JP6190703B2 - Optical deflector and optical deflector chip - Google Patents

Description

  The present invention relates to an optical deflector and an optical deflector chip that are manufactured using MEMS (Micro-Electro-Mechanical Systems) technology.

  An optical deflector chip manufactured using MEMS technology has a movable part including a light reflecting surface on the front side, a displacement space that supports the movable part so as to move, and opens on the back side to displace the movable part. Is formed on the inner peripheral side (e.g., Patent Documents 1 and 2).

  The optical deflector chip is housed in a package and constitutes an optical deflector together with the package (eg, Patent Document 3). For example, the package has a role of preventing foreign matter from adhering to or sandwiching between the mirror surface and the movable part.

  FIG. 9 schematically shows the structure of a conventional optical deflector. The illustrated optical deflector 125 includes an optical deflector chip 101 and a package 126 that stores the optical deflector chip 101 in a storage space 127.

  The optical deflector chip 101 includes a mirror part 102, an inner frame part 103 surrounding the mirror part 102, an outer frame part 104 surrounding the inner frame part 103, and between the mirror part 102 and the inner frame part 103. The inner frame portion 103 interposed between the inner frame portion 103 and the outer frame portion 104, and the inner frame portion 103 between the inner frame portion 103 and the first frame portion. An outer actuator section that reciprocates around a second rotation axis that is orthogonal to the rotation axis.

  The package 126 has, at the bottom 139, a central recess 141 and a peripheral seat 140 that surrounds the recess 141. The recess 141 has a bottom surface 142 and a peripheral wall 143 that stands up from the periphery of the bottom surface 142. The extension space 145 is formed by the bottom surface 142 of the concave portion 141 and the peripheral wall 143, and is aligned with the back side opening of the displacement allowable space 135 of the optical deflector chip 101 and forms a continuous space behind the displacement allowable space 135.

  The back surface of the outer frame portion 104 is flat to match the surface of the seat portion 140 of the package body 128. The back surface of the outer frame portion 104 is placed on the seat portion 140 such that the inner peripheral edge thereof is aligned with the inner peripheral edge of the seat portion 140, and is adhered to the bottom portion 139 by a die attach agent 160 interposed between the seat portion 140. The

JP 2005-148459 A JP 2008-40240 A JP 2003-243550 A

  In the conventional optical deflector 125 described above, when the optical deflector chip 101 is fixed to the bottom portion 139 of the package body 128, the die attach agent 160 is applied to the portion of the seat portion 140 on which the outer frame portion 104 is placed. . Thereafter, the outer frame portion 104 is pressed by the seat portion 140 and the back surface thereof is bonded to the seat portion 140 by the die attach agent 160. At that time, the die attach agent 160 protrudes to the outside of the outer periphery of the outer frame portion 104, and the protruding portion forms a mountain hem-like fillet 161 on the outer periphery side of the outer frame portion 104. Further, the die attach agent 160 protrudes inside the inner periphery of the outer frame portion 104, and the protruding portion forms a ball-shaped fillet 162 on the inner periphery side of the outer frame portion 104.

  The outer peripheral edge portion of the inner frame portion 103 farthest from the second rotation axis is reciprocated around the second rotation axis, and the inner periphery side of the outer frame portion 104 is squeezed while the optical deflector chip 101 Since it is displaced in the front and back direction, if a large ball-shaped fillet 162 is formed, the ball-shaped fillet 162 may collide with the ball-shaped fillet 162 and may be damaged, or reciprocal rotation around the second rotation axis may be hindered.

  As a countermeasure, the diameter of the recess 141 is increased so that the outer frame portion 104 has a structure like a ridge protruding a predetermined amount from the seat portion 140 on the inner peripheral side, and a ball-shaped fillet 162 is formed under the heel. It is conceivable that the protruding end of the ball-shaped fillet 162 does not protrude beyond the inner periphery of the outer frame portion 104 into the displacement range of the inner frame portion 103. However, in this structure, there is a problem that the adhesion area between the outer frame portion 104 and the seat portion 140 is reduced, and the adhesion force is reduced.

  An object of the present invention is to prevent a situation in which an adhesive protrudes inward and obstructs displacement of a movable portion of an optical deflector chip while ensuring a desired adhesion area between the optical deflector chip and a package. An optical deflector and an optical deflector chip that can be provided.

  An optical deflector according to the present invention includes an optical deflector chip and a package in which the optical deflector chip is disposed. The optical deflector chip includes a movable part including a light reflecting surface on a front side, and the movable part is displaced. And a support part that forms a displacement space that opens on the back side to displace the movable part on the inner peripheral side, and the package is formed at a position facing the back side of the displacement space. And a seat portion formed at a position where the back surface portion of the support portion of the optical deflector chip hits, and the back surface portion of the support portion is bonded to the seat portion in the front-back direction. The outer peripheral side back portion and the inner peripheral side back portion bonded to the peripheral wall of the recess in a direction perpendicular to the front and back direction.

  According to the present invention, the optical deflector chip and the package are provided between the outer periphery side back portion of the back surface portion of the optical deflector chip and the seat portion of the package, and the inner periphery side back portion of the back surface portion of the optical deflector chip. Since it adhere | attaches between the surrounding walls of a recessed part, a desired adhesion area is ensured.

  According to the present invention, the inner peripheral back portion of the back surface portion of the optical deflector chip faces the peripheral wall of the recess in a direction perpendicular to the front and back directions. Therefore, when the adhesive applied to the seat is pushed inward along with the pressing from the outer peripheral side of the back surface of the optical deflector chip, the direction changes from the inner side to the direction along the peripheral wall of the recess. To do. As a result, it is possible to prevent the adhesive from protruding beyond the support portion inwardly in the direction perpendicular to the front and back directions, and to prevent a situation in which the displacement of the movable portion is hindered.

  In the optical deflector of the present invention, the seat portion is formed at a top portion of an upright portion that is bonded to a bottom portion of a storage space in which the optical deflector chip is stored, and the concave portion is an inner periphery of the upright portion. It is preferable that it is formed on the side.

  According to this configuration, the support portion of the optical deflector chip is fixed with the upright portion interposed between the support portion and the bottom portion. When the inner peripheral side back portion of the support portion is fitted to the inner peripheral side of the standing portion, the movable portion of the optical deflector chip easily collides with the bottom portion when the front and back direction dimensions of the back surface portion and the bottom portion are reduced. In order to avoid this, when the concave portion is formed in the bottom portion, if the depth of the concave portion is increased, the strength of the bottom portion is lowered. However, the height of the standing portion is increased by interposing the upright portion. Thus, the above problem can be solved.

  In the optical deflector of the present invention, the movable part of the optical deflector chip is disposed inside a mirror part having the light reflecting surface on the front side and an outer frame part that surrounds the mirror part and serves as the support part. An inner frame portion provided, an inner actuator portion interposed between the inner frame portion and the mirror portion, for reciprocatingly rotating the mirror portion around a first rotation axis, and the first rotation axis. The inner frame portion is disposed on both sides of the inner frame portion and on the inner peripheral side of the outer frame portion in the direction of the second rotation axis perpendicular to each other, and is interposed between the outer frame portion and the inner frame portion. And an outer actuator portion that reciprocally rotates around the second rotation axis.

  According to this configuration, in order to reduce the size of the optical deflector chip, the portion of the inner frame portion that is farthest from the second rotation axis is displaced in the front-back direction at a location that is extremely close to the inner periphery of the outer frame portion. At the same time, it becomes the place of maximum displacement and is displaced to the vicinity of the back surface of the support portion. However, due to the structure in which the inner peripheral side back portion of the back surface protrudes in the back direction from the outer peripheral side back portion and the peripheral wall of the recess fits, the protruding portion of the adhesive is the back side of the inner peripheral side back portion of the back surface portion. This prevents the adhesive from protruding from the inner peripheral side back portion to the inside. Thereby, it can prevent effectively that the maximum displacement part of an inner side frame part collides with an adhesive agent at the time of a maximum displacement.

  Next, an optical deflector chip according to the present invention has a movable part including a light reflecting surface on the front side, and a displacement space that opens on the back side to support the movable part and move the movable part. A support portion formed on the inner peripheral side, and a rear surface portion of the support portion is an outer peripheral side back portion that is a plane perpendicular to the front and back direction, and an inner portion that protrudes in the back direction from the outer peripheral side back portion. And a circumferential back portion.

  According to the optical deflector chip of the present invention, the back surface portion of the support portion includes the outer peripheral side back portion and the inner peripheral side back portion that can be bonded to the seat portion of the package and the peripheral wall of the recess. A desired bonding area is ensured.

  In addition, the adhesive between the seat when bonded to the package moves to the back along the peripheral wall of the recess without protruding inward, so the protruding portion of the adhesive is movable The situation which disturbs the displacement of a part can be prevented.

The perspective view of an optical deflector chip | tip. The structure diagram of an optical deflector. Sectional drawing of an outer side frame part. The manufacturing process figure of the 1st range of an optical deflector chip | tip. The manufacturing process figure of the 2nd range of an optical deflector chip | tip. The manufacturing process figure of the 3rd range of an optical deflector chip | tip. The manufacturing process figure which attaches an optical deflector chip | tip to a package. Explanatory drawing when attaching an optical deflector chip | tip to another package. Explanatory drawing of the conventional optical deflector.

  The optical deflector chip according to the embodiment will be described with reference to FIG. As will be described later, the optical deflector chip 1 is manufactured using MEMS technology. The optical deflector chip 1 includes a mirror part 2 disposed at the center, a rectangular inner frame part 3 surrounding the mirror part 2 from the outside, and a rectangular outer frame part 4 surrounding the inner frame part 3 from the outside. Yes.

  For convenience of explanation, the vertical direction and the horizontal direction of the optical deflector chip 1 are defined as a direction parallel to the short side and a direction parallel to the long side of the outer frame part 4, respectively. In FIG. 1, the diagonally lower left-upper right direction is the vertical direction of the optical deflector chip 1, and the diagonally upper left-lower diagonal direction is the lateral direction of the optical deflector chip 1. Further, the side on which the light deflector chip 1 enters and reflects light is defined as the front side of the light deflector chip 1, and the side opposite to the front side is defined as the back side of the light deflector chip 1.

  The optical deflector chip 1 has a symmetric structure with respect to a vertical center line passing through the center of the mirror portion 2. The pair of torsion bars 5 are arranged on both sides in the vertical direction with respect to the mirror part 2 with their axes aligned in the vertical direction, and the tip side is coupled to the mirror part 2. The base end side of the torsion bar 5 is coupled to the central portion on the inner peripheral side of the lateral side of the inner frame portion 3. The base end side of the torsion bar 5 may be separated from the inner periphery of the inner frame portion 3 without being coupled to the inner periphery of the inner frame portion 3.

  For each torsion bar 5, one inner actuator 6 is disposed on each side in the lateral direction. The inner actuator 6 has a linear shape in the lateral direction, and is coupled to the inner periphery of the inner frame portion 3 and the torsion bar 5 on the proximal end side and the distal end side, respectively. The coupling position of the inner actuator 6 to the torsion bar 5 is set to a vertical position away from the peripheral edge of the mirror unit 2 by a predetermined distance.

  The inner actuator 6 is a cantilever type piezoelectric actuator using a piezoelectric film. When the optical deflector chip 1 is incorporated in an optical scanner or the like, the inner actuators 6 on both sides in the lateral direction are driven by an applied voltage from a controller (not shown) of the optical scanner. The applied voltage has the same frequency as the resonance frequency of the structural portion including the mirror portion 2 and the torsion bar 5 (hereinafter referred to as “first frequency”), and is opposite to each other in the inner actuators 6 on both lateral sides. The phase is

  As a result, the cantilevers as the inner actuators 6 on both sides in the lateral direction increase or decrease the amount of deflection in opposite phases, and drive the torsion bar 5 in the same rotational direction around the first rotational axis. The first rotation axis coincides with the axis of the torsion bar 5 and is set to pass through the center of the mirror unit 2.

  Since the control voltage supplied as the applied voltage of the cantilever from the controller (not shown) to the inner actuator 6 increases and decreases at the first frequency, the mirror unit 2 reciprocates around the first rotation axis at the first frequency. Rotate.

  The pair of outer actuators 7 are disposed on both lateral sides with respect to the inner frame portion 3. Each outer actuator 7 has a plurality (four in the illustrated example) of cantilevers 13 coupled in series in a meander pattern, and the base end side is one end side of the vertical side portion of the outer frame portion 4 (the lower side in FIG. 1). The front end side is coupled to one end side of the vertical side portion of the inner frame portion 3.

  Each cantilever 13 has a structure operable as one actuator. Therefore, the entire action of the outer actuator 7 is a cooperative action of the four cantilevers 13 as the four actuators.

  In each of the outer actuators 7, the cantilevers 13 are arranged side by side with the longitudinal direction aligned with the longitudinal direction of the optical deflector chip 1, and the cantilevers 13 that are adjacent in the lateral direction are mutually connected at the end portions via the folded portions. It is connected. Accordingly, the outer actuator 7 has a structure in which a plurality of cantilevers 13 are coupled in series.

  When numbers 1 to 4 are assigned to the plurality of cantilevers 13 of each outer actuator 7 in the order of arrangement from the proximal end side to the distal end side of the outer actuator 7, the optical scanner controls the piezoelectric layer 80 described later of each cantilever 13. By supplying a predetermined applied voltage from a container (not shown), the amount of bending of the cantilevers 13 increases and decreases in the same phase between the odd-numbered cantilevers 13 and between the even-numbered cantilevers 13. Further, the amount of bending of the odd-numbered cantilever 13 and the amount of bending of the even-numbered cantilever 13 increase or decrease in opposite phases. Thereby, the outer actuators 7 on both sides in the lateral direction with respect to the mirror part 2 cooperate to reciprocately rotate one end side in the longitudinal direction of the inner frame part 3 around the second rotation axis. The second rotation axis is a straight line parallel to the lateral direction of the optical deflector chip 1, and is orthogonal to the first rotation axis at the center of the mirror unit 2.

  The electrode pads 8 and 9 are respectively provided on the front side surfaces of one of the outer frame portions 4 and the other vertical side portion. The electrode pad 8 is connected to electrode terminals in the inner actuator 6 and the outer actuator 7 disposed on the electrode pad 8 side with respect to the mirror part 2 via metal wiring, and the electrode pad 9 is connected to the mirror part 2. The electrode terminals in the inner actuator 6 and the outer actuator 7 arranged on the electrode pad 9 side are connected via metal wiring. The electrode pads 8 and 9 are connected to the terminals of the package 26 in which the optical deflector chip 1 is housed as bonding pads via bonding wires (not shown).

  The overall operation of the optical deflector chip 1 will be briefly described. The mirror unit 2 reciprocally rotates around the first and second rotation axes at the first and second frequencies by the operation of the inner actuator 6 and the outer actuator 7, respectively, and a light source (not shown) (eg, laser light source). ) From a certain direction is incident on the mirror surface on the front side of the mirror unit 2 from the front side. The mirror unit 2 reflects the light at an angle corresponding to the rotation angle around the first and second rotation axes on the mirror surface and emits the light to the front side.

  The light emitted from the optical deflector chip 1 becomes scanning light that reciprocates in a predetermined scanning angle range in the horizontal direction and the vertical direction at a predetermined frequency. In general, the second frequency is lower than the first frequency. Further, the resonance of the structural portion including the mirror portion 2 and the torsion bar 5 is not used for the reciprocating rotation of the mirror portion 2 around the second axis by the outer actuator 7 at the second frequency. Therefore, the rotational driving force of the mirror unit 2 by the outer actuator 7 needs to be larger than the rotational driving force of the mirror unit 2 by the inner actuator 6.

  The optical deflector chip 1 is typically installed with its vertical and horizontal directions aligned in the vertical and horizontal directions, respectively. In this case, the reflected light from the mirror unit 2 is reciprocated in the horizontal direction by the rotation of the mirror unit 2 around the first rotation axis. Further, the reflected light from the mirror part 2 is reciprocated in the vertical direction by the rotation of the mirror part 2 around the second rotation axis. Thereby, the reflected light from the optical deflector chip 1 is emitted as light for scanning the irradiation destination vertically and horizontally.

  The optical deflector chip 1 is mounted on an optical scanner together with its light source. The optical scanner is installed in, for example, a projector, a barcode reader, a laser printer, a laser head amplifier, or a head-up display.

  FIG. 2 is a cross-sectional view showing the internal structure of the optical deflector 25. FIG. 2 is a cross-sectional view passing through the center of the mirror portion 2 and perpendicular to the second rotation axis.

  The optical deflector 25 includes an optical deflector chip 1 and a ceramic package 26 that houses the optical deflector chip 1. The package 26 includes a package main body 28 that forms a storage space 27 for storing the optical deflector chip 1 inside, and a lid 29 that seals the opening side of the package main body 28. The inside of the storage space 27 after being sealed by the lid 29 is, for example, in a reduced pressure state or a substantially vacuum state. The lid 29 has a transmission window 32 that transmits light at the center. Incident light traveling from the outside of the package 26 toward the mirror unit 2 and outgoing light as reflected light traveling from the mirror unit 2 to the outside of the package 26 pass through the transmission window 32.

  As described with reference to FIG. 1, the movable part such as the mirror part 2 of the optical deflector chip 1 reciprocates around the second rotation axis by the action of the outer actuator 7. As a result, each part of the movable portion is reciprocally displaced in the front and back direction (corresponding to the up and down direction in FIG. 2). The center of the light reflecting surface of the mirror part 2 is held at the same position in the front and back direction even during the displacement of the movable part in the front and back direction. The movable portion is in a stationary state while the optical deflector chip 1 is not operating, and is in a position (hereinafter referred to as “neutral position”) that is substantially aligned with the center of the mirror portion 2 in the front and back direction.

  The back side space 35 is formed by the inner peripheral surface of the outer frame part 4, and allows the movable part to be displaced to the back side with respect to the neutral position in the front and back direction. In the movable part of the optical deflector chip 1, the displacement range in the front and back direction increases as the position is farther from the second rotation axis. Further, the closer the tip of the outer actuator 7 is, the more the amount of bending of the cantilever 13 is accumulated, and the displacement range in the front and back direction increases. As a result, the outer peripheral edge of the lateral side portion of the inner frame portion 3 is displaced in the front and back direction of the optical deflector chip 1 so as to graze the inner peripheral side of the lateral side portion of the outer frame portion 4, and the optical deflector chip. 1, the maximum displacement is in the front and back direction.

  The bottom 39 of the package body 28 includes a peripheral seat 40 and a central recess 41. The seat 40 is formed in a plane perpendicular to the front and back direction of the optical deflector chip 1. The recess 41 has a bottom surface 42 as the innermost portion in the package body 28 and a peripheral wall 43 that rises in the front direction from the periphery of the bottom surface 42.

  The extension space 45 is formed by the bottom surface 42 and the peripheral wall 43 of the recess 41, and forms a continuous space on the back side of the back side space 35. The maximum displacement portion of the inner frame portion 3 in the front and back direction of the optical deflector chip 1 may exceed the back surface of the outer frame portion 4 when it is displaced to the backmost side. There is a role to avoid collision with the bottom surface 42.

  FIG. 3 is a cross-sectional view when the outer frame portion 4 is cut along a plane parallel to the front and back direction of the optical deflector chip 1. The outer frame portion 4 has a surface 50, an outer peripheral surface 51, and an inner peripheral surface 52, and an outer peripheral side back surface 53, an inner peripheral side back surface 54, and an inner outer peripheral surface 55 on the back side. The inner peripheral back surface 54 protrudes from the outer peripheral back surface 53 to the back side in the front-back direction. For this reason, the inner peripheral surface 55 is formed between the inner peripheral edge of the outer peripheral back surface 53 and the outer peripheral edge of the inner peripheral back surface 54. Note that the outer peripheral surface 51 constitutes the outer peripheral surface with respect to the inner peripheral surface 55.

In FIG. 3, d1 is the dimension of the outer peripheral side back surface 53 in the vertical and horizontal directions of the optical deflector chip 1, d2 is the distance between the outer peripheral side back surface 53 and the inner peripheral side back surface 54 in the front and back direction, and d3 is the optical The dimensions of the longitudinal and lateral surfaces 50 of the deflector chip 1 are shown. Examples of dimensions are as follows.
d1: 200 [μm] or more, preferably 250 [μm].
d2: 200 [μm] or more.
d3: 500 [μm].

  According to the dimensions (examples) d1 and d2 above, when the optical deflector chip 1 is pressed against the outer peripheral side rear surface 53 of the outer frame portion 4 against the seat portion 40, the outer peripheral side rear surface 53 is recessed from the seat portion 40. It can prevent slipping into 41. The dimensions of the rectangular inner peripheral edge of the outer frame portion 4 in the optical deflector chip 1 of FIG. 1 are, for example, about 4 mm in length and about 10 mm in width.

  Returning to FIG. 2, the die attach agent 60 is applied along the peripheral edge of the seat 40 on the side of the recess 41 before fixing the optical deflector chip 1 to the bottom 39. The material of the die attach agent 60 is, for example, a resin such as epoxy resin or silicon resin, or AuSn eutectic paste. In the optical deflector chip 1, the inner peripheral surface 55 of the outer frame portion 4 is fitted inside the peripheral wall 43 of the concave portion 41, and the outer peripheral side rear surface 53 abuts against the seat portion 40 toward the bottom surface 42 of the concave portion 41. Pushed in.

  Thereby, the die attach agent 60 is sandwiched between the outer peripheral side back surface 53 and the seat portion 40, and is perpendicular to the front and back direction of the optical deflector chip 1 and on the concave portion 41 side and the opposite direction thereof, that is, Extruded inward and outward. The mountain hem-like fillet 61 is formed by a portion of the die attach agent 60 that protrudes outward from the seat portion 40 and the outer peripheral back surface 53, and adheres to the outer peripheral surface 51 and the seat portion 40.

  The portion of the die attach agent 60 pushed inward from between the outer peripheral side back surface 53 and the seat 40 abuts on the inner outer peripheral surface 55, and the direction is changed from the inner side to the back side of the optical deflector chip 1. Thereafter, it moves between the peripheral wall 43 and the inner peripheral surface 55 toward the bottom surface 42, is exposed from the inner peripheral side rear surface 54, and forms a ball-shaped fillet 62 on the bottom surface 42 side with respect to the inner peripheral side rear surface 54. .

  The ball-shaped fillet 62 has a predetermined size, but does not protrude inward from the inner peripheral surface 52. Moreover, since the outer side frame part 4 is adhere | attached by the die attach agent 60 in the outer peripheral side back surface 53 and the inner peripheral surface 55, sufficient adhesion area is ensured.

  The inner frame portion 3 reciprocally rotates around the second rotation axis passing through the center of the mirror portion 2, and at the time of the maximum displacement at the maximum displacement portion toward the back side, Displace to the back side. However, since the collision with the ball-shaped fillet 62 is avoided, the displacement of the movable part of the optical deflector chip 1 due to the die attach agent 60 is prevented.

  4 to 7 show the manufacturing process of the optical deflector 25 in order. 4 to 6 show the manufacturing process of the optical deflector chip 1 only. FIG. 7 shows a manufacturing process for incorporating the completed optical deflector chip 1 into the package 26. 4 to 7 schematically show the characteristics of the manufacturing process, and are different from the structure shown in FIG. 1 in detail.

  In each STEP of FIGS. 4 to 6, the mirror portion 2, the outer frame portion 4, the inner actuator 6 and the outer actuator 7 of the optical deflector chip 1 are not completed. , Symbols A1 to A4 are used.

  A1 indicates a mirror part forming range as a range of the mirror part 2 in the manufacturing process of the optical deflector chip 1. A2 indicates an inner actuator formation range as a range of the inner actuator 6 in the manufacturing process of the optical deflector chip 1. A3 indicates an outer actuator formation range as a range of the outer actuator 7 in the manufacturing process of the optical deflector chip 1. A4 indicates the outer frame portion forming range as the range of the outer frame portion 4 in the manufacturing process of the optical deflector chip 1.

  The manufacturing process of the optical deflector 25 will be described in order. In STEP1, an SOI (Silicon on Insulator) substrate 70 is prepared. The SOI substrate 70 includes an active layer 71 (also referred to as “SOI layer”) of single crystal silicon, an intermediate oxide film layer 72 of silicon oxide, and a handling layer 73 of single crystal silicon in order from the upper layer. This is a bonded substrate. As for the thickness of each layer, for example, the thickness of the active layer 71 is 5 to 100 [μm], the thickness of the intermediate oxide film layer 72 is 0.5 to 2 [μm], and the thickness of the handling layer 73 is 100 to 600 [μm]. is there.

  In STEP 2, the front surface (active layer 71 side) and the back surface (handling layer 73 side) of the SOI substrate 70 are oxidized by a thermal oxidation furnace (diffusion furnace) to form thermal silicon oxide films 74 and 75 (thermal oxide film formation processing). ). The thickness of the thermally oxidized silicon films 74 and 75 is, for example, 0.1 to 1 [μm].

  In STEP 3, the lower electrode layer 79, the piezoelectric layer 80, and the upper electrode layer 81 are sequentially formed on the surface of the SOI substrate 70 (active layer 71 side).

  First, in the lower electrode layer forming process of STEP 3, a lower electrode layer 79 made of a two-layer metal thin film is formed on the thermally oxidized silicon film 74 on the active layer 71 side of the SOI substrate 70. As a material of the lower electrode layer 79, titanium is used for the first (lower) metal thin film, and platinum is used for the second (upper) metal thin film. Each metal thin film is formed by, for example, sputtering or electron beam evaporation. The thickness of each metal thin film is, for example, about 30 to 100 [nm] for the first Ti layer and about 100 to 300 [nm] for the second Pt layer.

  Next, in the piezoelectric layer forming process of STEP 3, a piezoelectric layer 80 made of a single piezoelectric film is formed on the lower electrode layer 79. As a material of the piezoelectric layer 80, lead zirconate titanate (PZT) which is a piezoelectric material is used. The thickness of the piezoelectric film is, for example, about 1 to 10 [μm]. The piezoelectric film is formed by, for example, an ion plating method using reactive arc discharge. For the ion plating method using reactive arc discharge, specifically, the methods described in JP-A Nos. 2001-234331, 2002-177765, and 2003-81694 are used.

  In this reactive ion plating method using arc discharge plasma, a source metal is heated and evaporated in a high-density oxygen plasma generated in a vacuum vessel by a plasma gun, and each metal vapor is deposited in the vacuum vessel or on a semiconductor substrate. By reacting with oxygen, a piezoelectric film is formed on the semiconductor substrate. By using this method, a piezoelectric film can be formed at high speed even at a relatively low film formation temperature. In particular, when a piezoelectric film is formed by an arc discharge reactive ion plating method, a seed layer is formed as a foundation by, for example, a chemical solution deposition method (CSD (Chemical Solution Deposition) method). A piezoelectric film having characteristics can be formed.

  The piezoelectric film may be formed by, for example, a sputtering method or a sol-gel method. However, by using an ion plating method using reactive arc discharge, a thick film having excellent piezoelectric characteristics (piezoelectric characteristics equivalent to a bulk piezoelectric body) can be formed.

  Next, the upper electrode layer 81 made of a single metal thin film is formed on the piezoelectric layer 80 by the upper electrode layer forming process of STEP 3. As a material of the upper electrode layer 81, Pt or Au is used. The upper electrode layer 81 is formed by, for example, a sputtering method or an electron beam evaporation method. The thickness of the upper electrode layer 81 is, for example, about 10 to 200 [nm].

  In STEP 4, the shape of the upper electrode layer 81, the piezoelectric layer 80, and the lower electrode layer 79 is processed in the inner actuator formation range A2 and the outer actuator formation range A3 by shape processing. Thus, the upper electrode, the piezoelectric body, and the lower electrode as elements of the inner actuator 6 and the outer actuator 7 from the upper electrode layer 81, the piezoelectric layer 80, and the lower electrode layer 79 in the inner actuator formation range A2 and the outer actuator formation range A3. Is formed.

  Specifically, first, a resist material is patterned on the upper electrode layer 81 by using a photolithography technique. Next, dry etching is performed on the upper electrode layer 81 and the piezoelectric layer 80 by using a patterned resist material as a mask by using an RIE (Reactive Ion Etching) apparatus. Thereby, an upper electrode pad (upper wiring connection portion), an upper electrode, and a piezoelectric body are formed. At this time, upper electrode wirings (electrode wiring patterns) for connecting these upper electrode pads and the upper electrodes of the piezoelectric cantilevers constituting the inner actuator 6 and the outer actuator 7 are also formed.

  Similarly, a resist material is patterned on the lower electrode layer 79 by using a photolithography technique. Next, using the patterned resist material as a mask, dry etching is performed on the lower electrode layer 79 using an RIE apparatus. Thereby, a lower electrode pad (lower wiring connection portion) and a lower electrode are formed.

  In STEP 5, the thermal silicon oxide film 75 is removed and a hard mask is formed. Specifically, the entire surface of the SOI substrate 70 is protected with a thick film resist, and the thermally oxidized silicon film 75 on the rear surface handling layer 73 side is removed with buffered hydrofluoric acid (BHF). Then, a single Al thin film 84 is formed on the entire surface of the handling layer 73 on the back side of the SOI substrate 70. The Al thin film 84 is formed using, for example, a sputtering method or a vapor deposition method. Then, a resist material is patterned on the Al thin film 84 using a photolithography technique. Next, wet etching is performed on the Al thin film 84 using the patterned resist material as a mask. Thereby, a hard mask (the Al thin film 84 on the back surface side of the mirror part forming range A1 and the outer frame part forming range A4) used for dry etching by an ICP (Inductively Coupled Plasma) -RIE apparatus of STEP 7 described later is formed.

  In STEP 6, the shape of the active layer 71 is processed. First, a resist material is patterned using a photolithography technique, and using the patterned resist material as a mask, the silicon shape of the thermally oxidized silicon film 74 and the active layer 71 is processed using an ICP-RIE apparatus. The ICP-RIE apparatus is a dry etching apparatus used in micromachine technology, and is an apparatus capable of deeply digging silicon vertically. Thereby, the active layer 71 is removed in places other than A2 to A4.

  Further, in STEP 6, the intermediate oxide film layer 72 of the SOI substrate 70 is removed using an ICP-RIE apparatus in the mirror part formation range A1. Then, the mirror surface reflection film (the metal thin film 86 in the mirror part formation range A1) is formed by the reflection surface formation process. First, a single metal thin film 86 is formed on the handling layer 73 of the SOI substrate 70 exposed by removing the intermediate oxide film layer 72. As a material of the metal thin film 86, for example, Au, Pt, Ag, Al or the like is used. The metal thin film 86 is formed by using, for example, a sputtering method or a vapor deposition method. The thickness of the metal thin film 86 is, for example, about 10 to 500 [nm].

  Next, the shape of the metal thin film 86 is processed. Specifically, first, a resist material is patterned on the metal thin film 86 using a photolithography technique. Next, using the patterned resist material as a mask, dry etching is performed on the metal thin film 86 using an RIE apparatus. Thereby, the metal thin film 86 as a mirror surface reflecting film remains on the handling layer 73 of the SOI substrate 70 in the mirror part formation range A1.

  In STEP 7, using the hard mask formed in STEP 5, the silicon of the handling layer 73 is processed from the back surface of the SOI substrate 70 using an ICP-RIE apparatus. As a result, the back side of the piezoelectric cantilever support (the handling layer 73 in the inner actuator formation range A2 and the outer actuator formation range A3) and the outer side of the outer frame are once dug by about 200 [μm], and the first step dug portion 87 is formed. Form.

  In STEP 8, the back side of the mirror part formation range A1 and the outer frame part formation range A4 is patterned using a photolithography technique. Next, using the patterned resist material as a mask, the back side of the support of the inner actuator 6 and the outer actuator 7 (the active layer 71 of the inner actuator formation range A2 and the outer actuator formation range A3) is further dug down. Then, the second step dug portion 88 is formed from the first step dug portion 87 in the inner actuator formation range A2 and the outer actuator formation range A3.

  In STEP 9, the intermediate oxide film layer 72 of the SOI substrate 70 is removed by wet etching using buffered hydrofluoric acid (BHF). Thereby, the periphery of the mirror part 2, the torsion bar 5, the inner actuator 6, the outer actuator 7, and the inner frame part 3 is partially separated from the SOI substrate 70 to form the gap 89, and the driving of the inner actuator 6 and the outer actuator 7 and the rotation of the mirror part 2, the inner frame part 3 and the torsion bar 5 are made possible.

  In STEP 10, after the die attach agent 60 is applied to the inner peripheral portion of the seat portion 40 of the package body 28, the first step digging portion 87 on the back side of the outer frame portion 4 is fitted into the peripheral wall 43 of the recess 41 of the package body 28. The optical deflector chip 1 is pushed into the recess 41 so as to match. In addition, the 1st step dug-down part 87 of the back side of the outer side frame part 4 is corresponded in the space part formed of the outer peripheral side back surface 53 and the inner peripheral surface 55 in FIG.

  In STEP 11, the die attach agent 60 that was on the seat portion 40 in STEP 10 is pushed outward and inward to form a skirt-like fillet 61 and a ball-like fillet 62 on the seat 40 and the peripheral wall 43, respectively.

  FIG. 8 is an explanatory diagram of a process of attaching the optical deflector chip 1 to the package 90 made of metal CAN. The bottom portion 91 of the package 90 (corresponding to the bottom surface 42 of the package main body 28 of the package 26 in FIG. 2) is formed on a flat surface that is perpendicular to the front and back direction of the optical deflector chip 1.

  The annular upright member 93 has a flat surface and a back surface, and after the die attach agent 60 is applied to the back side, a predetermined portion of the bottom portion 91 (the seat 40 at the bottom 39 of the package body 28 of the package 26 in FIG. 2). (Corresponding to the peripheral portion on the concave portion 41 side). The front and back dimension of the annular upright member 93 is sufficiently longer than the dimension length d2 (see FIG. 3) of the inner outer peripheral surface 55.

  The extension space 94 is formed on the inner peripheral side of the annular upright member 93, has the same function as the extension space 45 (FIG. 2) of the package 26, and is fitted to the back side space 35 of the optical deflector chip 1 from the back side.

  In the optical deflector chip 1, the die attach agent 60 is applied to the surface side of the annular upright member 93, and then the first step digging portion 87 on the back side of the outer frame portion 4 is fitted to the inner peripheral wall of the annular upright member 93. In this way, it is pushed into the inner peripheral side of the annular upright member 93. Although not shown, the die attach agent 60 on the surface side of the annular upright member 93 has a mountain-like shape similar to that shown in STEP 11 of FIG. 7 after the optical deflector chip 1 is bonded to the annular upright member 93. The fillet 61 and the ball-shaped fillet 62 are formed on the top surface and the inner peripheral surface of the annular upright member 93.

  Also in the annular upright member 93, the die attach agent 60 that protrudes from between the outer frame portion 4 and the annular upright member 93 with the attachment of the optical deflector chip 1 to the annular upright member 93 is the inner peripheral wall of the outer frame portion 4. It is prevented from projecting inward beyond. As a result, obstruction of the front-back direction displacement of the movable part of the optical deflector chip 1 due to the ball fillet 62 (see STEP 11 in FIG. 7) is prevented.

  Since the comparison experiment which confirms the effect of this invention was conducted, the result is demonstrated. In the comparison experiment, the optical deflector 25 (FIG. 2) and the optical deflector 125 (FIG. 9) were compared. The optical deflector 25 is equipped with the optical deflector chip 1, and the optical deflector 125 is equipped with the optical deflector chip 101. The difference between the optical deflector chip 1 and the optical deflector chip 101 is the sectional outline of the outer frame portion 4 and the outer frame portion 104. That is, the cross-sectional contour of the outer frame portion 4 is that shown in FIG. 3, whereas the cross-sectional contour of the outer frame portion 104 is a rectangle shown in FIG. The structures other than the cross-sectional contours of the outer frame portion 4 and the outer frame portion 104 are the same in the optical deflector chip 1 and the optical deflector chip 101. Therefore, of the optical deflectors 25 and 125 used for the experimental results, specific numerical values and the like of the optical deflector 25 will be described.

  The resonance frequency (resonance frequency of the mass body of the mirror unit 2 and the torsion bar 5) as a frequency of reciprocating rotation of the mirror unit 2 around the first rotation axis is designed to be 15 [kHz]. At this time, the thickness of each layer of the SOI substrate 70 is 50 [μm] for the active layer 71, 2 [μm] for the intermediate oxide film layer 72, and 525 [μm] for the handling layer 73, and the thickness of the thermally oxidized silicon film 74 is It was set to 500 [nm]. The thickness of the lower electrode layer 79 (Ti / Pt) is 50 [nm] for Ti and 150 [nm] for Pt, the thickness of the piezoelectric layer 80 (PZT) is 3 [μm], and the upper electrode layer 81 ( The thickness of Pt) was 150 [nm].

  For this optical deflector 25, an AC voltage with a peak-to-peak voltage Vpp = 25 [V] and a frequency of 15 [kHz] is applied to the inner actuator 6 as a drive signal, and a peak-to-peak voltage Vpp = 25 [V] is applied to the outer actuator 7. An alternating voltage with a frequency of 60 [Hz] was applied as a drive signal. The inner actuator 6 was resonantly driven for horizontal axis scanning, and the outer actuator 7 was nonresonantly driven for vertical axis scanning. At this time, the maximum deflection angle ± 8 ° is obtained on the horizontal axis, and the maximum deflection angle ± 6 ° is obtained on the vertical axis.

  In the optical deflector 25, the dimension of the extension space 45 of the package 26 is the space on the back side of the optical deflector chip 1 with respect to the dimensions perpendicular to the front and back directions (the vertical and horizontal dimensions of the optical deflector chip 1). The size of 35 was expanded by twice as long as d3-d1 (d1, d3 refer to FIG. 3). Further, the depth of the concave portion 41 is set to a sufficient depth so that the movable portion of the optical deflector chip 1 does not contact.

  A silicon die attach agent was applied to the seat portion 40 of the package 26 as the die attach agent 60, and the outer frame portion 4 of the optical deflector chip 1 was placed and bonded by thermosetting.

  The electrode pads 8 and 9 of the optical deflector chip 1 and the electrodes previously arranged in the ceramic package 26 were wire-bonded by an Au wire and electrically connected.

  In the comparison experiment, the state of protrusion of the die attach agent 60 and the influence on the operation of the optical deflector were confirmed. In the contrast experiment, in the optical deflector 125, the die attach agent 60 protrudes uniformly inside the outer frame 104 of the optical deflector chip 101. In this case, when the optical deflector 125 is operated, as described with reference to FIG. 9, the ball-shaped fillet 162 comes into contact with the inner frame portion 103, and normal operation of the optical deflector 125 can be obtained. There wasn't. Specifically, the above characteristics were not obtained, and the deflection angle around the second rotation axis was greatly reduced.

  On the other hand, in the optical deflector 25, the protrusion of the die attach agent 60 inside the outer frame portion 4 of the optical deflector chip 1 did not occur as described with reference to FIG. Even if the amount of the die attach agent 60 to be applied is increased to some extent, the protrusion does not occur in the same manner. As a result, it was confirmed that no abnormal operation occurred even when the optical deflector 25 was operated.

  Embodiments of the present invention have been described. The optical deflector chip 1 is an example of the optical deflector chip of the present invention. The mirror part 2, the inner frame part 3, the inner actuator 6, and the outer actuator 7 are examples of the movable part of the present invention. The outer frame portion 4 is an example of a support portion of the present invention that supports the movable portion so as to move.

  The inner actuator 6 is an example of the inner actuator portion of the present invention that is interposed between the inner frame portion and the mirror portion and reciprocally rotates the mirror portion around the first rotation axis. The outer actuator 7 is an example of the outer actuator portion of the present invention that is interposed between the outer frame portion and the inner frame portion and reciprocally rotates the inner frame portion around the second rotation axis. The back side space 35 is an example of the displacement space of the present invention that opens on the back side of the optical deflector chip in order to displace the movable part. The recessed part 41 is an example of the recessed part of this invention formed in the position facing the back side of displacement space.

  The outer peripheral side back surface 53, the inner peripheral side back surface 54, and the inner peripheral surface 55 are examples of the back surface portion of the present invention of the support portion. The outer peripheral side back surface 53 is an example of the outer peripheral side back portion of the present invention. The inner peripheral back surface 54 and the inner outer peripheral surface 55 are examples of the inner peripheral back portion of the present invention. The inner outer peripheral surface 55 is an example of an inner peripheral side back portion of the present invention that is bonded to the peripheral wall of the recess in a direction perpendicular to the front and back direction. The inner peripheral surface 55 is an example of the inner peripheral back portion of the present invention that protrudes in the reverse direction from the outer peripheral back portion. The die attach agent 60 is an example of the adhesive of the present invention.

  The annular upright member 93 is an example of an upright portion that stands by being bonded to the bottom of the storage space in the present invention. The end surface of the annular upright member 93 on the side to which the outer peripheral side back surface 53 of the optical deflector chip 1 is applied is an example of the top portion of the upright portion.

  The optical deflector chip 1 of the embodiment is a two-dimensional scanning type optical deflector chip. However, in the present invention, the inner actuator 6 is omitted and only the outer actuator 7 is provided. It can also be applied to chips. In the example of the structure of the one-dimensional scanning type optical deflector chip, the inner frame portion 3 of the optical deflector chip 1 constitutes one rectangular flat mirror portion.

DESCRIPTION OF SYMBOLS 1 ... Optical deflector chip, 2 ... Mirror part (movable part), 3 ... Inner frame part (movable part), 4 ... Outer frame part (support part), 6 ... Inner actuator (Movable part and inner actuator part), 7 ... outer actuator (movable part and outer actuator part), 25 ... optical deflector, 26 ... package, 27 ... storage space, 35 ... back side Space (displacement space), 39, 91 ... bottom, 40 ... seat, 41 ... recess, 42 ... bottom, 43 ... peripheral wall, 53 ... outer periphery side rear surface (outer periphery side rear) Part), 54 ... inner peripheral side back surface (inner peripheral side rear part), 55 ... inner outer peripheral surface (inner peripheral side rear part), 60 ... die attach agent (adhesive), 93 ... An annular standing member (standing portion).

Claims (4)

An optical deflector chip, and a package in which the optical deflector chip is disposed,
The optical deflector chip has a movable part including a light reflecting surface on the front side, and supports the movable part so as to move, and forms a displacement space opened on the inner side in order to displace the movable part. And a support portion to
The package has a recess formed at a position facing the back side of the displacement space, and a seat formed at a position where the back surface of the support portion of the optical deflector chip hits.
The back surface portion of the support portion is an outer peripheral side back portion bonded to the seat portion in the front and back direction, and an inner peripheral back surface bonded to the peripheral wall of the recess in a direction perpendicular to the front and back direction. And an optical deflector. The optical deflector according to claim 1.
The seat portion is formed at the top of the standing portion that is bonded to the bottom portion of the storage space in which the optical deflector chip is stored, and stands.
The optical deflector characterized in that the concave portion is formed on the inner peripheral side of the upright portion. The optical deflector according to claim 1 or 2,
The movable part of the optical deflector chip includes a mirror part having the light reflecting surface on the front side,
An inner frame portion surrounding the mirror portion and disposed inside the outer frame portion as the support portion;
An inner actuator part interposed between the inner frame part and the mirror part to reciprocately rotate the mirror part around a first rotation axis;
It is arrange | positioned in the direction of the 2nd rotation axis orthogonal to the said 1st rotation axis on both sides of the said inner frame, and the inner peripheral side of the said outer frame, Between the said outer frame and the said inner frame An optical deflector comprising: an outer actuator portion interposed and configured to reciprocately rotate the inner frame portion around the second rotation axis. A movable portion including a light reflecting surface on the front side, and a support portion that supports the movable portion so as to move, and forms a displacement space that opens on the back side to displace the movable portion on the inner peripheral side,
The back surface portion of the support portion includes an outer peripheral side back portion that is a plane perpendicular to the front and back direction, and an inner peripheral side back portion that protrudes in the back direction from the outer peripheral side back portion. Optical deflector chip.