JP4014273B2 - Manufacturing method of optical scanner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an optical scanner, and more particularly to a method for manufacturing a small optical scanner that reflects light from a light source and scans the reflected light in one or two dimensions.
[0002]
[Prior art]
Japanese Patent Application Laid-Open No. 7-175005 discloses an optical scanner intended for deflection scanning of laser light and a method for manufacturing the same. FIG. 8 shows the configuration of the optical scanner disclosed in this publication. A movable mirror 201 connected by a support 200 and a torsion spring 202, a drive coil 204 formed on the movable mirror 201, and a magnetic pole 205 are shown. And a permanent magnet 206 having the same. When an alternating current is passed through the drive coil 204 via the electrode pad 203, the movable mirror 201 is oscillated by the interaction with the magnetic field generated by the permanent magnet 206, and the reflected light from the movable mirror 201 is deflected and scanned. .
[0003]
Further, as a configuration suitable for miniaturization of the optical scanner shown in FIG. 8, an application of a method for manufacturing a semiconductor integrated circuit has been proposed in Japanese Patent Application No. 8-279340.
[0004]
9 to 12 are diagrams showing manufacturing steps when the above-described optical scanner is manufactured by applying a manufacturing method of a semiconductor integrated circuit. First, as shown in FIG. 9, a silicon nitride film 302 and a drive coil 303 are sequentially formed on the surface of a silicon substrate 301. Next, as shown in FIG. 10, after the polyimide film 304 is formed by patterning, wirings 306 are formed through the contact holes 305. FIG. 11 shows the portion indicated by the arrow in FIG. 10 (this portion becomes a torsion spring) viewed from the direction along the rotation axis of the movable mirror. FIG. 12 described next is also a cross-sectional view seen from this direction.
[0005]
Next, as shown in FIG. 12, after forming a torsion spring 308 by patterning a polyimide film 307, a part of the silicon substrate 301 is removed by etching, whereby a support 309 and a movable mirror (in FIG. (Not shown) are formed separately. In this conventional example, since the polyimide film 307 includes wiring and the like, it is necessary to form and pattern the polyimide film 307 multiple times. However, the drive coil 303 and the wiring 306 are protected by the polyimide film 307. There are advantages such as excellent temporal change and environmental resistance.
[0006]
[Problems to be solved by the invention]
In FIG. 12, when the second layer polyimide film 307 is formed, the base is not flat, and there is a step (usually about 5 to 30 μm) due to the first layer of polyimide 304, so a polyimide precursor is spin coated on the surface. When applied by the method, very severe film thickness unevenness occurs. Further, when an alignment shift occurs between the pattern of the first layer of polyimide 304 and the pattern of the second layer of polyimide 307, a step is formed on the side surface of the torsion spring 308. For this reason, the resonant frequency of the optical scanner may not be stabilized due to variations in the thickness direction of the torsion spring 308 and the side shape of the torsion spring 308, and cracks may occur from the stepped portion formed on the side surface of the torsion spring 308. This causes a problem that the life of the torsion spring 308 is reduced.
[0007]
Furthermore, in the figure, strong alkali chemicals such as TMAH and KOH are used for etching the silicon substrate 301. These chemicals are important for organic polymers such as polyimide and optical electrode materials such as aluminum that constitute an optical scanner. These parts must be protected in some way during etching because they erode violently.
[0008]
As a typical protection method, as shown in FIG. 13, before the immersion in the etching solution 313, a stainless cap 311 or the like is formed on the silicon substrate 310 through an O-ring 312 made of silicon resin. There are a method of mounting on the surface and a method of covering with a protective film 314 such as a silicon nitride film or a fluororesin as shown in FIG.
[0009]
However, these conventional methods have the following problems. First, in the case of the method shown in FIG. 13, since a pressure difference due to water pressure is generated between the front surface and the back surface of the silicon substrate 310, when a part of the optical scanner element is exposed immediately before the etching of silicon is completed, a part of the element constituent film is formed. Cracks occur, and the problem arises that the etching solution 313 enters the surface protected by the cap 311 through the cracks.
[0010]
In the method shown in FIG. 14, particularly when a fluororesin is used for the protective film 314, a resist asher is used when removing the protective film 314 after the etching of silicon. However, when an organic insulating film such as polyimide is used as the material of the torsion spring, there is a problem that the torsion spring is damaged during the removal process.
[0011]
The manufacturing method of the optical scanner of the present invention has been made paying attention to such a problem, and the object is to achieve uniform element characteristics by reducing variation in the dimensions of the elastic member, An object of the present invention is to provide a method of manufacturing an optical scanner that can improve the lifetime of an element by smoothing the side surface of an elastic member.
[0012]
Another object of the present invention is to provide an optical scanner manufacturing method capable of improving the manufacturing yield of an optical scanner by preventing deterioration of elements in an etching process and a protective film removing process that is a subsequent process. It is to provide.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing an optical scanner according to a first aspect of the present invention includes a support, a movable plate having a reflecting surface for reflecting light on at least one surface, and the movable plate. And an elastic member that connects between the support and the support plate, and a drive coil formed on the surface of the movable plate, and an elastic force generated in the elastic member by generating a force between the support and the movable plate. In an optical scanner manufacturing method in which the movable plate is deflected by deformation, a step of forming an etching mask for etching the substrate on one surface of the substrate, and forming a plurality of elastic films on the other surface of the substrate a step of, forming an etching mask for etching the elastic film of plural layers forming region of the movable plate and the elastic member on the surface of the elastic membrane, the elastic membrane etch Forming a protective film on the other surface of the substrate including the Gumasuku, separating form the said support and the movable plate by the substrate etch mask not covered with portions of the substrate is etched and removed And removing the protective film; and forming the elastic member by removing a portion of the plurality of layers of the elastic film that is not covered with the elastic film etching mask in one process; Removing the elastic film etching mask and the substrate etching mask .
[0014]
According to a second aspect of the present invention, there is provided a method for manufacturing an optical scanner according to the first aspect of the present invention, wherein the elastic film includes an electrical element.
According to a third aspect of the present invention, there is provided an optical scanner manufacturing method according to the first aspect, wherein the elastic film etching mask is formed of a silicon oxide film, and the protective film is a silicon nitride film. It is composed of
[0015]
According to a fourth aspect of the present invention, there is provided an optical scanner manufacturing method according to the first aspect, wherein the elastic film etching mask is formed of a silicon oxide film or a silicon nitride film, and the protective film is formed. Is made of fluororesin.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiment of the present invention will be described in detail along the optical scanner manufacturing process. First, as shown in FIG. 1, after a silicon nitride film 102 is formed on the surface of a silicon substrate 101 by a method such as LP-CVD (Low Pressure-Chemical Vapor Deposition), etching of a silicon substrate 101 to be described later of the silicon substrate 101 is performed. A part of the silicon nitride film 102 is etched and removed only on one surface of the silicon substrate 101 (the lower surface of the silicon substrate 101 in the figure) using a photoresist or the like as a mask so that the portion removed in the process is exposed. Further, an aluminum film is formed on the surface from which the silicon nitride film 102 has not been removed (upper surface of the silicon substrate 101 in the figure) by a technique such as sputtering, vacuum evaporation, plating, etc., and then etched using a photoresist or the like as a mask. A drive coil 103 as an electric element is formed.
[0017]
Next, as shown in FIG. 2, after a polyimide precursor is formed on the silicon substrate 101 including the drive coil 103 by spin coating, a contact hole 105 is formed at the junction between the drive coil 103 and the wiring 106. . Here, as a method for forming the contact hole 105, there are a method of forming by photo-etching using photosensitive polyimide, a method of removing the portion of the contact hole 105 with a developer using a photoresist as a mask, etc. In the example, the torsion spring portion is patterned at this point, but in this embodiment, the torsion spring portion is not patterned at this point. Further, after the polyimide precursor 104 is heated to form the polyimide film 104 as an elastic film, the wiring 106 as an electric element is formed in the same manner as the drive coil 103.
[0018]
Next, as shown in FIG. 3, a polyimide precursor is formed on the surface of the silicon substrate 101 including the wiring 106 (including the surface of the polyimide film 104) by spin coating, and then heated to form an elastic film. A polyimide film 107 is formed. Here, in the present embodiment, since the torsion spring is not patterned when the first polyimide film 104 is formed, there is no step on the base other than the periphery of the contact hole 105 in this step. Therefore, uniform film formation is possible even in the second-layer polyimide film 107.
[0019]
Next, after a silicon oxide film is formed on the surface of the polyimide film 107 by a method such as P-CVD (Plasma Assisted Chemical Vapor Deposition), the portion indicated by 109 in FIG. 4 is removed as a mask opening using a photoresist or the like as a mask. Thus, an etching mask 108 is formed. Here, FIG. 4 is a view of FIG. 3 as viewed from above (the surface on which the drive coil 103 is formed).
[0020]
Next, as shown in FIG. 5, after a silicon nitride film 110 is formed on the surface of the silicon substrate 101 including the etching mask 108 by a method such as P-CVD, the silicon nitride films 102 and 110 of the silicon substrate 101 are covered. The movable mirror (movable plate) 111 and the support 112 are separated from each other by etching away the unexposed portion (the lower surface of the substrate in the figure) with heated KOH, TMAH, or the like.
[0021]
Next, as shown in FIG. 6, after the silicon nitride film 110 is removed, portions of the polyimide films 104 and 107 that are not covered with the etching mask 108 (mask opening 109 in FIG. 4) are removed by a technique such as RIE. Thus, the movable mirror 111 and the support 112 are completely separated and a torsion spring 113 as an elastic member is formed.
[0022]
Finally, as shown in FIG. 7, after removing the etching mask 108, the exposed portions of the silicon nitride films 102 and 110 are removed to complete the optical scanner.
As described above, in the present embodiment, the torsion spring 113 as the elastic member is formed by covering the etching mask 108 out of the multiple layers (here, two layers) of the elastic film (polyimide films 104 and 107). Since the uncut portion is formed by removing in one step, the side surface of the torsion spring 113 can be formed smoothly, whereby the torsion spring 113 having a uniform shape can be formed. .
[0023]
Further, when the polyimide film 107 is formed, there is no step on the base in the torsion spring 113, so that a uniform film with no film thickness unevenness can be formed, and the dimensional uniformity of the torsion spring 113 is improved.
[0024]
Furthermore, since the etching mask 108 protects the torsion spring 113, when removing the protective film against the etching of the silicon substrate 101 (here, the silicon nitride film 110), the torsion spring 113 is damaged and the element deteriorates. There is no possibility to make it.
[0025]
In the embodiment of the present invention, the silicon nitride film 110 is used as a protective film during substrate etching, but a fluororesin or the like may be used. In this case, as the material of the etching mask 108, a silicon nitride film or the like may be used in addition to the silicon oxide film. The drive coil 103 and the wiring 106 are not limited to aluminum but may be any conductive material such as copper, titanium, or nickel, and the drive coil 103 and the wiring 106 may be made of different materials. In place of the polyimide films 104 and 107, an organic polymer material such as polypropylene, Teflon and nylon may be used.
[0026]
【The invention's effect】
According to the first aspect of the present invention, variation in the dimensions of the elastic member is reduced, so that the element characteristics can be made uniform. Further, the reliability is increased by improving the life of the element by smoothing the side surface of the elastic member.
[0027]
According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the resistance of the electric element is improved.
Further, according to the invention described in claim 3 or 4, in addition to the effect of the invention described in claim 1, it is possible to prevent deterioration of the element in the etching process and the protective film removing process which is a subsequent process. Therefore, the manufacturing yield of the optical scanner is improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining a part of a manufacturing process of an optical scanner according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view for explaining a part of the manufacturing process of the optical scanner according to the embodiment of the invention.
FIG. 3 is a cross-sectional view for explaining a part of the manufacturing process of the optical scanner according to the embodiment of the invention.
4 is a view of FIG. 3 as viewed from the top surface of the substrate. FIG.
FIG. 5 is a cross-sectional view for explaining a part of the manufacturing process of the optical scanner according to the embodiment of the invention.
FIG. 6 is a cross-sectional view for explaining a part of the manufacturing process of the optical scanner according to the embodiment of the invention.
FIG. 7 is a cross-sectional view for explaining a part of the manufacturing process of the optical scanner according to the embodiment of the invention.
FIG. 8 is a perspective view illustrating a configuration example of a conventional optical scanner.
FIG. 9 is a cross-sectional view showing a part of a manufacturing process of a conventional optical scanner.
FIG. 10 is a cross-sectional view showing a part of a manufacturing process of a conventional optical scanner.
FIG. 11 is a cross-sectional view showing a part of the manufacturing process of the conventional optical scanner.
FIG. 12 is a cross-sectional view showing a part of the manufacturing process of the conventional optical scanner.
FIG. 13 is a cross-sectional view showing a part of the manufacturing process of the conventional optical scanner.
FIG. 14 is a cross-sectional view showing a part of the manufacturing process of the conventional optical scanner.
[Explanation of symbols]
101 ... Silicon substrate,
102, 110 ... silicon nitride film,
103 ... Driving coil,
104, 107 ... polyimide film,
105 ... contact hole,
106 ... wiring,
108 ... Etching mask,
109 ... mask opening,
111 ... movable mirror,
112 ... support,
113 ... Torsion spring 200 ... Support,
201 ... movable mirror,
202 ... a torsion spring,
203 ... electrode pad,
204 ... Drive coil,
205 ... magnetic pole,
206 ... Permanent magnet 301 ... Silicon substrate,
302 ... Silicon nitride film,
303 ... drive coil,
304, 307 ... polyimide film,
305 ... contact hole,
306 ... wiring,
308 ... Torsion spring,
309 ... support,
310 ... silicon substrate,
311 ... cap,
312 ... O-ring,
313 ... Etching solution,
314 ... Protective film

Claims (4)

Formed on the surface of the movable plate, a support plate, a movable plate having a reflection surface for reflecting light on at least one surface, an elastic member connecting the movable plate and the support member, and In the method of manufacturing an optical scanner, wherein one surface of a substrate is provided, wherein the movable plate is deflected by elastic deformation generated in the elastic member by generating a force between the support and the movable plate. step and a step of a plurality of layers forming the elastic film on the other surface of the substrate, forming region of the movable plate and the elastic member on the surface of the elastic film to form an etching mask for etching the substrate to wherein the step of forming an etching mask for the elastic film are etched in multiple layers, forming a protective film on the other surface of the substrate including the elastic film etching mask, the substrate And separating form the said support and the movable plate by a portion in which the uncoated substrate etching mask is removed by etching, and removing the protective film, and the elastic film of plural layers, And a step of forming the elastic member by removing a portion not covered with the elastic film etching mask in one step, and a step of removing the elastic film etching mask and the substrate etching mask. A method for manufacturing an optical scanner. 2. The method of manufacturing an optical scanner according to claim 1, further comprising an electric element inside the elastic film. 2. The method of manufacturing an optical scanner according to claim 1, wherein the etching mask for the elastic film is made of a silicon oxide film, and the protective film is made of a silicon nitride film. 2. The method of manufacturing an optical scanner according to claim 1, wherein the etching mask for the elastic film is made of a silicon oxide film or a silicon nitride film, and the protective film is made of a fluororesin.

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