JP2014186213A - MEMS device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a MEMS device in which a natural oxidation film of an electrode on a MEMS chip side is properly removed using ultrasonic waves during a wire bonding process, and which prevents displacement parts from being damaged by the ultrasonic waves propagated through wires.SOLUTION: An optical deflector chip 1 includes displacement parts such as a mirror unit 9 supported by a support frame unit 2 so as to be freely displaced and electrode pads 5a-5d, 6a-6d provided to a front side of the support frame unit 2 whose back surface is fixed onto a mounting surface 20 of a package 19. In the vibrating section fixing surfaces B1, B2 of the mounting surface 20 to which back surfaces of vibration relaying sections A1, A2 of the support frame unit 2, which relay mechanical vibration of the support frame unit 2 when the mechanical vibration is propagated to the displacement parts from electrode pads 5a, etc. via the support frame unit 2, linear grooves 33a-33c, 34a-34c are formed in regions excluding regions directly under the electrode pads 5a. etc. and the respective grooves are filled with an adhesive 36.

Description

  The present invention relates to a MEMS device including a MEMS (micro electro mechanical systems) chip and a package that accommodates the chip.

  2. Description of the Related Art In recent years, as one form of an image display device, a projection display has been proposed in which light from a light source is deflected and projected onto a screen using an optical deflector, and an image is projected on the screen. Examples of the optical deflector include a MEMS optical deflector in which mechanical parts such as a mirror part and a piezoelectric actuator are integrally formed on a semiconductor substrate as a MEMS device using a semiconductor process or micromachine technology (eg, patent). Reference 1).

  The MEMS optical deflector includes a MEMS chip as a main body and a package for storing the MEMS chip. In the MEMS chip of the MEMS optical deflector described in Patent Document 1, the base end of the piezoelectric actuator is connected to and supported by a frame portion as a support portion, and the torque generated by the piezoelectric actuator is connected to the tip. This is transmitted to the base end of the (elastic beam), and the mirror portion provided at the tip of the torsion bar is driven to swing.

  When assembling the MEMS optical deflector from the MEMS chip and the package, the MEMS chip is placed on the placement surface of the package coated with an adhesive in the die bonding process, and in the next wire bonding process, the MEMS chip and the package The corresponding electrodes are connected to each other by wires. Usually, Au (gold) is used for the wires, and Al (aluminum) is used for the electrodes of the MEMS chip and the package. For this reason, the wire bonding machine applies ultrasonic waves to the wire and connects the wire to the Al electrode pad while removing the natural oxide film of the Al electrode pad of the MEMS chip that the tip of the wire hits.

JP 2008-40240 A

  In the MEMS chip of the MEMS optical deflector, a displacement allowance space exists inside the frame portion so as to allow swinging and displacement of the mirror portion and the displacement portion of the piezoelectric actuator. For this reason, compared with a normal semiconductor chip, since the ultrasonic power (vibration force) from the wire tip easily escapes to the displacement allowable space, the ultrasonic power applied to the wire is set stronger.

  On the other hand, in the MEMS optical deflector, in order to reciprocately swing the mirror portion around the axis with a larger swing angle, resonance of the mirror portion is used, and this resonance frequency is often 15 to 25 kHz. Therefore, when the frequency of the ultrasonic wave applied to the wire matches the resonant frequency itself of the MEMS chip or its harmonic frequency, the ultrasonic wave propagated on the chip excites the resonant structure, and near the root of the mirror part. There is a possibility that damage (break point 40 in FIG. 5 described later) occurs. If the ultrasonic power at the time of wire bonding is reduced in order to prevent this, sufficient bonding strength cannot be obtained, and another problem arises that the wire is disconnected during use.

  The object of the present invention is to displace the natural oxide film of the electrode on the MEMS chip side by ultrasonic waves while performing wire bonding in which ultrasonic waves are applied to the wires, and to displace the ultrasonic waves propagated from the wires. It is to provide a MEMS device capable of preventing breakage of a part.

  The present invention includes a MEMS chip having a support portion, a displacement portion that is movably supported by the support portion, and an electrode provided on a front side of the support portion, and a back surface of the support portion of the MEMS chip is made of resin. In a MEMS device comprising a package having a mounting surface fixed by an adhesive, a portion that passes through vibration in the support portion when mechanical vibration propagates from the electrode through the support portion to the displacement portion In the surface portion of the mounting surface to which the back surface of the electrode is fixed, a groove is formed in a portion excluding the portion directly below the electrode, and the groove is filled with the adhesive.

  According to the present invention, the ultrasonic wave propagating from the wire to the displacement portion through the electrode during wire bonding is a groove formed in the surface portion of the mounting surface to which the back surface of the vibration passing portion of the support portion is fixed. Damped by the adhesive inside. Thereby, the vibration of the ultrasonic wave propagating from the support portion to the displacement portion is attenuated to such an extent that the displacement portion is not damaged even if it propagates to the displacement portion. Moreover, since the groove | channel filled with the adhesive agent excludes the site | part of the surface part directly under an electrode, the vibration by the ultrasonic wave in an electrode is avoided attenuation | damping and is hold | maintained at a big value. As a result, the removal of the natural oxide film on the electrode on the MEMS chip side by the ultrasonic wave is appropriately executed, while the displacement portion is prevented from being damaged by the ultrasonic wave propagated from the wire.

  Preferably, the support portion includes a plurality of portions that pass through the vibration, and the groove is formed at a plurality of portions of the surface portion of the placement surface to which the back surface of the portion is fixed.

  According to this configuration, since the support portion and the displacement portion are coupled at a plurality of locations, even when the support portion has a plurality of portions that undergo vibration, the wire bonding is performed by applying ultrasonic waves to the wire. In addition, it is possible to prevent the displacement portion from being damaged by the ultrasonic wave propagated from the wire while appropriately removing the natural oxide film of the electrode on the MEMS chip side by the ultrasonic wave.

  Preferably, a plurality of the electrodes are provided along a vibration propagation path on a front side of a portion passing through vibration in the support portion, and the groove passes through the vibration between adjacent electrodes in the vibration propagation path. A surface portion of the mounting surface corresponding to the portion and a portion of the surface portion of the mounting surface corresponding to a portion passing through the vibration on the downstream side of the electrode disposed on the most downstream side in the vibration propagation path. One by one.

  According to this configuration, since the groove filled with the adhesive is provided one by one on the downstream side of the vibration propagation path of vibration in association with each electrode, the vibration from any electrode is vibrated. Force can be attenuated accurately.

  Preferably, a plurality of the electrodes are provided along a propagation path of the vibration on a front side of the portion of the support portion that passes through the vibration, and the groove is an electrode disposed on the most downstream side in the propagation path of the vibration. Only one is formed in a portion of the surface portion of the mounting surface corresponding to a portion passing through the vibration on the downstream side.

  According to this configuration, even if there are a plurality of electrodes in a portion that passes through vibration, only one adhesive-filled groove is required, so that the configuration can be simplified.

  Preferably, the support portion is formed as a frame-like support portion, the displacement portion is disposed in a space inside the frame-like support portion, and the groove crosses a vibration propagation path of the mechanical vibration. It is formed in the direction, and only one end side is exposed to the outside of the outer periphery of the frame-shaped support portion, and the portion other than the one end is hidden under the back surface of the frame-shaped support portion.

  According to this configuration, since the groove is exposed from below the frame-shaped support portion on the outer peripheral side of the frame-shaped support portion, the back surface of the frame-shaped support portion is pressed when the back surface of the frame-shaped support portion is pressed against the mounting surface. Excess adhesive sandwiched between the mounting surface and the mounting surface is introduced into the groove from the other end side, and flows in the groove toward the one end side. As a result, the flow of the adhesive to the inside of the annular frame is reduced, and the surplus adhesive that has flowed to the inside of the frame-like support portion can be prevented from adhering to the displacement portion. Further, the surplus adhesive at the exposed end of the groove scoops up a predetermined amount on the outer peripheral side of the frame-like support portion to form an appropriate fillet. As a result, the adhesion force of the MEMS chip to the package can be increased.

The perspective view of an optical deflector chip | tip. The front view of the MEMS optical deflector equipped with an optical deflector chip. Sectional drawing of the III-III arrow of FIG. Sectional drawing of the IV-IV arrow of FIG. The figure which shows the position of the vibration via part in a support frame part, and the vibration part fixing surface. The figure which shows a die-bonding process.

  FIG. 1 is a perspective view of the optical deflector chip 1, and FIG. 2 is a front view of a MEMS optical deflector 15 equipped with the optical deflector chip 1. For convenience of description of the configuration, when the MEMS optical deflector 15 is used, the side on which the MEMS optical deflector 15 emits scanning light is defined as the front side and the opposite side is defined as the back side, and the front side is defined as the MEMS optical deflector 15. The front side.

  1 and 2, the optical deflector chip 1 generally includes a support frame portion 2 and a displacement portion such as a mirror portion 9 supported by the support frame portion 2 (in FIG. 2, the right shoulder rises and the right shoulder descends). (The same applies to FIG. 5). In the front view, the support frame portion 2 has a square outer periphery and an inner periphery that is a circumference except for the projecting portions 4a and 4b. The inner space 3 is formed on the inner peripheral side of the support frame portion 2. The protrusions 4 a and 4 b are formed at positions where a predetermined diameter of the inner space 3 and the circular inner periphery of the support frame 2 intersect, and protrude by a predetermined amount toward the center of the inner space 3.

  The electrode pads 5a to 5d and 6a to 6d are made of, for example, Al (aluminum) material, and are arranged on the front side of the side portion of the support frame portion 2 perpendicular to the diameter of the inner space 3 passing through the protruding portions 4a and 4b. It is installed.

  The circular mirror portion 9 has its center aligned with the center of the inner space 3, and the torsion bars (elastic beams) 10a and 10b have a mirror portion 9 along a diameter orthogonal to the diameter of the inner space 3 passing through the protruding portions 4a and 4b. Protrudes from both sides. Hereinafter, for convenience of explanation, the direction of the diameter including the axis of the torsion bars 10a and 10b is referred to as “vertical direction”, and the direction of the diameter passing through the protrusions 4a and 4b is referred to as “lateral direction”. The vertical direction and the horizontal direction correspond to the vertical direction and the horizontal direction in the front view of FIG.

  The semicircular drive units 11a and 11b are disposed on both sides of the mirror unit 9 in the lateral direction, and both end portions as tip portions are coupled to both sides of the torsion bars 10a and 10b, and an intermediate portion as a base end portion is provided. It couple | bonds with the protrusion end of protrusion part 4a, 4b. In the semicircular type drive unit 11a, two portions from the base end portion to each tip end portion constitute piezoelectric actuators 12a and 13a, respectively. In the semicircular drive unit 11b, two portions from the base end portion to each tip end portion constitute piezoelectric actuators 12b and 13b, respectively. In the piezoelectric actuators 12a, 12b, 13a, and 13b, a piezoelectric film layer is formed closer to the front side than the back side. In the piezoelectric actuators 12a, 12b, 13a, and 13b, voltages from the electrode pads 5a to 5d and 6a to 6d are applied to the layers of the piezoelectric film, and the distal end side of the optical deflector chip 1 is directed to the front and back sides of the base end side. Displace.

  A sine wave voltage having the same frequency and amplitude is applied to the piezoelectric films of the piezoelectric actuators 12a, 12b, 13a, and 13b. The applied voltages between the piezoelectric actuators 12a and 12b are opposite to each other, the applied voltages between the piezoelectric actuators 13a and 13b are opposite to each other, and the applied voltages to the piezoelectric actuators 12a and 13a are in-phase with each other. The applied voltages of the actuators 12b and 13b are in phase with each other. As a result, the torsion bars 10a and 10b are driven in the same rotational direction at the respective time points from the semicircular drive units 11a and 11b on both sides in the lateral direction around the axis lines of the torsion bars 10a and 10b. It can be switched with. As a result, the torsion bars 10a and 10b reciprocally swing around the axis at a predetermined frequency.

  3 is a cross-sectional view taken along arrow III-III in FIG. 2, and FIG. 4 is a cross-sectional view taken along arrow IV-IV in FIG. In the cross-sectional views of FIGS. 3 and 4, the optical deflector chip 1 is omitted for the sake of simplicity, and only the entire outline is shown. The package 19 will be described with reference to FIGS.

  The package 19 is made of high-temperature fired alumina. The package 19 includes a center mounting surface (die bond surface) 20 as viewed from the front side, step portions 21 a and 21 b on both sides in the lateral direction with respect to the mounting surface 20, and the mounting surface 20 and step portions 21 a and 21 b. And surrounding frame portion 22. Of the placement surface 20, the step portions 21 a, 21 b and the frame portion 22, the frame portion 22 is located on the most front side, and the step portions 21 a, 21 b and the placement surface 20 are in a deep position from the frame portion 22 in this order. Yes.

  The electrodes 24a to 24d and 25a to 25d are arranged in a line at substantially equal intervals on the step portions 21a and 21b, respectively. The electrode pads 5a to 5d and 6a to 6d of the optical deflector chip 1 and the electrodes 24a to 24d and 25a to 25d of the package 19 are connected by a wire 30 using a predetermined bonding machine. At that time, the bonding machine applies ultrasonic waves to the wire 30 and removes the natural oxide films of the electrode pads 5a to 5d, 6a to 6d, 24a to 24d, and 25a to 25d with the tip of the wire 30, while the wire 30 Are fixed to the electrode pads 5a to 5d, 6a to 6d, 24a to 24d, and 25a to 25d. Although the electrode pads 5a to 5d and 6a to 6d receive the ultrasonic wave from the wire 30 for a short time, the ultrasonic wave from the wire 30 propagates into the support frame portion 2 via the electrode pads 5a to 5d and 6a to 6d. To do.

  The straight grooves 33 a to 33 c and 34 a to 34 c are formed on the mounting surface 20 along the side of the mounting surface 20 on the side of the step portions 21 a and 21 b in the front view of the MEMS optical deflector 15. Details of the structures of the straight grooves 33a to 33c and 34a to 34c will be described later. The adhesive 36 is filled in the linear grooves 33a to 33c and 34a to 34c. The adhesive 37 (see FIG. 6C) is applied to the portion of the mounting surface 20 to which the back surface of the support frame 2 is fixed, and the back surface of the support frame 2 is mounted. It adheres to the surface 20.

  FIG. 5 shows the positions of the vibration passing portions A 1 and A 2 in the support frame portion 2. As described above, at the time of wire bonding between the electrode pads 5a to 5d and 6a to 6d of the optical deflector chip 1 and the electrodes 24a to 24d and 25a to 25d of the package 19 by the bonding machine, the electrode pads 5a to 5d and 6a to Ultrasonic waves propagate from the wire 30 to 6d. The ultrasonic waves further reach the mirror unit 9 via the support frame 2, the semicircular drive units 11a and 11b, and the torsion bars 10a and 10b in order.

  The support frame part 2, the semicircular type drive parts 11a and 11b, and the torsion bars 10a and 10b are ultrasonic (mechanical vibration) applied from the wire 30 to the electrode pads 5a to 5d and 6a to 6d at the time of wire bonding. Configure the vibration propagation path. The vibration passing portions A1 and A2 are portions constituting an ultrasonic vibration propagation path in the support frame portion 2, and are defined as portions having a back surface fixed to the placement surface 20 in the support frame portion 2.

  Furthermore, the vibration portion fixing surfaces B1 and B2 are defined as surface portions on the mounting surface 20 side on which the back surfaces of the vibration passing portions A1 and A2 are fixed. The vibration unit fixing surfaces B1 and B2 coincide with the range of the placement surface 20 surrounded by the contour lines of the vibration passing portions A1 and A2 when the MEMS optical deflector 15 is viewed from the front.

  The protrusions 4a and 4b are parts of the support frame 2 and are part of the ultrasonic vibration propagation path. As can be understood from FIG. 1, the protrusions 4a and 4b are semicircular drive units. 11a, 11b, etc. The thickness is almost the same as that of the displacement portion, and the back surface thereof is not fixed to the mounting surface 20 but is lifted from the mounting surface 20. Therefore, the protrusions 4a and 4b are excluded from the vibration passing portions A1 and A2.

  When the protrusions 4a and 4b have the same thickness as the other parts of the support frame 2 and the back surfaces of the protrusions 4a and 4b are fixed to the mounting surface 20, the protrusions 4a and 4b also vibrate. It is included in the transit parts A1 and A2.

  A total of four ultrasonic vibration propagation paths are formed in the support frame 2. The first vibration propagation path is a path that travels from the electrode pads 5a and 5b to the protrusion 4a, the second vibration propagation path is a path that travels from the electrode pads 5d and 5c to the protrusion 4a, and the third vibration propagation path is The fourth vibration propagation path is a path that travels from the electrode pads 6d and 6c to the protrusion 4b. The first and second vibration propagation paths overlap at the protrusion 4a, and the third and fourth vibration propagation paths overlap at the protrusion 4b.

  The frequency of the ultrasonic wave applied to the wire 30 is not single, but is distributed in a predetermined frequency range. If there is a frequency that coincides with the resonance frequency of the mirror portion 9 or a higher-order mode frequency within the predetermined frequency range, the vibration of the support frame portion 2 from the electrode pads 5a to 5d and 6a to 6d. The ultrasonic wave propagated toward the mirror portion 9 via the via portions A1 and A2 is a resonance structure portion including the mirror portion 9 (in FIG. In some cases, the broken portion 40 near the base of the mirror portion 9 may be damaged. In addition, although the broken part 40 is illustrated in the vicinity of the root of the mirror portion 9 on the torsion bar 10 b side, the vicinity of the root on the torsion bar 10 a side may be broken before the broken part 40.

  The linear grooves 33a to 33c and 34a to 34c and the adhesive 36 filled therein contribute to the prevention of the occurrence of such breakage points 40.

  The straight grooves 33a to 33c and 34a to 34c are formed on the vibration portion fixing surfaces B1 and B2 of the mounting surface 20 in a direction crossing the propagation path of the mechanical vibration in the vibration passing portions A1 and A2. The straight grooves 33a, 33c, 34a, 34c are set at one end to the side on the stepped portion 21a, 21b side of the mounting surface 20 and at the other end are set to a position that fits inside the vibrating portion fixing surfaces B1, B2. As a result, the linear grooves 33a, 33c, 34a, and 34c are exposed from the bottom of the back surface of the vibration-passing portions A1 and A2 on one end side located outside the support frame portion 2, and the inner side of the support frame portion 2 except for one end side. Then, it is hidden under the back surface of the vibration-routed portions A1 and A2.

  The straight grooves 33b and 34b are set at one end to the side of the mounting surface 20 on the stepped portion 21a and 21b side, and at the other end beyond the inner edge of the vibration portion fixing surfaces B1 and B2, It reaches below 4b. Note that the straight grooves 33b and 34b are also set at positions where they are located inside the vibration portion fixing surfaces B1 and B2 at the other end, and thus, like the straight grooves 33a, 33c, 34a, and 34c, It can be exposed from the bottom of the back surface of the vibration-passing portions A1 and A2 on one end side located outside, and hidden behind the back surface of the vibration-passing portions A1 and A2 except for the one end side.

  The straight grooves 33a to 33c and 34a to 34c are formed at portions of the vibrating portion fixing surfaces B1 and B2 excluding the portions immediately below the electrode pads 5a to 5d and 6a to 6d. The straight grooves 33a, 33c, 34a, and 34c are associated with the electrode pads 5a, 5d, 6a, and 6d, respectively, and are disposed in the vibration propagation path of the ultrasonic waves (mechanical vibrations) in the vibration passing portions A1 and A2. , 5d, 6a, 6d and one range downstream thereof, that is, one in each range of the vibrating portion fixing surfaces B1, B2 corresponding to the range between the electrode pads 5b, 5c, 6b, 6c adjacent to the downstream side. It has been formed one by one.

  The straight grooves 33b and 34b respectively correspond to the ranges of the vibration passing portions A1 and A2 on the downstream side of the electrode pads 5b, 5c, 6b, and 6c as the most downstream electrode pads in the respective ultrasonic vibration propagation paths. One is formed in the range of the vibration portion fixing surfaces B1 and B2. The straight groove 33b is associated with the electrode pads 5b and 5c, and the straight groove 34b is associated with the electrode pads 6b and 6c.

  Wire bonding performed by applying ultrasonic waves to the wire 30 is performed after the die bonding step is completed. Filling the linear grooves 33a to 33c and 34a to 34c with the adhesive 36 is performed in a die bonding step. The die bonding process will be described with reference to FIG.

  In FIG. 6, (a) to (d) sequentially show the sub-processes of the die bonding process. In each of the sub-steps (a) to (d), the left is an arrow cross-sectional view of the package 19 at the same position as the IV-IV arrow cross-section of FIG. 2, and the right is a front view of the package 19. Yes.

  FIG. 6A shows the state of the package 19 at the start of the die bonding process, and the linear grooves 33a to 33c and 34a to 34c are empty.

In FIG. 6B, the adhesive 36 is filled in the linear grooves 33a to 33c and 34a to 34c by a dispenser. In this example, a silicone resin having a specific gravity of about 1.0 g / cm ³ and a viscosity of about 40 Pa · s was used as the adhesive 36.

  In FIG.6 (c), the adhesive agent 37 is apply | coated to the mounting surface 20 with a dispenser. The adhesives 36 and 37 have different application ranges and different sub-processes to be applied. Therefore, different reference numerals are used in FIG. 6, but the same materials are used. The application range is set to a range in which the back surface of the support frame portion 2 of the optical deflector chip 1 is pressed against the mounting surface 20, and has a “B” shape in accordance with the outer peripheral contour of the back surface of the mounting surface 20. Yes. The “B” -shaped application range in FIG. 6C is a range that is hidden under the back surface when the back surface of the support frame portion 2 is fixed to the placement surface 20.

  As can be seen from the right diagram in FIG. 6C, the inner end of the adhesive 36 is substantially equal to the inner peripheral line of the application range of the adhesive 37. As described above, the linear grooves 33a, 33c, 34a, 34c are set so that the outer ends thereof are exposed from the back surfaces of the vibration passing portions A1, A2. Accordingly, the outer end of the adhesive 36 filled in the linear grooves 33 a, 33 c, 34 a, 34 c is a position sufficiently protruding outward from the outer peripheral line of the application range of the adhesive 37.

  6D, the optical deflector chip 1 on the dicing tape (not shown) is picked up using a pyramid collet (not shown), and the mounting surface 20 of the package 19 to which the adhesive 37 is applied. The die is bonded to the predetermined position with an appropriate pressure. Since the outer ends of the straight grooves 33 a, 33 c, 34 a, 34 c are exposed from the back surfaces of the vibration passing portions A 1, A 2 of the support frame portion 2, the surplus adhesive 37 is supported on the mounting surface 20. As it is pressed against the back surface of the frame portion 2, it flows into the straight grooves 33a, 33c, 34a, and 34c from the inner end thereof, and the adhesive 36 in the straight grooves 33a, 33c, 34a, and 34c is exposed to the outer exposed end portion. Push towards the. As a result, when the support frame portion 2 of the optical deflector chip 1 is pressed against the mounting surface 20 of the package 19, the back surface of the vibration passing portions A 1 and A 2 and the vibration portion fixing surfaces B 1 and B 2 of the mounting surface 20 The force of the adhesive 37 sandwiched therebetween flowing toward the inside is weakened, and the amount of flow toward the inside is reduced.

  Although not shown, an annular rib is formed on the back side of the mirror unit 9 in order to prevent distortion of the mirror unit 9. Since the lower end of the annular rib approaches the placement surface 20, there is a possibility that excess adhesive 37 that has flowed inside the placement surface 20 adheres to the annular rib and fixes the annular rib to the placement surface 20. There is. The decrease in the fluid force of the adhesive 37 inside the support frame portion 2 contributes to the prevention of the excessive adhesive 37 from adhering to the displacement portion such as the annular rib.

  On the other hand, the adhesive 36 pushed out in the straight grooves 33a to 33c and 34a to 34c toward the outer exposed end portion crawls up the outer peripheral edge of the support frame portion 2 from the exposed end portion by an appropriate amount, Form. This fillet increases the bonding strength of the support frame 2 to the mounting surface 20.

  Although illustration is omitted, after the sub-process of FIG. 6D, there is a sub-process in which the optical deflector chip 1 is left in an electric oven heated to 150 ° C. together with the package 19 for 4 hours. By this sub-process, the adhesives 36 and 37 are completely cured. Due to the effect of the fillet, positional deviation of the optical deflector chip 1 from the end of die bonding until the resin is completely cured is suppressed.

  Light is applied to the package 19 by wire bonding between the electrode pads 5a to 5d and 6a to 6d of the optical deflector chip 1 and the electrodes 24a to 24d and 25a to 25d of the package 19 with Au (gold) wires 30. The mounting of the deflector chip 1 is completed. In the wire bonding, the ultrasonic wave applied to the wire 30 removes the Al oxide film of the electrode pads 5a to 5d and 6a to 6d, enters the support frame 2, and passes through the vibration passing parts A1 and A2 to make a semicircle. Propagating toward the circumferential drive units 11a and 11b. At that time, the vibration force is absorbed by the adhesive 36 in the linear grooves 33a to 33c and 34a to 34c. As a result, the vibration force propagating from the vibration passing portions A1, A2 to the semicircular type drive portions 11a, 11b via the protrusions 4a, 4b is at least less than the vibration force that generates the breaking point 40, It is weakened and generation | occurrence | production of the broken part 40 is prevented effectively.

  On the back surface of the package 19, electrode pads (not shown) connected to the front side electrodes 24 a to 24 d and 25 a to 25 d by internal wiring are provided. After the wire bonding step, the flexible cable is crimped to the back electrode pad and connected to the circuit board, or directly connected to the printed board to be electrically connected to the circuit board.

  When a sine wave signal having a frequency of 25 kHz and a voltage of 0 to 15 V is applied to the piezoelectric actuators 12a, 12b, 13a, and 13b of the MEMS optical deflector 15 mounted according to the above procedure, the mechanical action of the mirror unit 9 is performed. A deflection angle of ± 12 ° was observed. This corresponds to a sufficient angle as a MEMS optical deflector for projector use. Although indirect, it was proved that there was no degradation of the device structure due to the ultrasonic wave during wire bonding. When the positional relationship between the center of the mirror portion 9 of the optical deflector chip 1 and the center of the package 19 was measured, the degree of translational deviation was within ± 50 μm in both the horizontal and vertical directions, and the degree of rotational deviation was ± 0.1 °. Very good value was shown. It was also verified that due to the effect of the fillet of the adhesive 36, there was almost no displacement during curing of the adhesive 36.

  The MEMS light deflector 15 is mounted on, for example, a projection display that projects an image on a screen, a vehicle headlamp, or the like. In that case, a light beam is emitted toward a mirror unit 9 from a predetermined light source (not shown) arranged facing the front side of the MEMS optical deflector 15. On the other hand, the MEMS optical deflector 15 is supplied with a drive voltage having a frequency equal to the resonance frequency of the resonance structure including the mirror unit 9 to the piezoelectric elements of the piezoelectric actuators 12a, 12b, 13a, and 13b in a corresponding phase. Oscillates reciprocally around the axis of rotation at the resonance frequency with the axis of the torsion bars 10a, 10b as the axis of rotation. As a result, the mirror unit 9 emits reflected light that scans the incident light from the light source around the rotation axis as scanning light. The scanning light then travels toward the screen via an optical device such as a beam splitter.

  The embodiments of the present invention have been described. The MEMS optical deflector 15 is an example of the MEMS device of the present invention. The mirror part 9, the torsion bars 10a and 10b, and the semicircular type drive parts 11a and 11b are examples of a displacement part that is movably supported by the frame part 2 as a support part or a frame-like support part. The straight grooves 33a to 33d and 34a to 34d are examples of the grooves of the present invention. The electrode pads 5a to 5d and 6a to 6d are examples of the electrode of the present invention. The electrode pads 5b, 5c, 6b, and 6c are examples of electrodes disposed on the most downstream side in the vibration propagation path.

  The present invention is not limited to the embodiments and can be implemented with various modifications. For example, in the embodiment, the MEMS optical deflector 15 has been described as the MEMS device, but the present invention is also applicable to other MEMS devices in which the MEMS chip has a support portion and a displacement portion.

  In the embodiment, the support frame portion 2 as a support portion of the MEMS chip has a frame shape, but the support portion of the MEMS chip of the present invention may not have a frame shape.

  In the embodiment, the linear grooves 33a, 33c, 34a, 34c are formed in association with the electrode pads 5a, 5d, 6a, 6d, but the linear grooves 33a, 33c, 34a are left, leaving the linear grooves 33b, 34b. , 34c can be omitted. Because, in wire bonding, the wire bonding machine does not connect a plurality of wires 30 together, but connects them to the corresponding electrodes one by one, so it corresponds to the most downstream range of the vibration propagation path in the support frame 2 This is because the straight grooves 33b and 34b to be used can be used as a common groove for the electrode pads 5a to 5d and 6a to 6d.

DESCRIPTION OF SYMBOLS 1 ... Optical deflector chip, 2 ... Support frame part (support part and frame-shaped support part), 3 ... Inner space, 5a-5d, 6a-6d ... Electrode pad, 9 ... Mirror part (displacement part), 10a, 10b ... Torsion bar (displacement part), 11a, 11b ... Semicircular drive part (displacement part), 12a, 12b, 13a, 13b ... Piezoelectric actuator ( Displacement part), 15 ... MEMS optical deflector (MEMS device), 19 ... Package, 20 ... Mounting surface, 30 ... Wire, 33a-33d, 34a-34d ... Linear groove ( Groove), 36... Adhesive, A1, A2... Vibration passing portion, B1, B2.

Claims (5)

A MEMS chip having a support portion, a displacement portion that is movably supported by the support portion, and an electrode provided on a front side of the support portion;
In a MEMS device comprising: a package having a mounting surface on which a back surface of the support portion of the MEMS chip is fixed by a resin adhesive;
When the mechanical vibration propagates from the electrode to the displacement portion via the support portion, the back surface of the portion that passes through the vibration in the support portion is fixed. A MEMS device, wherein a groove is formed in a portion other than the portion, and the groove is filled with the adhesive. The MEMS device according to claim 1, wherein
The support portion has a plurality of portions that pass through the vibration,
The said groove | channel is formed in the several site | part of the surface part of the said mounting surface to which the back surface of this part is fixed, The MEMS device characterized by the above-mentioned. The MEMS device according to claim 1 or 2,
A plurality of the electrodes are provided along the propagation path of the vibration on the front side of the portion of the support portion through the vibration,
The groove includes a surface portion of the mounting surface corresponding to a portion passing through the vibration between adjacent electrodes in the vibration propagation path, and a downstream side of the electrode disposed on the most downstream side in the vibration propagation path. One MEMS device is formed in each part of the surface portion of the mounting surface corresponding to the portion passing through the vibration. The MEMS device according to claim 1 or 2,
A plurality of the electrodes are provided along the propagation path of the vibration on the front side of the portion of the support portion through the vibration,
Only one groove is formed in a portion of the surface portion of the mounting surface corresponding to a portion passing through the vibration on the downstream side of the most downstream electrode in the vibration propagation path. A featured MEMS device. The MEMS device according to any one of claims 1 to 4,
The support part is formed as a frame-like support part,
The displacement part is disposed in a space inside the frame-shaped support part,
The groove is formed in a direction crossing the vibration propagation path, and is exposed to the outside of the outer periphery of the frame-shaped support portion only at one end side, and the portion other than the one end side is hidden under the back surface of the frame-shaped support portion The MEMS device characterized by the above-mentioned.