JP4514075B2 - Galvano device manufacturing method and galvano device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a galvano device and a galvano device.
[0002]
[Prior art]
The galvano device uses the principle of a galvanometer, and is represented by a galvano mirror device used in a laser beam scanning system or the like. In order to reduce the size of the galvanometer mirror, a method of manufacturing the galvanometer mirror using a semiconductor device manufacturing process has been developed. Japanese Patent Application Laid-Open No. 7-175005 discloses a planar galvanometer mirror and a method for manufacturing the same.
[0003]
FIGS. 1 and 2 are a configuration diagram and a cross-sectional view taken along line AA of the galvanomirror device described in FIGS. 1 and 2 of the publication. The galvanomirror device 1 has a three-layer structure in which upper and lower glass substrates 3 and 4 as upper and lower insulating substrates made of, for example, borosilicate glass are anodically bonded to the upper and lower surfaces of a silicon substrate 2 as a semiconductor substrate, respectively. It has become. And the said upper side glass substrate 3 is laminated | stacked on the right-and-left end of FIG. 1 of the silicon substrate 2 so that the upper part of the movable plate 5 mentioned later may be open | released.
[0004]
The silicon substrate 2 includes a flat movable plate 5 and torsion bars 6 and 6 that pivotally support the movable plate 5 so as to be swingable in the vertical direction with respect to the silicon substrate 2 at the center position of the movable plate 5. It is integrally formed by anisotropic etching. Therefore, the movable plate 5 and the torsion bar 6 are also made of the same material as the silicon substrate 2. A flat coil 7 made of a copper thin film that generates a magnetic field when energized is covered with an insulating film on the upper peripheral edge of the movable plate 5. Further, a total reflection mirror 8 as a reflection mirror is formed by aluminum vapor deposition at the center of the upper surface surrounded by the planar coil 7 of the movable plate 5. Furthermore, a pair of electrode terminals 9 and 9 are provided on the side upper surfaces of the torsion bars 6 and 6 of the silicon substrate 2 so as to be electrically connected via the planar coil 7 and the portions of the torsion bars 6 and 6. The electrode terminals 9, 9 are formed on the silicon substrate 2 simultaneously with the planar coil 7 by electroforming coil method.
[0005]
On the left and right sides of the upper and lower glass substrates 3 in the drawing, a pair of circular permanent members that make a magnetic field act on the planar coil 7 portion on the opposite side of the movable plate 5 parallel to the axial direction of the torsion bars 6, 6. Magnets 10A, 10B and 11A, 11B are provided. As shown in FIG. 2, the three permanent magnets 10A and 10B, which are paired with each other, are provided so that the lower side is the N pole and the upper side is the S pole, and the other three permanent magnets are paired with each other. As shown in FIG. 2, the permanent magnets 11 </ b> A and 11 </ b> B are provided so that the lower side is the S pole and the upper side is the N pole.
[0006]
FIG. 3 is a perspective view for explaining the operation of the movable plate 5 and the torsion bar 6. The displacement angle φ of the movable plate 5 is φ = (Mx / GIp) = (F′L / 8.5 × 10 ⁹ r ⁴ ) × l ₁
It becomes.
Mx: Torsional moment G: Lateral elastic modulus Ip: Polar moment of inertia F ': Spring reaction force of torsion bar L: Distance from center axis of torsion bar to force point l ₁ : Length of torsion bar r: Torsion bar length As can be seen from the previous equation, the displacement angle φ is inversely proportional to the fourth power of the radius r of the torsion bar. That is, it can be seen that the resonance frequency of the movable plate 5 varies greatly depending on the radius of the torsion bar.
[0007]
Next, the manufacturing process of the galvanometer mirror device will be described with reference to FIGS. The top and bottom surfaces of the 300 μm thick silicon substrate 101 are thermally oxidized to form oxide films (1 μm) 102 (step a). Next, a through hole pattern is formed on the back side by photolithography, the oxide film in the through hole portion is removed by etching (step b), and the oxide film in the movable plate forming portion is further removed to a thickness of 0.5 μm ( c process)
[0008]
Next, after providing the wax layer 103 on the surface side, anisotropic etching is performed to 100 μm on the through hole portion (step d). The thin oxide film on the movable plate portion on the back side is removed (step e), and anisotropic etching is performed on the through hole and the movable plate portion by 100 μm (step f). The wax layer 103 on the surface side is removed, and a planar coil and electrode terminal portions (not shown) are formed on the oxide film 102 on the surface side by a conventionally known electroforming coil method, and total reflection is performed by vapor deposition of aluminum. A mirror is formed (step g).
[0009]
Next, after providing the wax layer 103 ′ on the surface side, anisotropic etching is performed on the through hole and the movable plate portion by 100 μm to penetrate the through hole portion, and the wax layer 103 ′ is removed except for the movable plate portion. To do. At this time, the upper and lower oxide films are also removed. Thereby, the movable plate 5 and the torsion bar (not shown) are formed, and the silicon substrate 2 of FIG. 1 is formed (h and i processes).
[0010]
Next, after removing the wax layer from the movable plate portion, the upper glass substrate 3 and the lower glass substrate 4 are bonded to the upper and lower surfaces of the silicon substrate 2 by anodic bonding, respectively (steps j and k). Next, permanent magnets 10A, 10B and 11A, 11B are attached to predetermined positions of the upper and lower glass substrates 3, 4 (l step). Although the above is one manufacturing process, there are various manufacturing methods, and there are various movable plate-integrated galvano device structures.
[0011]
[Problems to be solved by the invention]
The oscillation frequency of the movable plate is determined by many parameters such as the size, weight and shape of the movable plate, the thickness and the length of the torsion bar. In practice, once each dimension is determined, only the variation due to manufacturing variation remains. However, there are many factors that cause fluctuations in the oscillation frequency of the movable plate, such as the production of reflecting mirrors, the manufacture of planar coils, and the processing of movable plates and torsion bars by anisotropic etching, and ensuring a stable frequency in mass production. It is difficult. In addition, since the movable plate oscillates in the atmosphere, the resonance frequency changes due to a change in atmospheric pressure.
[0012]
As a means for adjusting the frequency of the movable plate, it is generally performed by a drive circuit, but the adjustment range of the oscillation resonance frequency of the movable plate by the drive circuit is extremely narrow, and in addition to eliminating the manufacturing variation of the galvano device, the galvano device is manufactured. There was no way to increase yield.
[0013]
[Means for Solving the Problems]
In a method of manufacturing a galvano device in which a movable plate and a torsion bar that pivotably supports the movable plate with respect to the substrate are integrally formed on the substrate, and the torsion is performed while the movable plate is swung. A method of manufacturing a galvano apparatus that adjusts the resonance frequency of the movable plate by processing a bar is provided.
[0014]
The torsion bar is processed based on the difference between the resonance frequency of the movable plate in the use state and the resonance frequency of the movable plate in the resonance frequency adjustment state so that a desired resonance frequency is obtained in the use state. the method of production.
[0015]
A method of manufacturing a galvano apparatus for vapor deposition on a torsion bar in order to adjust the oscillation frequency of the movable plate.
[0016]
A galvano device in which a movable plate and a torsion bar that pivotably supports the movable plate with respect to the substrate are integrally formed on the substrate, and the resonance frequency of the movable plate can be adjusted. A galvano device having a hole for processing a torsion bar for adjusting the resonance frequency of the movable plate by processing the torsion bar. Further, to seal the swinging portion of the movable plate such as an inert in the gas atmosphere or in a vacuum atmosphere at atmospheric pressure.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
7 is a top view of the galvano device, FIG. 8 is a front sectional view of the galvano device, and FIG. 9 is a side sectional view of the galvano device. A mirror 23 is formed at the center of the upper surface of the movable plate 22 formed integrally with the silicon substrate 21, and a planar coil 24 is formed at the periphery. The movable plate 22 is formed in a hollow state on the silicon substrate 21 and is held by torsion bars 25 and 26 formed integrally with the silicon substrate 21. The silicon substrate 21 is fixed to the upper surface of a base 28 fixed to the upper surface of the base substrate 27. Permanent magnets 29 and 30 are arranged above and below the silicon substrate 21, and a yoke 31 is placed on the periphery of the base substrate 27.
[0018]
When the planar coil 24 formed on the movable plate 22 is energized, the movable plate 22 rotates around the torsion bars 25 and 26 as rotation centers. A large number of such galvanometer mirrors are formed on the silicon substrate 21, and are used separately after completion. A pattern 27 a is formed on the base substrate 27, and the pattern 27 a and the pattern 21 a formed on the silicon substrate 21 are connected by a wire 33. The pattern 27a is provided with a through hole 27b and is connected to the outside through the through hole 27b. The through hole 27 b is connected to the side through hole 27 c through a wiring pattern (not shown) provided on the lower surface of the base substrate 27.
[0019]
In order to solve the problems of the prior art, in the present invention, the resonance frequency is adjusted by processing the torsion bar while swinging the movable plate. For the adjustment, a method of adjusting the galvano mirror unit alone or a method of final adjustment after the galvano device is completed can be adopted.
[0020]
FIG. 10 is a schematic diagram for explaining the resonance frequency adjustment of the movable plate of the present invention. (A) A sectional view in which a galvano mirror is set on a pedestal, (B) is a sectional view in which a pedestal in which a galvano mirror is set on a frequency adjusting jig is placed, and (C) is a sectional view during frequency adjustment. First, the galvanometer mirror is set on the base 40. Next, the pedestal is placed on a frequency adjusting jig. The frequency adjusting jig is obtained by replacing the base substrate 27 of the galvano apparatus with a base 41. The base 41 is provided with through holes 41a and 41b for processing the torsion bars 25 and 26. The through holes 41a and 41b are provided so as to face the lower surface portions of the torsion bars 25 and 26, and vapor deposition or ion beam irradiation can be performed on the torsion bars 25 and 26 from below the through holes 41a and 41b. Set the frequency adjustment jig on the vapor deposition machine or ion etching machine.
[0021]
The probe 42 is brought into contact with the pattern 21 a formed on the silicon substrate 21 to swing the movable plate 22. The galvanometer mirror having a low resonance frequency of the movable plate 22 can raise the resonance frequency by vapor deposition on the torsion bars 25 and 26. On the contrary, the resonance frequency of the galvano mirror having a high resonance frequency of the movable plate 22 can be lowered by thinning the torsion bars 25 and 26 by ion etching. For example, the movable plate 22 is swung and aluminum is vapor-deposited from the vapor deposition nozzle 43 while measuring the resonance frequency. When the desired frequency is reached, vapor deposition is interrupted by the shutter 44 and the frequency adjustment is terminated. It should be noted here that partial deposition is not performed in the longitudinal direction of the torsion bars 25 and 26, or partial ion etching is not performed and partial thinning is not performed. When it is partially deposited on the torsion bars 25 and 26 or partially ion-etched and partially thinned, stress concentration occurs at the time of rocking, and the frequency adjustment tends to vary and is stable. This is because the oscillation cannot be continued. In mass production, instead of selectively performing vapor deposition and ion etching, select an adjustment method, create a galvanomirror to have a frequency according to the adjustment method, and finally adjust the frequency It goes without saying that is adopted.
[0022]
Since the galvanometer mirror swings the movable plate, it is subject to air resistance when used in the atmosphere. Since the resonance frequency differs between the atmosphere used for frequency adjustment and atmospheric pressure, the difference between the atmospheric pressure and the resonance frequency at the time of frequency adjustment must be obtained in advance, and the resonance frequency when returning to the atmosphere must be calculated and adjusted. There is.
[0023]
The above is the description of the method of adjusting the frequency with a single galvanometer mirror. Next, a method of adjusting the resonance frequency after the galvano device is completed will be described. FIG. 11 is a cross-sectional view after the galvano device is completed, and FIG. 12 is a cross-sectional view in which the galvano device is set on a resonance frequency adjusting jig. FIG. 13 is a perspective view of a resonance frequency adjusting jig. The galvano device is different from the prior art in that a through hole 45 a for setting the resonance frequency adjusting jig 46 is formed in the base substrate 45. The resonant frequency adjusting jig 46 includes a convex portion 47, and through-holes 47a and 47b are formed in the convex portion 47 so that the upper portion faces the lower surface of the torsion bar and the lower portion is seen by the frequency adjusting means. The resonance frequency is adjusted while driving the galvanometer mirror from a pattern (not shown) formed on the base substrate 45 and swinging it.
[0024]
FIG. 14 is a block diagram of an apparatus for adjusting the resonance frequency. The galvano device 51 is driven by an oscillator 50. The galvanometer mirror is irradiated with the laser 52 and the reflected laser light is detected by the light receiving element 53. The frequency of the galvanometer mirror is measured by counting the detected signal by the frequency counter 54 and output to the comparator 55. The frequency signal from the standard oscillation circuit 56 and the signal from the memory 57 are input to the comparator 55. The memory 57 stores the difference between the resonance frequency when the galvano is used and the resonance frequency in the resonance frequency adjusting device. The comparator 55 calculates data from the frequency counter 54, the standard oscillation circuit 56, and the memory 57, and controls the frequency adjustment unit 58. When the output of the frequency counter 54 matches the desired frequency, the frequency adjustment is terminated. The frequency adjusting means may be vapor deposition, ion etching, laser beam, etc., but means capable of processing the torsion bar evenly is desirable.
[0025]
In the galvano device, the oscillating part is exposed to the atmosphere in a completed state, but since the oscillating part oscillates, in order to obtain a stable resonance frequency without being influenced by fluctuations in atmospheric pressure, Vacuum sealing or sealing at atmospheric pressure is preferable. Although fewer driving current of the movable portion so when vacuum sealing air resistance is eliminated, the structure for vacuum sealing becomes complicated, it is necessary to apparatus for vacuum sealing. In air sealing, there is no problem that causes a problem in vacuum sealing, but the vapor deposition material used for torsion bar processing may be oxidized, which may cause a change in resonance frequency over time. In the present invention, in the case of atmospheric pressure sealing , the sealing atmosphere of the movable part is an inert gas. For example, pure nitrogen gas is used for sealing.
[0026]
【The invention's effect】
Since the resonance frequency is adjusted by processing the torsion bar while swinging the movable plate, the resonance frequency can be adjusted to a desired resonance frequency, and the problem of the resonance frequency of the galvano device can be eliminated.
[0027]
The resonance frequency of the use state, since the frequency adjustment method in consideration of the difference in the resonance frequency during adjustment, can be adjusted to a desired frequency in use.
[0028]
It is possible to reinforce the torsion bar by adjusting the frequency by vapor deposition on the torsion bar.
[0029]
By enabling the resonance frequency to be adjusted after the galvano device is completed, it is possible to eliminate the frequency variation factor after the frequency adjustment.
[0030]
When sealing a movable part in an inert gas atmosphere under atmospheric pressure, it is possible to eliminate the pressure change after sealing, also by preventing oxidation of the galvanometer mirror can be reduced the time course of the resonance frequency. Furthermore, the change of the reflectance of a galvanometer mirror can also be suppressed. Further, when the movable part is sealed in a vacuum atmosphere, the resistance of air is eliminated, so that the drive current of the movable part can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a galvanomirror device. FIG. 2 is a cross-sectional view taken along the line AA. FIG. 3 is a perspective view for explaining operations of a movable plate 5 and a torsion bar. Process [FIG. 5] Manufacturing process of galvano mirror device [FIG. 6] Manufacturing process of galvano mirror device [FIG. 7] Top view of galvano device [FIG. 8] Front sectional view of galvano device [FIG. 9] Side sectional view of galvano device 10 is a schematic diagram for explaining the resonance frequency adjustment of the movable plate of the present invention. FIG. 11 is a cross-sectional view after the galvano device is completed. FIG. 12 is a cross-sectional view in which the galvano device is set on the resonance frequency adjusting jig. FIG. 13 is a perspective view of a resonance frequency adjusting jig. FIG. 14 is a block diagram of an apparatus for adjusting the resonance frequency.
DESCRIPTION OF SYMBOLS 1 Galvano mirror apparatus 2 Silicon substrate 3 Upper glass substrate 4 Lower glass substrate 5 Movable plate 6 Torsion bar 7 Flat coil 8 Total reflection mirror 9 Electrode terminal 10A Permanent magnet 10B Permanent magnet 11A Permanent magnet 11B Permanent magnet 101 Silicon substrate 102 Oxide film 103 Wax layer 103 'Wax layer 21 Silicon substrate 21a Pattern 22 Movable plate 23 Mirror 24 Planar coil 25 Torsion bar 26 Torsion bar 27a Pattern 27b Through hole 27c Side through hole 28 Base 29 Permanent magnet 30 Permanent magnet 31 York 33 Wire 40 Base 41 Base 41a Through-hole 41b Through-hole 42 Probe 43 Deposition nozzle 44 Shutter 45 Base substrate 45a Through-hole 46 Resonance frequency adjusting jig 47 Projection 47a Through-hole 47b Through-hole 50 Oscillator 51 Ga Bas Bruno device 52 laser 53 light-receiving element 54 frequency counter 55 comparator 56 standard oscillator circuit 57 memory 58 frequency adjusting means

Claims (5)

  In a method of manufacturing a galvano device in which a movable plate and a movable plate that pivotably supports the movable plate with respect to the substrate are integrally formed on the substrate, and the movable plate is swung, the torsion is performed while the movable plate is swung. A method of manufacturing a galvano device, comprising adjusting a resonance frequency of a movable plate by processing a bar. The torsion bar is processed based on the difference between the resonance frequency of the movable plate in the usage state and the resonance frequency of the movable plate in the resonance frequency adjustment state so that a desired resonance frequency is obtained in the usage state. The manufacturing method of the galvano apparatus of Claim 1 characterized by these. Manufacturing method of a galvano apparatus according to claim 1 or 2, characterized in that to adjust the resonance frequency of the movable plate by depositing on the torsion bar. A galvano device in which a movable plate and a torsion bar that pivotably supports the movable plate relative to the substrate are integrally formed on the substrate, and the resonance frequency of the movable plate can be adjusted,
A galvano device having holes for processing a torsion bar for adjusting the resonance frequency of the movable plate by processing the torsion bar while swinging the movable plate . The galvano device according to claim 4 , wherein at least the movable part is sealed in an inert gas atmosphere or a vacuum atmosphere at atmospheric pressure.

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