JP4969136B2 - Actuator manufacturing method - Google Patents

Description

The present invention has an outer frame portion in a semiconductor substrate, relates to a manufacturing method of actuator integrally forming the beam portion and the movable portion, in particular, can greatly swung movable portion even DC (non-resonant), also for optical scanning actuator method for producing the actuator is no restriction of the light beam scanning range when applied to.

  Conventionally, as a manufacturing method of a planar type actuator in which an outer frame portion, a beam portion, and a movable portion are integrally formed on a semiconductor substrate, it is formed to a predetermined thickness (for example, about 100 μm) in consideration of driveability of the movable portion by polishing or the like. After oxidizing the surface of the silicon substrate and forming a drive coil (in the case of an electromagnetically driven actuator) as an electrical wiring part to which an electrical signal for driving the movable part is supplied from the drive circuit, in the movable part forming part of the semiconductor substrate, There is a method in which a semiconductor substrate is anisotropically etched to form a through hole, and an outer frame portion, a beam portion, and a movable portion are formed (see, for example, Patent Document 1).

Further, the surface of the silicon substrate formed to have a predetermined thickness (for example, about 100 μm) considering the driveability of the movable part by polishing or the like is oxidized, and a supporting member such as a glass substrate is bonded to one surface of the semiconductor substrate or the anode After joining and forming a drive coil in the movable part forming part opposite to the support member mounting surface of the semiconductor substrate, the silicon substrate is anisotropically etched to form a through hole, an outer frame part, a beam part and a movable part There is a method of forming (see, for example, Patent Document 2).
JP 2002-14297 A JP-A-2005-88152

  However, in the former manufacturing method, since a semiconductor substrate to be handled is thin, a general-purpose manufacturing apparatus cannot be used in a drive coil formation process or the like, and a new special manufacturing apparatus is required. In addition, since the semiconductor substrate is thin, it is difficult to handle during and after the manufacturing process.

  On the other hand, in the latter manufacturing method, a general-purpose manufacturing apparatus can be used by joining and thickening the support member to the semiconductor substrate before the drive coil forming step. However, since the semiconductor substrate itself is thin, the support member It is difficult to handle the semiconductor substrate when it is bonded. In addition, when applied to an optical scanning actuator, a reflective mirror is provided on the movable part. However, when a reflective mirror is formed on the support member joining side on the side opposite to the coil forming surface of the movable part, the thickness of the support member causes the light beam to be reflected. There is a problem that the angle of incidence and reflection is restricted and the light beam scanning range becomes narrow. On the other hand, when the reflecting mirror is formed on the coil forming surface side, there is no restriction on the light beam scanning range, but the reflecting mirror is formed at the center of the movable portion avoiding the drive coil forming portion, so the supporting member mounting surface of the semiconductor substrate Compared with the case where it forms in the side, a reflective mirror will become small. If an attempt is made to secure the same reflecting mirror size as that formed on the support member mounting surface side of the semiconductor substrate, the outer shape of the chip becomes large.

  By the way, this type of planar type actuator can drive the movable part with a smaller force as the movable part thickness is thinner, and the driveability of the movable part is improved. In view of handling properties after completion, it is difficult to form the movable part extremely thin (for example, about 50 μm or less).

If an SOI (Silicon On Insulator) substrate is used, handling properties in the manufacturing process can be ensured, and the intermediate SiO ₂ layer becomes an etch stop layer, so that the thickness of the movable part can be precisely controlled and the movable part is made extremely However, since the SOI substrate is expensive, there is a problem that the manufacturing cost of the actuator is increased.

The present invention has been made paying attention to the above-mentioned problems, manufacturing cost is low, can improve the driveability of the movable part, and when applied to an optical scanning actuator, an actuator whose light beam scanning range is not restricted , An object of the present invention is to provide an actuator manufacturing method that can be manufactured at low cost without using an SOI substrate.

For this reason, the actuator manufacturing method according to the first aspect of the present invention is pivotally supported by the outer frame portion through the outer frame portion, the beam portion, and the beam portion integrally formed with the semiconductor substrate. An actuator manufacturing method comprising an actuator unit having a movable part and an electric wiring part to which an electrical signal for driving the movable part is supplied, and a semiconductor substrate having a thickness that does not hinder handling during the manufacturing process is prepared. The step of forming the electric wiring portion on the actuator portion forming portion on one surface of the semiconductor substrate and the support for supporting the actuator portion on the same surface as the electric wiring portion forming side of the semiconductor substrate after the electric wiring portion is formed and bonding a supporting member for parts forming the supporting member and the supporting member joining surface opposite to the semiconductor substrate surface after bonding, a desired thickness required for the actuator unit A step of grinding in the actuator portion formation region of a semiconductor substrate after grinding, characterized in that it comprises a step of forming a beam portion and the movable portion by etching.

According to a second aspect of the present invention, in the electric wiring portion forming step, a driving coil that generates a magnetic field by energization is preferably formed on the movable portion.
According to a third aspect of the present invention, a step of forming a reflection mirror on a surface of the movable portion opposite to the electric wiring portion forming surface may be provided after the beam portion and movable portion forming step.

According to the manufacturing method of the present invention, a semiconductor substrate having a thickness that does not hinder handling during the manufacturing process is prepared, and an electric wiring portion is formed at an actuator portion forming portion on one surface of the semiconductor substrate. After bonding the support member to the surface side, the semiconductor substrate is ground to an arbitrary thickness, so that a thicker semiconductor substrate can be used compared to the conventional one, and in the manufacturing process including the electric wiring part forming process The handling property is improved, and a general-purpose manufacturing apparatus can be used. Further, since the thickness of the semiconductor substrate can be freely adjusted with the support member joined, there is an advantage that it is possible to cope with high-mix low-volume production if stored and managed with the support member joined. Furthermore, by grinding the part corresponding to the movable part of the actuator part with good handling by the support member, an actuator with a very thin movable part can be formed, and the movable part can be rotated (large) even with direct current (non-resonant). An actuator having excellent drivability that can be (amplitude driven) can be manufactured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an exploded perspective view showing a configuration example of an actuator manufactured by the actuator manufacturing method according to the present invention. In the following description, a one-dimensional galvanometer mirror, which is an electromagnetically driven optical scanning actuator, will be described as an example.
The galvanometer mirror shown in FIG. 1 includes an actuator unit 1 and a support unit 10.

  The actuator part 1 has a configuration in which a movable part 4 is pivotally supported by an outer frame part 2 by a pair of beam parts 3 and 3. The outer frame portion 2, the beam portions 3 and 3, and the movable portion 4 all have the same thickness, and are integrally formed with a semiconductor substrate such as a silicon substrate 20 (shown in FIG. 4) as will be described later. .

  A drive coil 5 that is an electric wiring portion to which a drive current is supplied as an electric signal for driving the movable portion from a drive circuit (not shown) is formed on the peripheral portion on the surface side of the movable portion 4. The drive coil 5 is pulled out to the outer frame portion 2 side through the beam portions 3 and 3 and connected to the pair of electrode terminals 6 and 6, and the electrode terminals 6 and 6 are connected to the drive circuit by, for example, wire bonding. . For example, a pair of permanent magnets 7 and 7 that generate a static magnetic field are disposed outside the outer frame portion 2 on the opposite side of the movable portion 4 parallel to the axis of the beam portions 3 and 3. A reflection mirror 8 (shown in FIG. 3F) formed of, for example, aluminum is formed on the entire back surface of the movable portion 4.

  Further, a support portion 10 that supports the actuator portion 1 is joined to the surface of the outer frame portion 2 (upper surface in FIG. 1) on the same side as the drive coil 5 formation surface of the actuator portion 1 by an adhesive or anodic bonding. The support portion 10 is formed of, for example, a glass substrate, and has a sufficient depth at a portion corresponding to the movable portion 4 and the beam portions 3 and 3 of the actuator portion 1 so as not to hinder the rotation operation of the movable portion 4. A concave groove 11 is formed on the top. Further, through holes 12 and 12 are formed in portions corresponding to the electrode terminals 6 and 6 of the outer frame portion 2, and the electrode terminals 6 and 6 and the drive circuit are connected by wire bonding through the through holes 12 and 12. It is supposed to be. A through hole may be used instead of the groove 11.

The operation of this electromagnetically driven galvanometer mirror will be briefly described.
When a drive current is supplied from the drive circuit to the drive coil 5 on the movable part 4, a magnetic field is generated. A Lorentz force is generated by the interaction between this magnetic field and the static magnetic field generated by the permanent magnets 7, 7. Electromagnetic forces in opposite directions are generated on opposite sides of the movable part parallel to the axial direction, and the movable part 4 rotates about the beam parts 3 and 3 as the axis center. With this rotation, the beam portions 3 and 3 are twisted and a spring force is generated in the beam portions 3 and 3. The movable portion 4 rotates to a position where the spring force of the beam portions 3 and 3 and the electromagnetic force generated by supplying the drive current are balanced.

  If a direct current is applied to the drive coil 5 as a drive current, the movable part 4 stops at a rotation position corresponding to the amount of current. Therefore, the rotation angle of the movable part 4 is controlled in accordance with the amount of current to control the desired light beam. An optical deflector capable of deflecting in the direction can be realized. If an alternating current such as a sine wave is passed through the drive coil 5 as a drive current, the movable part 4 swings, so that the light beam can be scanned by the reflection mirror 8. If the frequency of the alternating current is set to the resonance frequency of the oscillating motion of the movable portion 4, an optical scanning device capable of continuous scanning at a constant period can be realized.

  According to the actuator having such a configuration, since the support portion 10 is on the drive coil forming surface side, a light beam is incident on the support portion 10 by forming the reflection mirror 8 on the side opposite to the drive coil forming surface of the movable portion 4. In addition, the light beam scanning range can be widened without worrying that the angle of reflection is restricted. Further, since the reflecting mirror 8 can be formed on the entire surface of the movable portion 4, the mirror size can be increased. Further, if the reflection mirror having the same size as the case where the reflection mirror is formed in the central portion of the movable portion while avoiding the drive coil portion as in the prior art, the chip outline of the entire actuator portion 1 can be reduced in size.

  Next, an actuator manufacturing method according to the present invention will be described with reference to FIGS. 2 to 4 by taking the galvanomirror manufacturing method of FIG. 1 as an example. 2 and 3 show a cross section taken along line AA in FIG.

In the step (a) of FIG. 2, a silicon substrate 20 having a sufficient thickness (for example, 250 μm or more) is prepared so that a general-purpose manufacturing apparatus can be used in the drive coil forming step and the like, and handling is not hindered during the manufacturing step. and, the upper and lower surfaces of the silicon substrate 20 after the formation of the SiO ₂ insulating layer 21 of about 1μm is thermally oxidized, SiO ₂ insulating layer of the driving coil forming surface opposite the silicon substrate surface side (lower side in the figure) only Are removed by wet etching or dry etching. The insulating layer is not limited to thermal oxidation, and may be formed only on the drive coil forming surface side of the silicon substrate 20 by a known method such as CVD. Further, the SiO ₂ insulating layer on the silicon substrate surface opposite to the drive coil forming surface (lower side in the figure) is not removed in this step, but is removed at the time of grinding in step (d) of FIG. 3 to be described later. Anyway.

Next, in step (b), the drive coil 5 is formed on the SiO ₂ insulating layer 21 of the silicon substrate 20. The drive coil 5 is formed by forming a thin film of aluminum as a highly conductive metal, for example, with a thickness of about 1 μm on the entire surface of the SiO ₂ insulating layer 21 by a known film formation technique such as sputtering. Thereafter, a resist is applied thereon, and a resist pattern having an electric wiring shape is formed while leaving a resist for the electric wiring portion including the drive coil 5, the lead line, and the electrode terminals 6 and 6. Then, using this as a mask, the aluminum thin film is etched to form the drive coil 5, lead lines and electrode terminals 6 and 6. Etching may be performed by either wet etching using an etching solution or dry etching using a reactive gas. Next, an insulating layer of photosensitive polyimide is formed on the electric wiring portion. In this case, the insulating layer is patterned except for portions corresponding to electrode terminals 6 and 6 (see FIG. 1) for electrical connection with an external drive circuit. Specifically, photosensitive polyimide is applied and formed on the entire upper surface of the silicon substrate 20 side. The coating is performed by applying a known method such as a spin coating method, a slit die coating method, a spray method, a roll coating method, or a dip method. Here, for example, when positive type photosensitive polyimide is used, a necessary portion other than the portions corresponding to the electrode terminals 6 and 6 is masked and exposed to ultraviolet rays. In the case of the positive type photosensitive polyimide, the exposed portion is dissolved in the developer, so that the portion corresponding to the electrode terminals 6 and 6 is exposed and developed to remove the corresponding portion of the photosensitive polyimide. The insulating layer on the electric wiring portion is not limited to polyimide, but may be a SiO ₂ film, a SiN film, or the like that can be formed by a known method such as CVD.

  Next, in the step (c), the support member 30 for forming the support portion 10 is bonded to the same surface as the formation surface of the drive coil 5 of the silicon substrate 20. As shown in FIG. 4, the support member 30 is a glass substrate having the same shape as the silicon substrate 20 and having a thickness of, for example, about 350 μm, and the movable portion 4 and the beam portions 3 and 3 of each actuator portion forming portion of the silicon substrate 20. A plurality of groove portions 31 are formed corresponding to the corresponding portions. These groove portions 31 can be formed by dry etching or the like. As shown in FIG. 4, the silicon substrate 20 and the support member 30 are laminated by aligning the positions of the orientation flats 20a and 30a of the silicon substrate 20 and the support member 30 and bonding them by anodic bonding or an adhesive. The alignment between the silicon substrate 20 and the support member 30 may be performed by providing dedicated alignment marks. 2 and 3 show a process of forming one actuator part in the silicon substrate 20. FIG.

  Next, in the step (d) of FIG. 3, the silicon substrate 20 surface side opposite to the bonding surface of the support member 30 is ground, and the silicon substrate 20 is removed from the outer frame portion 2 of the actuator portion 1, the beam portions 3, 3 and The desired thickness required for the movable part 4 is set.

  Next, in step (e), the silicon substrate 20 is etched to form the actuator unit 1. The portions corresponding to the outer frame portion 2, the beam portions 3, 3 and the movable portion 4 in FIG. 1 on the lower surface of the silicon substrate 20 are covered with a resist mask, and the silicon substrate is vertically penetrated by anisotropic etching. As a result, the actuator portion 1 shown in FIG. 1 is formed on the silicon substrate 20 in a state where the movable portion 4 is pivotally supported on the outer frame portion 2 by the pair of beam portions 3 and 3.

  Next, in step (f), a reflecting mirror 8 such as aluminum is formed on the back surface side of the movable portion 4 of the actuator portion 1 formed on the silicon substrate 20 (the lower surface side in FIG. 3F) by vapor deposition or the like. Thereafter, each actuator portion 1 portion of the silicon substrate 20 is cut and separated from each other to form a galvanometer mirror chip. This chip is mounted on a substrate, and a pair of permanent magnets 7 and 7 are attached to the outer side of the outer frame portion 2 on the opposite side of the movable portion 4 parallel to the axis of the beam portions 3 and 3. As shown in FIG. 1, the galvanometer mirror shown in FIG. 1 is completed by facing each other. In addition, when mounting the said chip | tip on a board | substrate, when the reflective mirror 8 is located in a board | substrate side, it cannot be overemphasized that an opening part is formed in the board | substrate part corresponding to the reflective mirror 8. FIG.

  According to such an actuator manufacturing method, after the support member 30 is bonded to the drive coil forming surface side, the silicon substrate 20 can be ground to an arbitrary thickness, so that it is thicker than the conventional one (for example, about 250 μm). As described above, the silicon substrate 20 can be used, the handling property in the manufacturing process including the coil forming process is good, and a general-purpose manufacturing apparatus can be used. Further, since the thickness of the silicon substrate 20 can be freely adjusted with the support member 30 joined, there is an advantage that if the storage management is carried out with the support member 30 joined, it is possible to cope with high-mix low-volume production. Furthermore, the movable part 4 of the actuator part 1 can be ground by the support member 30 in a state where the handling is good, whereby an actuator having a very thin movable part 4 (for example, about 10 μm or less) can be formed. Therefore, the movable part 4 can be driven with a small torque, and an actuator excellent in drivability that can rotate the movable part 4 greatly (large amplitude drive) even with direct current (non-resonant) can be manufactured.

The actuator Manufacturing method of the present invention is not limited to the electromagnetically driven above, can be applied electrostatically actuated, the piezoelectric driving type or the like.

The perspective view which shows the structural example of the actuator manufactured with the actuator manufacturing method which concerns on this invention Explanatory drawing which shows the manufacturing process at the time of applying the actuator manufacturing method based on this invention to the actuator of FIG. Explanatory drawing which shows the manufacturing process following FIG. The perspective view for demonstrating the joining process of a semiconductor substrate and a supporting member

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Actuator part 2 Outer frame part 3, 3 Beam part 4 Movable part 5 Drive coil 8 Reflection mirror 10 Support part 20 Silicon substrate 30 Support member

Claims (3)

Electricity which has an outer frame part integrally formed with a semiconductor substrate, a beam part, and a movable part pivotally supported on the outer frame part via the beam part, and is supplied with an electric signal for driving the movable part An actuator manufacturing method comprising an actuator unit having a wiring unit,
Preparing a semiconductor substrate having a thickness that does not hinder handling during the manufacturing process, and forming the electrical wiring portion on the actuator portion forming portion on one surface of the semiconductor substrate; and
Bonding a support member for forming a support part for supporting the actuator part to the same surface as the electrical wiring part forming side of the semiconductor substrate after the electrical wiring part is formed;
Grinding the semiconductor substrate surface opposite to the support member bonding surface after the support member bonding to a desired thickness required for the actuator unit;
Forming a beam portion and a movable portion by etching in the actuator portion forming portion of the semiconductor substrate after grinding;
An actuator manufacturing method comprising:   2. The actuator manufacturing method according to claim 1, wherein in the electric wiring portion forming step, a drive coil that generates a magnetic field by energization is formed on the movable portion.   3. The actuator manufacturing according to claim 1, wherein a step of forming a reflection mirror on a surface of the movable portion opposite to the electric wiring portion forming surface is provided after the beam portion and the movable portion forming step. Method.

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