用できる。 According to the invention [1] configured as described above, a plurality of shape memory alloy thin film actuators whose overall load applied to the plate that supports the moving object is shorter than the length of the side or diameter of the plate. In order to disperse and support in a plane, the overall load can be increased, and the autofocus drive mechanism can be easily assembled and the reliability can be improved. In addition, by using a bias spring, the shape of the shape memory alloy thin film is warped with respect to the plane formed by the substrate during heating (austenite phase), and the plane formed by the substrate at room temperature (martensite phase). On the other hand, since it can be made substantially flat, a large shape recovery force due to reverse transformation during heating, which is a feature of the shape memory alloy, can be used as a driving force for lifting (moving) the moving object.
　上記の構成を有する発明[２]によれば、別途、形状記憶合金薄膜の余分な塑性変形を防ぐためのストッパを設ける必要がなく、オートフォーカス駆動機構の構造を簡単にできる。
　上記の構成を有する発明[３]によれば、オートフォーカス駆動機構の作動温度を形状記憶合金薄膜のマルテンサイト変態終了温度よりも高く設定できる。 According to the invention [2] having the above-described configuration, it is not necessary to separately provide a stopper for preventing excessive plastic deformation of the shape memory alloy thin film, and the structure of the autofocus drive mechanism can be simplified.
According to the invention [3] having the above configuration, the operating temperature of the autofocus drive mechanism can be set higher than the martensitic transformation end temperature of the shape memory alloy thin film.
　上記の構成を有する発明［４］によれば、形状記憶合金薄膜と当該形状記憶合金薄膜の熱膨張係数よりも小さな熱膨張係数を有する下層の薄膜の間に残留した熱ひずみによって、容易に形状記憶合金薄膜（オーステナイト相）を基板のなす平面に対して反り上がった形状にできる。
　上記の構成を有する発明［５］によれば、ＳｉＯ２膜を形状記憶合金薄膜の熱膨張係数よりも小さな熱膨張係数を有する下層の薄膜として利用でき、また、基板との間の絶縁を図ることができる。 According to the invention [4] having the above configuration, the shape is easily formed by the thermal strain remaining between the shape memory alloy thin film and the lower layer thin film having a thermal expansion coefficient smaller than that of the shape memory alloy thin film. The memory alloy thin film (austenite phase) can be warped with respect to the plane formed by the substrate.
According to the invention [5] having the above-described configuration, the SiO 2 film can be used as a lower layer thin film having a thermal expansion coefficient smaller than that of the shape memory alloy thin film, and is insulated from the substrate. be able to.
　上記の構成を有する発明［６］によれば、フラットな形状を有するバイアスばねを用いて、移動対象物を支持するプレートを下向きに押さえつける力を得ることができる。
　上記の構成を有する発明［７］によれば、アクチュエータアレイ基板を構成する形状記憶合金薄膜に通電する電流を制御してバイアスばねのばね定数を室温で低ヤング率、高温で高ヤング率に設定することにより、ばね定数一定のバイアスばねを使った場合に比べてオートフォーカス駆動機構のストロークを増加させることができる。 According to the invention [6] having the above-described configuration, it is possible to obtain a force for pressing the plate supporting the moving object downward using the bias spring having a flat shape.
According to the invention [7] having the above configuration, the current applied to the shape memory alloy thin film constituting the actuator array substrate is controlled to set the spring constant of the bias spring to a low Young's modulus at room temperature and to a high Young's modulus at high temperature. By doing so, the stroke of the autofocus drive mechanism can be increased compared to the case where a bias spring having a constant spring constant is used.
　上記の構成を有する発明［８］によれば、半導体プロセスを利用することにより、［１］乃至［７］に記載のアクチュエータアレイ基板を安価に大量生産することができる。 According to the invention [8] having the above configuration, the actuator array substrate described in [1] to [7] can be mass-produced at low cost by using a semiconductor process.
　上記の構成を有する発明［９］乃至［１１］によれば、Ｔｉ－Ｎｉ合金より変態温度が高くて温度ヒステリシスが小さく、発生力が大きくて応答性に優れた形状記憶合金薄膜を使ったアクチュエータアレイ基板を作製することができる。 According to the inventions [9] to [11] having the above-described configuration, an actuator using a shape memory alloy thin film having a transformation temperature higher than that of a Ti—Ni alloy, a lower temperature hysteresis, a larger generated force, and an excellent response. An array substrate can be produced.
　上記の構成を有する発明［９］と［１０］によれば、Ｔｉ－Ｎｉ－Ｃｕ合金ワイヤよりも発生力が格段に大きく、また特性の組成依存性が小さくて組成制御が難しいスパッタリングにおいても安定した特性（大きい発生力、高い応答性、高い変態温度）を示す形状記憶合金薄膜を使ったアクチュエータアレイ基板を安価で大量に製造することができる。 According to the inventions [9] and [10] having the above-described configuration, the generated force is remarkably larger than that of the Ti—Ni—Cu alloy wire, and the sputtering is difficult to control the composition because the composition dependency of the characteristics is small. The actuator array substrate using the shape memory alloy thin film exhibiting the above characteristics (large generation force, high responsiveness, high transformation temperature) can be manufactured in large quantities at low cost.
　上記の構成を有する発明［９］によれば、上記の構成を有する発明［１０］の薄膜よりも変態温度が高く、信頼性に優れた形状記憶合金薄膜を使ったアクチュエータアレイ基板を製造することができる。 According to the invention [9] having the above structure, an actuator array substrate using a shape memory alloy thin film having a transformation temperature higher than that of the thin film of the invention [10] having the above structure and excellent in reliability is manufactured. Can do.
　上記の構成を有する発明［１２］によれば、カメラ用のオートフォーカス駆動機構を提供できる。 According to the invention [12] having the above configuration, an autofocus drive mechanism for a camera can be provided.
　上記の構成を有する発明［１３］によれば、移動対象物がレンズの場合に最大の発生力を有する［１］乃至[１１]に記載のオートフォーカス駆動機構が得られる。 According to the invention [13] having the above configuration, the autofocus drive mechanism according to [1] to [11] having the maximum generation force when the moving object is a lens can be obtained.
　上記の構成を有する発明[１４]によれば、移動対象物の位置を精密に制御できるカメラモジュールを提供できる。 According to the invention [14] having the above configuration, it is possible to provide a camera module capable of precisely controlling the position of the moving object.
　上記の構成を有する発明[１５]によれば、オートフォーカス制御回路を利用してオートフォーカス位置を精密に制御するカメラモジュールを提供できる。 According to the invention [15] having the above-described configuration, it is possible to provide a camera module that precisely controls the autofocus position using the autofocus control circuit.
　上記の構成を有する発明[１６]によれば、容易に形状記憶合金薄膜を加熱できて、簡単な構造のカメラモジュールを提供できる。 According to the invention [16] having the above-described configuration, the shape memory alloy thin film can be easily heated, and a camera module with a simple structure can be provided.
　上記の構成を有する発明[１７]によれば、効果的な加熱が可能なカメラモジュールを提供できる。 According to the invention [17] having the above configuration, a camera module capable of effective heating can be provided.
　上記の構成を有する発明[１８]によれば、個々の形状記憶合金薄膜アクチュエータの先端部の基板からの高さを変えることで、移動対象物を基板の垂直方向から傾けることができて手振れ補正を具備したカメラモジュールを提供できる。 According to the invention [18] having the above-described configuration, the moving object can be tilted from the vertical direction of the substrate by changing the height of the tip portion of each shape memory alloy thin film actuator from the substrate, thereby correcting camera shake. Can be provided.
　上記の構成を有する発明[１９]によれば、カメラ付き携帯電話の厚みを薄くすることができる。 According to the invention [19] having the above-described configuration, the thickness of the camera-equipped mobile phone can be reduced.
アクチュエータアレイ基板の模式図である。図１（ａ）は基板上に形成された１個のバイモルフ型のカンチレバー型形状記憶合金薄膜アクチュエータの断面図である。図１（ｂ）は図１（ａ）の形状記憶合金薄膜アクチュエータの平面図である。図１（ｃ）はカンチレバー型形状記憶合金薄膜アクチュエータを基板上に並列配置させたアクチュエータアレイ基板を示している。図１（ｄ）はカンチレバー型形状記憶合金薄膜アクチュエータを基板上に環状配置させたアクチュエータアレイ基板を示している。It is a schematic diagram of an actuator array substrate. FIG. 1A is a sectional view of one bimorph type cantilever type shape memory alloy thin film actuator formed on a substrate. FIG. 1B is a plan view of the shape memory alloy thin film actuator of FIG. FIG. 1C shows an actuator array substrate in which cantilever type shape memory alloy thin film actuators are arranged in parallel on the substrate. FIG. 1 (d) shows an actuator array substrate in which cantilever-type shape memory alloy thin film actuators are annularly arranged on the substrate. オートフォーカス駆動機構の組み立て図である。図２（ａ）はアクチュエータアレイ基板、レンズあるいは撮像素子の支持プレート及びバイアスばね（ばね板）をアライメント用の支柱に通して積み上げた図である。図２（ｂ）はばね板の例を示している。図２（ｃ）はばね板の可動部とレンズあるいは撮像素子のプレートを接合してアライメント用の支柱をなくした構造を示している。図２（ｄ）は支持プレートの上面に突設したスペーサーを設けることによって、フラットな形状のばね板を使用した例を示している。It is an assembly drawing of an autofocus drive mechanism. FIG. 2A is a diagram in which an actuator array substrate, a lens or a support plate for an image sensor and a bias spring (spring plate) are passed through alignment columns. FIG. 2B shows an example of a spring plate. FIG. 2C shows a structure in which the movable portion of the spring plate and the lens or the plate of the image sensor are joined to eliminate the alignment support. FIG. 2D shows an example in which a flat spring plate is used by providing a protruding spacer on the upper surface of the support plate. アクチュエータアレイ基板の様々な利用形態を示す図である。図３（ａ）は図２（ａ）のアクチュエータアレイ基板を裏返して用いた形態、図３（ｂ）は基板の両面にアクチュエータアレイを有する形態、図３（ｃ）は複数のアクチュエータアレイ基板を積み重ねた形態、図３（ｄ）は第２のアクチュエータアレイ基板をバイアスばねとして用いた形態を示している。It is a figure which shows the various usage forms of an actuator array board | substrate. 3 (a) shows a form in which the actuator array substrate of FIG. 2 (a) is turned upside down, FIG. 3 (b) shows a form having actuator arrays on both sides of the substrate, and FIG. 3 (c) shows a plurality of actuator array substrates. FIG. 3 (d) shows a form in which the second actuator array substrate is used as a bias spring. バイモルフ型アクチュエータの作製例を示す図である。図４（ａ）は熱酸化によりＳｉＯ２膜を形成させたＳｉウエハ基板上に形状記憶合金薄膜を成膜して結晶化熱処理する工程、図４（ｂ）はフォトエッチングによるパターニングを使って形状記憶合金薄膜をエッチングする工程、図４（ｃ）はＳｉＯ２膜をエッチングする工程、図４（ｄ）はＳｉウエハ基板を等方性エッチングする工程を示している。It is a figure which shows the example of preparation of a bimorph type actuator. FIG. 4A shows a process of forming a shape memory alloy thin film on a Si wafer substrate on which a SiO 2 film is formed by thermal oxidation, and a crystallization heat treatment. FIG. 4B shows a shape using patterning by photoetching. 4C shows a step of etching the memory alloy thin film, FIG. 4C shows a step of etching the SiO 2 film, and FIG. 4D shows a step of isotropic etching of the Si wafer substrate. オートフォーカス駆動機構の駆動原理とシミュレーションモデルを示す図である。図５（ａ）は無負荷の状態のバイモルフ型形状記憶合金薄膜アクチュエータアレイ基板と、移動対象物を支持するプレート及びばね板を積み上げた状態（加熱時）、図５（ｂ）はばね板によってχＢＥＢの初期荷重ＦＢを負荷した状態（加熱時）、図５（ｃ）はレンズの重さなどの一定荷重Ｆが負荷された状態（加熱時）、図５（ｄ）はバイモルフ型形状記憶合金薄膜アクチュエータがＳｉウエハ基板上に押さえつけられた状態（室温）を示している。It is a figure which shows the drive principle and simulation model of an auto-focus drive mechanism. FIG. 5A shows a state in which a bimorph shape memory alloy thin film actuator array substrate in an unloaded state, a plate supporting a moving object, and a spring plate are stacked (when heated), and FIG. an initial load state of F B of chi B E B (when heated), FIG. 5 (c) (during heating) steady state in which the load F is load such as the weight of the lens, FIG. 5 (d) is a bimorph The state (room temperature) in which the mold shape memory alloy thin film actuator is pressed onto the Si wafer substrate is shown. バイモルフ型形状記憶合金薄膜アクチュエータの形状（アクチュエータの長さと、形状記憶合金薄膜及びＳｉＯ２膜の厚さ）を変えたオートフォーカス駆動機構のストロークと許容荷重のシミュレーション結果を示している。The simulation result of the stroke and allowable load of the autofocus driving mechanism in which the shape of the bimorph shape memory alloy thin film actuator (the length of the actuator and the thickness of the shape memory alloy thin film and the SiO 2 film) is changed is shown. （ａ）６ｍｍφの穴を有する１２ｍｍ×１２ｍｍのアクチュエータアレイ基板を示している。（ｂ）１マス（１．２ｍｍ×１．２ｍｍ）内に配置された１０個のバイモルフ型形状記憶合金薄膜アクチュエータ（幅１００μｍ×長さ１０００μｍ）を示している。(A) 12 mm × 12 mm actuator array substrate having 6 mmφ holes. (B) Ten bimorph shape memory alloy thin film actuators (width 100 μm × length 1000 μm) arranged in one square (1.2 mm × 1.2 mm) are shown.
　以下に、添付図面の図１～７を参照して本発明の実施の形態を説明する。
　図１（ａ）、（ｂ）には基板１上に形成されたカンチレバー型形状記憶合金薄膜アクチュエータ２（ここでは形状記憶合金薄膜３とそれよりも熱膨張係数の小さい薄膜４の２層で構成されている）の側面の断面図と平面図を示す。形状記憶合金薄膜アクチュエータ２の形状は通電加熱を行うために図１（ｂ）に示すように概ねＵ字型をしている。ただし、ヒーターなどによる外部加熱を行う場合はこの形状に拘る必要はない。なお、以下では、形状記憶合金薄膜アクチュエータ２を構成する薄膜のうち、基板１に近い側にある薄膜４を便宜的に「下層」とも称する。
　形状記憶合金薄膜アクチュエータ２は、図１（ａ）に示すように、固定端側（図１（ａ）における左側）が基板１に固定され、先端側（図１（ａ）における右側）が基板１から解放されている。また、図１（ａ）では、形状記憶合金薄膜アクチュエータ２が基板１のなす平面（図１（ａ）の紙面左右方向の面）に対して反り上がった形状である状態を示している。 Embodiments of the present invention will be described below with reference to FIGS. 1 to 7 of the accompanying drawings.
1A and 1B show a cantilever-type shape memory alloy thin film actuator 2 (here, a shape memory alloy thin film 3 and a thin film 4 having a smaller thermal expansion coefficient than that) formed on a substrate 1. The cross-sectional view and plan view of the side surface of FIG. The shape of the shape memory alloy thin film actuator 2 is generally U-shaped as shown in FIG. However, it is not necessary to adhere to this shape when performing external heating with a heater or the like. Hereinafter, the thin film 4 on the side close to the substrate 1 among the thin films constituting the shape memory alloy thin film actuator 2 is also referred to as a “lower layer” for convenience.
As shown in FIG. 1A, the shape memory alloy thin film actuator 2 has a fixed end side (left side in FIG. 1A) fixed to the substrate 1 and a tip end side (right side in FIG. 1A) on the substrate. It is released from 1. Further, FIG. 1A shows a state in which the shape memory alloy thin film actuator 2 is warped with respect to the plane formed by the substrate 1 (the surface in the left-right direction in FIG. 1A).
　なお、図１（ａ)のように形状記憶合金薄膜アクチュエータ２を基板１から反り上がった形状にする方法としては、例えば、作製時に施される熱処理によって残留する熱ひずみを利用する方法が挙げられる。また、熱処理後の熱ひずみ以外にも形状記憶処理や成膜時の残留応力を利用する方法なども考えられ、この場合は下層の薄膜４を選択する際に熱膨張係数に拘る必要はなくポリイミドなどの樹脂も下層として使え、また、下層を用いないで形状記憶合金薄膜単体としてもよい。すなわち、本発明において、２層膜であることによって得られる熱ひずみは、形状記憶合金薄膜アクチュエータ２に基板１から反り上がった形状を与えるためだけに使用されるのであって、特許文献３と４及び非特許文献２に見られるようなアクチュエータを駆動するためのバイアス力としての利用は想定していない。そのため、バイモルフ（２層）は必須のものではなく、形状記憶合金薄膜３が基板１から反り上がった形状を持っていれば、ユニモルフ（１層）であってもよい。 As a method for making the shape memory alloy thin film actuator 2 warped from the substrate 1 as shown in FIG. 1 (a), for example, there is a method of utilizing thermal strain remaining by heat treatment performed during fabrication. . In addition to thermal strain after heat treatment, a method using shape memory treatment or residual stress at the time of film formation is also conceivable. In this case, it is not necessary to be concerned with the thermal expansion coefficient when selecting the lower layer thin film 4, and polyimide A resin such as can be used as the lower layer, and the shape memory alloy thin film alone may be used without using the lower layer. That is, in the present invention, the thermal strain obtained by being a two-layer film is used only to give the shape memory alloy thin film actuator 2 a shape warped from the substrate 1. And it is not assumed to be used as a bias force for driving an actuator as seen in Non-Patent Document 2. Therefore, the bimorph (two layers) is not essential, and may be a unimorph (one layer) as long as the shape memory alloy thin film 3 has a shape warped from the substrate 1.
　図１（ｃ）、（ｄ）は、図１（ａ）、（ｂ）に示したような小型のカンチレバー型形状記憶合金薄膜アクチュエータ２（以下、「カンチレバー型アクチュエータ２」とも称する。）を基板１上に多数配置したアクチュエータアレイ基板（図１（ｃ）は並列配置、図１（ｄ）は環状配置）を示す。図１（ｃ）及び（ｄ）では、同じ大きさで向きの異なるカンチレバー型アクチュエータ２が対をなして形成されているが、必ずしも必須条件ではない。ただし、このような形態は水平方向の移動をお互いに打ち消すことから好ましい。本発明では、図１（ｃ）、（ｄ）のように多数のカンチレバー型アクチュエータ２を基板１の一面に配置することによって、後述するように組み立てを簡単にすることができ、動作の信頼性を向上させることができる。また、個々のカンチレバー型アクチュエータ２を独立して制御することにより、基板１に垂直な方向の動き（オートフォーカス機構）だけでなく垂直方向から傾いた動き（手振れ補正機構）も可能になる。 1C and 1D, a small cantilever type shape memory alloy thin film actuator 2 (hereinafter also referred to as “cantilever type actuator 2”) as shown in FIGS. 1A and 1B is a substrate. 1 shows a plurality of actuator array substrates (FIG. 1C is a parallel arrangement, and FIG. 1D is an annular arrangement). In FIGS. 1C and 1D, cantilever actuators 2 having the same size and different orientations are formed in pairs, but this is not necessarily a necessary condition. However, such a form is preferable because the movements in the horizontal direction cancel each other. In the present invention, by arranging a large number of cantilever actuators 2 on one surface of the substrate 1 as shown in FIGS. 1C and 1D, the assembly can be simplified as will be described later, and the operation reliability is improved. Can be improved. In addition, by independently controlling each cantilever actuator 2, not only a movement in a direction perpendicular to the substrate 1 (autofocus mechanism) but also a movement tilted from the vertical direction (camera shake correction mechanism) is possible.
　図２（ａ）は図１のアクチュエータアレイ基板を使ってオートフォーカス駆動機構を組み立てた図である。図２（ａ）に示すように基本的にはアクチュエータアレイ基板７、移動対象物（レンズ８または撮像素子など）を支持するプレート９（以下、「プレート９」とも称する。）、ばね板（バイアスばね）１０を積み重ねた構造であり、ケース（筐体）１２によって当該構造を保持している。アクチュエータ部は基板１の厚さとカンチレバー型アクチュエータ２の変位量の厚さしかなく、厚さ１ｍｍ以下の駆動機構を実現できる。アクチュエータアレイ基板７、プレート９、ばね板１０のいずれのプレートにもアライメント用の穴（例えば、図１（ｃ）、（ｄ）の符号６で示すような支柱穴）を開けておけば、各プレートを支柱１１ａ、１１ｂに通していくだけで簡単に組み立てることができる。このような組み立ての簡便さは、多数のカンチレバー型アクチュエータ２を使ってプレート９とカンチレバー型アクチュエータ２の接触点を複数設けることによって、プレート９を面状に支えている、すなわち、面接触と同等の効果を得ていることによる。カンチレバーの自由端が可動部品に点で接する特許文献３や４に比べて接点の位置を正確に合わせる必要がない。 FIG. 2A is a diagram in which an autofocus drive mechanism is assembled using the actuator array substrate of FIG. As shown in FIG. 2A, basically, an actuator array substrate 7, a plate 9 (hereinafter also referred to as “plate 9”) that supports a moving object (such as a lens 8 or an image sensor), a spring plate (bias). Spring) 10 is stacked, and the case (housing) 12 holds the structure. The actuator portion has only the thickness of the substrate 1 and the displacement amount of the cantilever actuator 2, and a drive mechanism having a thickness of 1 mm or less can be realized. If any of the actuator array substrate 7, plate 9, and spring plate 10 is provided with an alignment hole (for example, a support hole as indicated by reference numeral 6 in FIGS. 1C and 1D), The plate can be easily assembled by simply passing the plate through the columns 11a and 11b. Such assembling is easy because the plate 9 is supported in a plane by providing a plurality of contact points between the plate 9 and the cantilever actuator 2 using a large number of cantilever actuators 2, that is, equivalent to surface contact. By getting the effect of. Compared to Patent Documents 3 and 4 in which the free end of the cantilever is in contact with the movable part at a point, it is not necessary to accurately align the position of the contact.
　このようなアクチュエータアレイ基板の利点を使えば、図２（ｂ）のようなばね板１０の内部の可動部１４が図２（ｃ）のプレート９と接合されていて、さらにばね板1０の固定枠１３がケース１２に固定されていればレンズ８の移動は垂直方向に限定されるので、図２（ｃ）に示すようにアライメント用の支柱さえも省くことができる。図２の例では、バイアス力を与えるバイアスばねとしてばね板を用いているが、スプリング状のばねを用いてもよい。また、ばね板は図２（ａ）に示すような下向きに曲がった形状に限定される必要はなく、フラットな形状であってもよい。その場合は、ばね板１０をプレート９に対して斜めに取り付けるか、図２（ｄ）に示すようにプレート９とばね板１０の間にスペーサー２１を設け、プレート９の上面から突設したスペーサー２１の上端部がばね板１０の下面に接するようにすることによってプレート９を押さえつける力を得ることができる。あるいは、後述するように、バイアスばねとして第２のアクチュエータアレイ基板を用いることもできる。 If the advantage of the actuator array substrate is used, the movable portion 14 inside the spring plate 10 as shown in FIG. 2B is joined to the plate 9 shown in FIG. 2C, and the spring plate 10 is fixed. If the frame 13 is fixed to the case 12, the movement of the lens 8 is limited to the vertical direction, so that even the alignment column can be omitted as shown in FIG. In the example of FIG. 2, a spring plate is used as a bias spring for applying a bias force, but a spring-like spring may be used. Further, the spring plate need not be limited to a downwardly bent shape as shown in FIG. 2A, and may be a flat shape. In that case, the spring plate 10 is attached to the plate 9 at an angle, or a spacer 21 is provided between the plate 9 and the spring plate 10 as shown in FIG. By making the upper end portion of 21 come into contact with the lower surface of the spring plate 10, a force for pressing the plate 9 can be obtained. Alternatively, as described later, the second actuator array substrate can be used as the bias spring.
　なお、図２（ａ）の組み立て図は、本発明のオートフォーカス駆動機構を実現するために最低限必要な構成要素を示したものであり、実際の装置においては、付加的な手振れ補正機構や撮像素子、Ｃｕなどでできた放熱プレート、配線などの要素をケース１２、アクチュエータアレイ基板７、プレート９、ばね板１０などの間に追加挿入してもよい。基板１の裏側に放熱プレートを挿入することにより、形状記憶合金薄膜アクチュエータ２の冷却速度を早くして、応答速度を上げることができる。また、プレート９の形状記憶合金薄膜（カンチレバー型アクチュエータ２を構成する形状記憶合金薄膜３）と接する面に、摩擦係数を下げるようなコーティングを行ってもよく、また、プレート９が導電体の場合は絶縁膜をコーティングする必要がある。 The assembly diagram of FIG. 2A shows the minimum components necessary to realize the autofocus drive mechanism of the present invention. In an actual apparatus, an additional camera shake correction mechanism or Elements such as an image sensor, a heat dissipation plate made of Cu, wiring, and the like may be additionally inserted between the case 12, the actuator array substrate 7, the plate 9, the spring plate 10, and the like. By inserting a heat dissipation plate on the back side of the substrate 1, the cooling speed of the shape memory alloy thin film actuator 2 can be increased and the response speed can be increased. Further, the surface of the plate 9 that contacts the shape memory alloy thin film (the shape memory alloy thin film 3 constituting the cantilever actuator 2) may be coated so as to reduce the friction coefficient. Needs to be coated with an insulating film.
　図３はアクチュエータアレイ基板の様々な応用形態を示したものである。図３（ａ）は図２（ａ）のアクチュエータアレイ基板７を裏返して使用した例であり、この場合は、アクチュエータアレイ基板７にレンズ８を固定することも可能である。図３（ｂ）は基板１の両面にカンチレバー型アクチュエータ２ａ、２ｂのアレイを作製した例であり、これによってレンズ８あるいは撮像素子の変位量を２倍にすることができる。図３（ｃ）は複数のアクチュエータアレイ基板７ａ、７ｂ、７ｃを重ねて、変位量を増やした例である。図３（ｄ）は図２（ａ）のばね板（バイアスばね）１０の代わりに、第２のアクチュエータアレイ基板７ｂをバイアスばねとして用いた例である。この場合、アクチュエータアレイ基板７ｂを構成するカンチレバー型形状記憶合金薄膜アクチュエータ２ｂに通電する電流を制御してバイアスばね７ｂのばね定数を室温で低ヤング率、高温で高ヤング率に設定することにより、ばね定数一定のバイアスばねを使った場合に比べてオートフォーカス駆動機構のストロークを増加させることができる。 FIG. 3 shows various application forms of the actuator array substrate. FIG. 3A is an example in which the actuator array substrate 7 of FIG. 2A is turned upside down. In this case, the lens 8 can be fixed to the actuator array substrate 7. FIG. 3B shows an example in which an array of cantilever actuators 2a and 2b is formed on both surfaces of the substrate 1, whereby the amount of displacement of the lens 8 or the image sensor can be doubled. FIG. 3C shows an example in which a plurality of actuator array substrates 7a, 7b, and 7c are stacked to increase the amount of displacement. FIG. 3D shows an example in which the second actuator array substrate 7b is used as a bias spring instead of the spring plate (bias spring) 10 shown in FIG. In this case, by controlling the current applied to the cantilever shape memory alloy thin film actuator 2b constituting the actuator array substrate 7b and setting the spring constant of the bias spring 7b to a low Young's modulus at room temperature and a high Young's modulus at high temperature, The stroke of the autofocus drive mechanism can be increased compared to the case where a bias spring having a constant spring constant is used.
　図４に示すように、図１に示したような形状記憶合金薄膜アクチュエータ２のアレイは、例えば、半導体プロセスで作製可能である。図４では、バイモルフ型アクチュエータの下層膜としてＳｉＯ２膜１５ａを使用しているが、同様なプロセスによってＳｉＮ膜などを作製して下層膜に用いることもできる。図４（ａ）ではＳｉウエハ基板１６上に熱酸化によってＳｉＯ２膜１５ａ及び１５ｂを形成させる。ＳｉＯ２膜１５ａの厚さは酸化時間等の酸化条件を選ぶことで変えることができる。なお、ＳｉＯ２膜はＣＶＤ法などの他の方法によって作られてもよい。熱酸化によりＳｉＯ２膜を形成させたＳｉウエハ基板１６上にスパッタリング法によって形状記憶合金薄膜３を成膜する。形状記憶合金薄膜３の厚さは成膜時間などのスパッタ条件によって変えることができる。成膜後の薄膜はアモルファスなので、例えば５００℃以上で熱処理を行うことによって薄膜を結晶化させる。熱処理後に残る熱ひずみは、形状記憶合金薄膜アクチュエータ２（形状記憶合金薄膜３とＳｉＯ２膜１５ａ）をＳｉウエハ基板１６から反り上がった形状に変える重要な役割を果たす（図４（ｄ））を参照）。 As shown in FIG. 4, the array of shape memory alloy thin film actuators 2 as shown in FIG. 1 can be manufactured by, for example, a semiconductor process. In FIG. 4, the SiO 2 film 15 a is used as the lower layer film of the bimorph actuator, but an SiN film or the like can be produced by the same process and used as the lower layer film. In FIG. 4A, SiO 2 films 15a and 15b are formed on the Si wafer substrate 16 by thermal oxidation. The thickness of the SiO 2 film 15a can be changed by selecting an oxidation condition such as an oxidation time. Note that the SiO 2 film may be formed by other methods such as a CVD method. The shape memory alloy thin film 3 is formed by sputtering on the Si wafer substrate 16 on which the SiO 2 film is formed by thermal oxidation. The thickness of the shape memory alloy thin film 3 can be changed according to sputtering conditions such as film formation time. Since the thin film after film formation is amorphous, the thin film is crystallized by performing heat treatment at, for example, 500 ° C. or higher. The thermal strain remaining after the heat treatment plays an important role in changing the shape memory alloy thin film actuator 2 (the shape memory alloy thin film 3 and the SiO 2 film 15a) to a shape warped from the Si wafer substrate 16 (FIG. 4D). reference).
　形状記憶合金薄膜としては、Ｔｉ－Ｎｉ、Ｔｉ－Ｎｉ－Ｃｕ、Ｔｉ－Ｎｉ－Ｐｄ、Ｔｉ－Ｎｉ－Ｈｆ、Ｔｉ－Ｎｉ－Ｚｒ、Ｃｕ－Ａｌ－Ｎｉ合金などの形状記憶効果を示す合金の薄膜ならなんでもよいが、５０原子％以上で５５原子％以下のＴｉと５原子％以上で１０原子％以下のＣｕを含むＴｉ－Ｎｉ－Ｃｕ合金薄膜、５０原子％以上で５５原子％以下のＴｉと１０原子％を超えて２０原子％以下のＣｕを含むＴｉ－Ｎｉ－Ｃｕ合金薄膜、あるいは４５原子％以上で５０原子％未満のＴｉと原子％で１０＋１．６×（５０－Ｔｉの原子％）を超えて２０＋１．６×（５０－Ｔｉの原子％）以下のＣｕを含むＴｉ－Ｎｉ－Ｃｕ合金薄膜を用いるのがよい。
　このような組成の合金薄膜によれば、Ｔｉ－Ｎｉ合金よりも変態温度が高くて温度ヒステリシスが小さく、発生力が大きくて応答性に優れた形状記憶合金薄膜を使ったアクチュエータアレイを作製することができる。 Shape memory alloy thin films include alloys showing shape memory effects such as Ti—Ni, Ti—Ni—Cu, Ti—Ni—Pd, Ti—Ni—Hf, Ti—Ni—Zr, Cu—Al—Ni alloys. Any thin film may be used, but a Ti—Ni—Cu alloy thin film containing 50 atomic% to 55 atomic% Ti and 5 atomic% to 10 atomic% Cu, 50 atomic% to 55 atomic% Ti Ti-Ni-Cu alloy thin film containing more than 10 atomic% and 20 atomic% or less of Cu, or 45 atomic% or more and less than 50 atomic% of Ti and atomic% of 10 + 1.6 × (50-Ti atomic% It is preferable to use a Ti—Ni—Cu alloy thin film containing Cu exceeding 20 + 1.6 × (50-Ti atomic%) and less.
According to the alloy thin film having such a composition, an actuator array using a shape memory alloy thin film having a transformation temperature higher than that of a Ti—Ni alloy, a small temperature hysteresis, a large generated force, and excellent responsiveness can be manufactured. Can do.
　好ましくは、５０原子％以上で５５原子％以下のＴｉと１０原子％を超えて２０原子％以下のＣｕを含むＴｉ－Ｎｉ－Ｃｕ合金薄膜あるいは４５原子％以上で５０原子％未満のＴｉと原子％で１０＋１．６×（５０－Ｔｉの原子％）を超えて２０＋１．６×（５０－Ｔｉの原子％）以下のＣｕを含むＴｉ－Ｎｉ－Ｃｕ合金薄膜を用いるのがよい。
　このような組成の合金薄膜によれば、Ｔｉ－Ｎｉ－Ｃｕ合金ワイヤよりも格段に発生力が大きく、特性の組成依存性が小さくて組成制御が難しいスパッタリングにおいても安定した特性（大きい力、高い応答性、高い変態温度）を示す形状記憶合金薄膜を使ったアクチュエータアレイを安価で大量に製造することができる。 Preferably, a Ti—Ni—Cu alloy thin film containing 50 atomic% or more and 55 atomic% or less of Ti and more than 10 atomic% and 20 atomic% or less of Cu or 45 atomic% or more and less than 50 atomic% of Ti and atoms It is preferable to use a Ti—Ni—Cu alloy thin film containing 10 + 1.6 × (50-Ti atomic%) and 20 + 1.6 × (50-Ti atomic%) or less of Cu.
According to the alloy thin film having such a composition, the generated force is remarkably larger than that of the Ti—Ni—Cu alloy wire, and stable characteristics (high force, high) are obtained even in sputtering in which composition control of properties is small and composition control is difficult. An actuator array using a shape memory alloy thin film exhibiting responsiveness and high transformation temperature can be manufactured in large quantities at low cost.
　より好ましくは、５０原子％以上で５５原子％以下のＴｉと１０原子％を超えて２０原子％以下のＣｕを含むＴｉ－Ｎｉ－Ｃｕ形状記憶合金薄膜を用いることによって、変態温度がより高くて信頼性に優れた形状記憶合金薄膜を使ったアクチュエータアレイ（非特許文献３）を作製することができる。 More preferably, by using a Ti—Ni—Cu shape memory alloy thin film containing 50 atomic% or more and 55 atomic% or less of Ti and 10 atomic% or more and 20 atomic% or less of Cu, the transformation temperature is higher. An actuator array (non-patent document 3) using a shape memory alloy thin film having excellent reliability can be manufactured.
　図４（ｂ）では形状記憶合金薄膜３の上にネガレジストをスピンコートしてフォトエッチングによるパターニングを行う。レジストをマスクにして、形状記憶合金薄膜３の必要としない部分を、希釈したＨＦ／ＨＮＯ３でエッチング除去するか、硫酸／メタノール混合液などによって電解エッチングする。
　次に、図４（ｃ）で、下地のＳｉＯ２膜１５ａをバッファードフッ酸によってエッチングする。 In FIG. 4B, a negative resist is spin-coated on the shape memory alloy thin film 3 and patterning is performed by photoetching. Using the resist as a mask, unnecessary portions of the shape memory alloy thin film 3 are removed by etching with diluted HF / HNO 3 , or electrolytically etched with a sulfuric acid / methanol mixed solution or the like.
Next, in FIG. 4C, the underlying SiO 2 film 15a is etched with buffered hydrofluoric acid.
　図４（ｄ）で、さらに、ＳｉＯ２膜１５ａの下のＳｉウエハ基板１６を、ＸｅＦ２ガスを使って等方性エッチングすることにより、形状記憶合金薄膜３とＳｉＯ２膜１５ａからなる２層膜（形状記憶合金薄膜アクチュエータ２）をＳｉウエハ基板１６から解放する。この際に２層膜がＳｉウエハ基板１６から反り上がった形状を得るためには、形状記憶合金薄膜の下層に形状記憶合金薄膜より熱膨張係数の小さい材料、例えばＳｉＯ２を用いることが必須である。熱膨張係数が大きい材料を用いた場合は、２層膜が基板側に湾曲してしまうためにアクチュエータとして使えない。
　なお、図４に示す半導体プロセスは形状記憶合金薄膜アクチュエータ２のアレイの作製法の一例であり、図１（ａ）、（ｂ）に示すような形状記憶合金薄膜アクチュエータの構成や、図１（ｃ）、（ｄ）に示すようなアクチュエータアレイ基板の構造を実現できれば、図４の工程に沿う必要はなく、Ｓｉを使った半導体プロセスに拘る必要もない。例えば、アクチュエータアレイ基板の基板として金属や樹脂あるいはガラスの基板を用いることによって、オートフォーカス駆動機構の製造コストを低減することができる。 In FIG. 4D, the Si wafer substrate 16 under the SiO 2 film 15a is further isotropically etched using XeF 2 gas to thereby form two layers of the shape memory alloy thin film 3 and the SiO 2 film 15a. The film (shape memory alloy thin film actuator 2) is released from the Si wafer substrate 16. At this time, in order to obtain a shape in which the two-layer film is warped from the Si wafer substrate 16, it is essential to use a material having a smaller thermal expansion coefficient than the shape memory alloy thin film, for example, SiO 2, as the lower layer of the shape memory alloy thin film. is there. When a material having a large thermal expansion coefficient is used, the two-layer film is curved toward the substrate side and cannot be used as an actuator.
Note that the semiconductor process shown in FIG. 4 is an example of a method for producing an array of shape memory alloy thin film actuators 2, and the configuration of the shape memory alloy thin film actuator as shown in FIGS. If the structure of the actuator array substrate as shown in c) and (d) can be realized, it is not necessary to follow the process of FIG. 4 and it is not necessary to be involved in a semiconductor process using Si. For example, by using a metal, resin, or glass substrate as the actuator array substrate, the manufacturing cost of the autofocus drive mechanism can be reduced.
　図５に本発明によるオートフォーカス駆動機構の駆動原理と設計に用いたシミュレーションモデルを示す。図５（ａ）は、高温加熱時（Ｔｉ－Ｎｉ－Ｃｕ形状記憶合金薄膜１８がオーステナイト相の状態）において、ケース（筐体）底面２０にアクチュエータアレイ基板（基板１と形状記憶合金薄膜アクチュエータ２で構成される）と移動対象物を支持するプレート９（以下、「プレート９」とも称する。）及びばね板１０を積み上げた状態を示す。ＥＡ及びＥＢはばね定数、δＴは形状記憶合金薄膜アクチュエータ２の基板１の面からの高さである。図５（ｂ）は、形状記憶合金薄膜アクチュエータ２にばね板１０からＦＢの力を与えた時の状態を示す。χＢは、ばね板１０の垂直方向の収縮量（ケース上蓋１９の変位量）、δＢは形状記憶合金薄膜アクチュエータ２の垂直方向の収縮量（ケース底面２０の変位量）である。 FIG. 5 shows the driving principle of the autofocus driving mechanism according to the present invention and the simulation model used for the design. FIG. 5A shows an actuator array substrate (substrate 1 and shape memory alloy thin film actuator 2) on the bottom surface 20 of the case (housing) during high temperature heating (when the Ti—Ni—Cu shape memory alloy thin film 18 is in the austenite phase). And a plate 9 (hereinafter also referred to as “plate 9”) and a spring plate 10 supporting the moving object. E A and E B are spring constants, and δ T is the height of the shape memory alloy thin film actuator 2 from the surface of the substrate 1. 5 (b) shows a state in which the spring plate 10 in the shape memory alloy thin film actuator 2 gave a force F B. χ B is the vertical contraction amount of the spring plate 10 (displacement amount of the case upper lid 19), and δ B is the vertical contraction amount of the shape memory alloy thin film actuator 2 (displacement amount of the case bottom surface 20).
　図５（ｃ）は、さらに形状記憶合金薄膜アクチュエータ２に外部から力Ｆ（例えばレンズの重さなど）が負荷された時の状態を示す。δＷは外力Ｆによって形状記憶合金薄膜アクチュエータ２が垂直方向に収縮した量であり、δは形状記憶合金薄膜アクチュエータ２の基板１からの高さ（すなわち、δ＝δＴ－δＢ－δＷ）である。δは高温時（δＨ）と低温時（δＬ）で異なり、この差がプレート９のストロークになる。ばね板１０から働く力ＦＢが小さい場合は、δＬ＞δＨとなり、Ｔｉ－Ｎｉ－Ｃｕ形状記憶合金薄膜１８がプレート９を低温時に支えることになり、加熱時の逆変態による形状回復力をプレート９の移動に使うことができない。しかし、ばね板１０の力ＦＢを大きくすることによってδＬ＜δＨにすることができて加熱時の形状回復力を利用してプレート９を持ち上げることができるようになる。さらに適切なＦＢの値を選ぶことによって、δＬ＜０＜δＨに設定することができる。この場合、図５（ｄ）のように、プレート９の移動は、Ｔｉ－Ｎｉ－Ｃｕ形状記憶合金薄膜１８のマルテンサイト変態の途中で基板１によって止められる。変態終了温度の手前の高い温度でプレート９の移動が停止するために作動温度をＴｉ－Ｎｉ－Ｃｕ形状記憶合金薄膜１８のマルテンサイト変態終了温度（６０℃）よりも高い７０℃以上に設定することができ、駆動機構の信頼性を上げることができる。同時に、基板１は不要な変形を阻止してＴｉ－Ｎｉ－Ｃｕ形状記憶合金薄膜１８への塑性変形の導入を防ぐ効果も有する。すなわち、駆動機構ユニットの中に別途ストッパを作りこまなくても、基板１でその機能を代用できる。 FIG. 5C shows a state when a force F (for example, a lens weight) is further applied to the shape memory alloy thin film actuator 2 from the outside. δ W is an amount of the shape memory alloy thin film actuator 2 contracted in the vertical direction by the external force F, and δ is the height of the shape memory alloy thin film actuator 2 from the substrate 1 (that is, δ = δ T −δ B −δ W ). δ differs between high temperature (δ H ) and low temperature (δ L ), and this difference becomes the stroke of the plate 9. When the force F B acting from the spring plate 10 is small, δ L > δ H , and the Ti—Ni—Cu shape memory alloy thin film 18 supports the plate 9 at a low temperature, and the shape recovery force due to reverse transformation during heating. Cannot be used to move the plate 9. However, it is possible to lift the plate 9 by using the shape recovery force during heating can be [delta] L <[delta] H by increasing the force F B of the spring plate 10. By choosing a more appropriate value for F B, it can be set to δ L <0 <δ H. In this case, as shown in FIG. 5D, the movement of the plate 9 is stopped by the substrate 1 during the martensitic transformation of the Ti—Ni—Cu shape memory alloy thin film 18. In order to stop the movement of the plate 9 at a temperature just before the transformation end temperature, the operating temperature is set to 70 ° C. or higher, which is higher than the martensite transformation end temperature (60 ° C.) of the Ti—Ni—Cu shape memory alloy thin film 18. This can increase the reliability of the drive mechanism. At the same time, the substrate 1 also has an effect of preventing unnecessary deformation and preventing introduction of plastic deformation into the Ti—Ni—Cu shape memory alloy thin film 18. That is, the function can be substituted by the substrate 1 without making a separate stopper in the drive mechanism unit.
　図５のモデルを使ってシミュレーションを行った結果を図６に示す。アレイを構成するカンチレバー型形状記憶合金薄膜アクチュエータの形状（アクチュエータの長さと、形状記憶合金薄膜及びＳｉＯ２膜の厚さ）を変えることで、１００～６００μｍのストロークと１４ｇｆを超える荷重を許容できるオートフォーカス駆動機構が作製できる。また、多くの場合、δＬ＜０＜δＨとなって、形状記憶合金薄膜のマルテンサイト変態の一部を使うことにより、作動温度の上昇を見込むことができる。表中６番と７番の比較ではアクチュエータ形状とレンズによる荷重は同じであるが、バイアスばねをほとんど使わない（ばね板による荷重が０．１２ｇｆである）６番の例では、δＬ＞δＨとなって形状記憶合金薄膜の加熱時に発生する大きい形状回復力を利用できず、ストローク（δＨ－δＬの絶対値）は２１μｍに留まる。一方、バイアスばねによる荷重を増やした（ばね板による荷重が２．０９ｇｆである）７番の例では、δＬ＜δＨと変位が逆転し、３００μｍのストローク（δＬの値が負の値であるため、δＨの値の全量）が得られる。すなわち、形状記憶合金薄膜の形状回復力を利用する（形状記憶合金薄膜アクチュエータが加熱時のオーステナイト相で反り上がった形状となり、冷却時のマルテンサイト相で平坦な形状になる）ためには、できるだけ大きい荷重で使う必要があり、レンズによる荷重が小さい場合には、バイアスばねで荷重を補うことが必要である。８番の例は特許文献３に記載されているように可動部品の対向する２辺に沿って延びるように設置した２本の長いバイモルフ型アクチュエータでレンズを支えた場合であるが、δＬ（－１３５５８２μｍ）とδＨ（３００μｍ）の比較からレンズ（移動対象物）の駆動に使える形状記憶合金薄膜のマルテンサイト変態はごくわずかであり、３００μｍのストロークは得られるものの、利用できる荷重は０．０２ｇｆと非常に小さいことがわかる。 FIG. 6 shows the result of simulation using the model of FIG. By changing the shape of the cantilever-type shape memory alloy thin film actuator (actuator length and shape memory alloy thin film and SiO 2 film thickness) constituting the array, an auto that can tolerate a stroke of 100 to 600 μm and a load exceeding 14 gf A focus drive mechanism can be manufactured. Further, in many cases, δ L <0 <δ H, and by using a part of the martensitic transformation of the shape memory alloy thin film, it is possible to expect an increase in operating temperature. In the comparison between No. 6 and No. 7 in the table, the actuator shape and the load by the lens are the same, but in the example of No. 6 that uses almost no bias spring (the load by the spring plate is 0.12 gf), δ L > δ The large shape recovery force generated when heating the shape memory alloy thin film becomes H cannot be used, and the stroke (absolute value of δ H −δ L ) remains at 21 μm. On the other hand, in the seventh example in which the load by the bias spring is increased (the load by the spring plate is 2.09 gf), the displacement is reversed with δ L <δ H, and the stroke of 300 μm (the value of δ L is a negative value). because it is, the total amount of the value of [delta] H) are obtained. That is, in order to utilize the shape recovery force of the shape memory alloy thin film (the shape memory alloy thin film actuator is warped in the austenite phase during heating and becomes flat in the martensite phase during cooling) as much as possible. It is necessary to use with a large load, and when the load by the lens is small, it is necessary to supplement the load with a bias spring. The example of No. 8 is a case where the lens is supported by two long bimorph actuators installed so as to extend along two opposing sides of the movable part as described in Patent Document 3, but δ L ( -135582 μm) and δ H (300 μm), the shape memory alloy thin film that can be used for driving the lens (moving object) has very little martensitic transformation, and although a stroke of 300 μm can be obtained, the usable load is 0. It can be seen that it is very small as 02 gf.
　図７は図６のシミュレーションを行う際に使用した、アクチュエータアレイ基板７の構成図である。図７（ａ）に示すように１２ｍｍ×１２ｍｍの基板に６ｍｍφのレンズのための開口窓５を開けると想定すると、１マスを１．２ｍｍ×１．２ｍｍとして合計６４マスに、アクチュエータのアレイを配置することができる。つまり、図５に示すバイモルフ型形状記憶合金薄膜アクチュエータ２が幅１００μｍ、長さ１０００μｍの場合、図７（ｂ）に示すように１マス（１．２ｍｍ×１．２ｍｍ）あたり１０本配置できるので、６４マスの合計で１０×６４＝６４０本、作製できる。なお、移動対象物が撮像素子の場合は、中央に穴をあける必要がないので、その場合はアクチュエータを１０００本搭載することができ、図６に示した許容できる荷重はそれぞれ約１．５６倍になる。 FIG. 7 is a configuration diagram of the actuator array substrate 7 used when the simulation of FIG. 6 is performed. Assuming that an opening window 5 for a 6 mmφ lens is opened on a 12 mm × 12 mm substrate as shown in FIG. 7A, one cell is 1.2 mm × 1.2 mm and a total of 64 cells is arranged. Can be arranged. That is, when the bimorph shape memory alloy thin film actuator 2 shown in FIG. 5 has a width of 100 μm and a length of 1000 μm, 10 pieces can be arranged per square (1.2 mm × 1.2 mm) as shown in FIG. , 64 × 640 in total can be produced. When the moving object is an image sensor, there is no need to make a hole in the center. In that case, 1000 actuators can be mounted, and the allowable load shown in FIG. become.
　なお、上記の実施形態においては、オートフォーカス駆動機構として種々の構成例を示したが、本発明はこれに限定されるものではなく、当業者として、適宜の設計変更を行いうることは言うまでもない。 In the above embodiment, various configuration examples are shown as the autofocus drive mechanism. However, the present invention is not limited to this, and it goes without saying that appropriate design changes can be made by those skilled in the art. .
　本発明のオートフォーカス駆動機構によれば、基板に垂直な方向にレンズの位置を変えることができる（オートフォーカス機能）。さらに個々のアクチュエータを独立して動かせば、垂直方向から傾ける（手振れ補正機構）こともできる。 According to the autofocus drive mechanism of the present invention, the lens position can be changed in a direction perpendicular to the substrate (autofocus function). Furthermore, if each actuator is moved independently, it can also be tilted from the vertical direction (camera shake correction mechanism).
１、１ａ、１ｂ、１ｃ　基板
２、２ａ、２ｂ、２ｃ　カンチレバー型形状記憶合金薄膜アクチュエータ
３　形状記憶合金薄膜（上層）
４　薄膜（下層）
５　レンズ用開口窓
６　アライメント用の支柱穴
７、７ａ、７ｂ、７ｃ　アクチュエータアレイ基板
８　レンズ（移動対象物）
９　移動対象物を支持するプレート
１０　ばね板
１１ａ、１１ｂ　アライメント用の支柱
１２　ケース（筐体）
１３　ばね板固定枠
１４　ばね板可動部
１５ａ、１５ｂ　ＳｉＯ２膜
１６　Ｓｉウエハ基板
１７　ＳｉＯ２膜
１８　Ｔｉ－Ｎｉ－Ｃｕ形状記憶合金薄膜
１９　ケース（筐体）上蓋
２０　ケース（筐体）底面
２１　スペーサー 1, 1a, 1b, 1c Substrate 2, 2a, 2b, 2c Cantilever type shape memory alloy thin film actuator 3 Shape memory alloy thin film (upper layer)
4 Thin film (lower layer)
5 Lens opening window 6 Alignment column holes 7, 7a, 7b, 7c Actuator array substrate 8 Lens (moving object)
9 Plate 10 for supporting moving object Spring plate 11a, 11b Column 12 for alignment Case (housing)
13 Spring plate fixing frame 14 Spring plate movable portion 15a, 15b SiO 2 film 16 Si wafer substrate 17 SiO 2 film 18 Ti—Ni—Cu shape memory alloy thin film 19 Case (housing) upper lid 20 Case (housing) bottom surface 21 Spacer

Claims (19)

  1. 　固定端側が基板に固定され、先端側が基板から解放されて反り上がった複数の形状記憶合金薄膜が前記基板上で面状に並べられてアクチュエータアレイを構成しているアクチュエータアレイ基板と、
    　移動対象物を支持するプレートと、
    　前記複数の形状記憶合金薄膜が、オーステナイト相で前記基板のなす平面に対して反り上がった形状となり、マルテンサイト相で前記基板のなす平面に対して大略平坦となるようなバイアス力を与えるバイアスばねを備え、
    　前記アクチュエータアレイ基板、前記プレート、および前記バイアスばねが積層された構造を保持する筐体を備えることを特徴とするオートフォーカス駆動機構。     An actuator array substrate in which a fixed end side is fixed to the substrate, and a plurality of shape memory alloy thin films that are warped up and released from the substrate are arranged in a plane on the substrate to form an actuator array;
    A plate that supports the moving object;
    A bias spring that applies a biasing force so that the plurality of shape memory alloy thin films are warped with respect to the plane formed by the substrate in the austenite phase and are substantially flat with respect to the plane formed by the substrate in the martensite phase. With
    An autofocus drive mechanism comprising a housing that holds a structure in which the actuator array substrate, the plate, and the bias spring are stacked.
  2. 　室温時に前記対象物を支持するプレートの移動が前記アクチュエータアレイ基板の基板によって停止することによって、形状記憶合金薄膜の変態ひずみを越えた余分な塑性変形を防ぐことを特徴とする請求項１に記載のオートフォーカス駆動機構。 The excessive plastic deformation beyond the transformation strain of the shape memory alloy thin film is prevented by stopping movement of the plate supporting the object at room temperature by the substrate of the actuator array substrate. Autofocus drive mechanism.
  3. 　前記対象物を支持するプレートの移動が前記形状記憶合金薄膜のマルテンサイト変態終了温度よりも高い温度で前記アクチュエータアレイ基板の基板によって停止することを特徴とする請求項２に記載のオートフォーカス駆動機構。 3. The autofocus drive mechanism according to claim 2, wherein the movement of the plate supporting the object is stopped by the substrate of the actuator array substrate at a temperature higher than a martensitic transformation end temperature of the shape memory alloy thin film. .
  4. 　前記形状記憶合金薄膜が当該形状記憶合金薄膜の熱膨張係数よりも小さな熱膨張係数を有する下層の薄膜と積層され、熱処理後の熱ひずみによって、当該形状記憶合金薄膜がオーステナイト相で前記基板に対して反り上がった形状とされたことを特徴とする請求項１～３のいずれか一項に記載のオートフォーカス駆動機構。 The shape memory alloy thin film is laminated with a lower layer thin film having a thermal expansion coefficient smaller than the thermal expansion coefficient of the shape memory alloy thin film, and the shape memory alloy thin film is austenitic with respect to the substrate by thermal strain after heat treatment. The autofocus drive mechanism according to any one of claims 1 to 3, wherein the autofocus drive mechanism has a warped shape.
  5. 　前記形状記憶合金薄膜の熱膨張係数よりも小さな熱膨張係数を有する下層の薄膜は、ＳｉＯ２薄膜であることを特徴とする請求項４に記載のオートフォーカス駆動機構。 The shape lower film having a smaller thermal expansion coefficient than the thermal expansion coefficient of the storage alloy thin film, auto-focus drive mechanism according to claim 4, characterized in that the SiO 2 thin film.
  6. 　前記移動対象物を支持するプレートの上面にスペーサーが突設されており、当該スペーサーの上端部が前記バイアスばねの下面に接するように構成されたことを特徴とする請求項１～５のいずれか一項に記載のオートフォーカス駆動機構。 6. The spacer according to claim 1, further comprising a spacer projecting from an upper surface of the plate that supports the moving object, wherein an upper end portion of the spacer is in contact with a lower surface of the bias spring. The autofocus drive mechanism according to one item.
  7. 　前記バイアスばねが、前記アクチュエータアレイ基板と同様の構成を有する第２のアクチュエータアレイ基板であることを特徴とする請求項１～５のいずれか一項に記載のオートフォーカス駆動機構。 6. The autofocus drive mechanism according to claim 1, wherein the bias spring is a second actuator array substrate having a configuration similar to that of the actuator array substrate.
  8. 　前記基板は、Ｓｉウエハ基板であることを特徴とする請求項１～７のいずれか一項に記載のオートフォーカス駆動機構。 The autofocus drive mechanism according to any one of claims 1 to 7, wherein the substrate is a Si wafer substrate.
  9. 　前記形状記憶合金薄膜は、組成元素を、
    　５０原子％以上で５５原子％以下のＴｉ、
    　１０原子％を超えて２０原子％以下のＣｕ、
    　残部をＮｉおよび不可避的不純物とする、
    　Ｔｉ－Ｎｉ－Ｃｕ合金薄膜であることを特徴とする請求項１～８のいずれか一項に記載のオートフォーカス駆動機構。     The shape memory alloy thin film contains a composition element,
    50 atomic% or more and 55 atomic% or less of Ti,
    Cu exceeding 10 atomic% and not exceeding 20 atomic%,
    The balance is Ni and inevitable impurities,
    9. The autofocus drive mechanism according to claim 1, wherein the autofocus drive mechanism is a Ti—Ni—Cu alloy thin film.
  10. 　前記形状記憶合金薄膜は、組成元素を、
    　４５原子％以上で５０原子％未満のＴｉ、
    　原子％で１０＋１．６×（５０－Ｔｉの原子％）を超えて２０＋１．６×（５０－Ｔｉの原子％）以下のＣｕ、
    　残部をＮｉおよび不可避的不純物とする、
    　Ｔｉ－Ｎｉ－Ｃｕ合金薄膜であることを特徴とする請求項１～８のいずれか一項に記載のオートフォーカス駆動機構。     The shape memory alloy thin film contains a composition element,
    Ti of 45 atomic% or more and less than 50 atomic%,
    Cu of not less than 10 + 1.6 × (atomic percent of 50-Ti) and not more than 20 + 1.6 × (atomic percent of 50-Ti) in atomic percent,
    The balance is Ni and inevitable impurities,
    9. The autofocus drive mechanism according to claim 1, wherein the autofocus drive mechanism is a Ti—Ni—Cu alloy thin film.
  11. 　前記形状記憶合金薄膜は、組成元素を、
    　５０原子％以上で５５原子％以下のＴｉ、
    　５原子％以上で１０原子％以下のＣｕ、
    　残部をＮｉおよび不可避的不純物とする、
    　Ｔｉ－Ｎｉ－Ｃｕ合金薄膜であることを特徴とする請求項１～８のいずれか一項に記載のオートフォーカス駆動機構。     The shape memory alloy thin film contains a composition element,
    50 atomic% or more and 55 atomic% or less of Ti,
    Cu of 5 atomic% or more and 10 atomic% or less,
    The balance is Ni and inevitable impurities,
    9. The autofocus drive mechanism according to claim 1, wherein the autofocus drive mechanism is a Ti—Ni—Cu alloy thin film.
  12. 　前記移動対象物は、レンズ又は撮像素子であることを特徴とする請求項１～１１のいずれか一項に記載のオートフォーカス駆動機構。 The autofocus drive mechanism according to any one of claims 1 to 11, wherein the moving object is a lens or an image sensor.
  13. 　前記移動対象物はレンズであり、前記基板は光路確保のための開口窓を有し、
    　前記アクチュエータアレイ基板における複数の形状記憶合金薄膜の配置は、前記開口窓を囲うように、前記基板に大略均一な密度で配置されていることを特徴とする請求項１～１１のいずれか一項に記載のオートフォーカス駆動機構。     The moving object is a lens, and the substrate has an opening window for securing an optical path;
    12. The plurality of shape memory alloy thin films on the actuator array substrate are arranged on the substrate at a substantially uniform density so as to surround the opening window. The autofocus drive mechanism described in 1.
  14. 　請求項１～１３のいずれか一項に記載のオートフォーカス駆動機構を有し、前記形状記憶合金薄膜を加熱する手段によって、当該形状記憶合金薄膜のオーステナイト相とマルテンサイト相の組織割合が調整されてオートフォーカスを行う機能を具備するように構成したことを特徴とするカメラモジュール。 The structure ratio of the austenite phase and the martensite phase of the shape memory alloy thin film is adjusted by the means for heating the shape memory alloy thin film, comprising the autofocus drive mechanism according to any one of claims 1 to 13. The camera module is configured to have a function of performing autofocus.
  15. 　オートフォーカス制御回路からの駆動電流を前記複数の形状記憶合金薄膜に通電することにより、前記複数の形状記憶合金薄膜の電気抵抗を制御して、オートフォーカスを行う機能を具備するように構成したことを特徴とする請求項１４に記載のカメラモジュール。 It is configured to have a function of performing autofocus by controlling the electrical resistance of the plurality of shape memory alloy thin films by passing a driving current from an autofocus control circuit to the plurality of shape memory alloy thin films. The camera module according to claim 14.
  16. 　前記形状記憶合金薄膜は、固定端側の一端から先端側を経由して前記固定端側の他端に通電するように構成されたことを特徴とする請求項１５に記載のカメラモジュール。 The camera module according to claim 15, wherein the shape memory alloy thin film is configured to energize from one end on the fixed end side to the other end on the fixed end side via the tip end side.
  17. 　前記加熱手段は、前記形状記憶合金薄膜の周囲に形成された電熱導体であることを特徴とする請求項１４に記載のカメラモジュール。 15. The camera module according to claim 14, wherein the heating means is an electric heat conductor formed around the shape memory alloy thin film.
  18. 　駆動電流を前記複数の形状記憶合金薄膜の個々の形状記憶合金薄膜に独立して通電することにより、手振れ補正機能を具備するように構成したことを特徴とする請求項１４～１７のいずれか一項に記載のカメラモジュール。 18. A camera shake correction function is provided by energizing a drive current to each of the plurality of shape memory alloy thin films independently of each other to form a camera shake correction function. The camera module according to item.
  19. 　請求項１４～１８のいずれか一項に記載のカメラモジュールを搭載したことを特徴とするカメラ付き携帯電話。 A camera-equipped mobile phone, comprising the camera module according to any one of claims 14 to 18.
PCT/JP2019/008340 2018-04-12 2019-03-04 Autofocus drive mechanism using shape-memory-alloy thin film actuator array WO2019181455A1 (en)

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JPH09127398A (en) * 1995-10-31 1997-05-16 Kyocera Corp Lens driving mechanism
JP2006055991A (en) * 2004-08-20 2006-03-02 Palo Alto Research Center Inc Mems device using stressed material and shape memory material and its manufacturing method
JP2006348319A (en) * 2005-06-13 2006-12-28 National Institute For Materials Science TERNARY Ti-Ni-Cu SHAPE MEMORY ALLOY AND ITS MANUFACTURING METHOD
JP2009089306A (en) * 2007-10-03 2009-04-23 Konica Minolta Holdings Inc Movement mechanism, imaging unit, and imaging apparatus
JP2010169800A (en) * 2009-01-21 2010-08-05 Konica Minolta Holdings Inc Driving device and imaging apparatus
JP2011109853A (en) * 2009-11-19 2011-06-02 Konica Minolta Holdings Inc Actuator manufacturing method, actuator, moving mechanism, and camera module
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* Cited by examiner, † Cited by third party
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JPH06172886A (en) * 1991-06-15 1994-06-21 Takeshi Masumoto Ti-ni-cu shape memory alloy
JPH09127398A (en) * 1995-10-31 1997-05-16 Kyocera Corp Lens driving mechanism
JP2006055991A (en) * 2004-08-20 2006-03-02 Palo Alto Research Center Inc Mems device using stressed material and shape memory material and its manufacturing method
JP2006348319A (en) * 2005-06-13 2006-12-28 National Institute For Materials Science TERNARY Ti-Ni-Cu SHAPE MEMORY ALLOY AND ITS MANUFACTURING METHOD
JP2009089306A (en) * 2007-10-03 2009-04-23 Konica Minolta Holdings Inc Movement mechanism, imaging unit, and imaging apparatus
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WO2017170046A1 (en) * 2016-03-29 2017-10-05 富士フイルム株式会社 Focusing mechanism and imaging module

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