JP2775581B2 - Optical scanner and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanner and a method of manufacturing the same, and more particularly to writing of a facsimile or a printer, adjustment of tracking of an optical pickup, and optical information represented by future optical computing. The present invention relates to an optical scanner that will be used as an important device in the processing field.

[0002]

2. Description of the Related Art In recent years, there has been a trend toward miniaturization, high integration, and low price in AV and OA equipment, and expectations for micromachines using semiconductor process technology have been increasing to meet these needs. In these micromachines, in order to form a three-dimensional structure, bonding, bonding, or a forming method using a sacrificial layer film is often used.

Hereinafter, a conventional one-axis scanning type optical scanner will be described. FIG. 13 is a sectional perspective view showing an example of a conventional optical scanner. In this figure, reference numeral 31 denotes a mirror unit for reflecting and scanning light from a light source, 32 denotes a scanning beam that supports the mirror unit 31 and changes the mirror angle by twisting, and 33 denotes a support base of the mirror unit 31. An outer peripheral portion of the mirror, 34 is a drive electrode for displacing the mirror portion 31 by applying an electrostatic action, 35 is an insulating film covering the drive electrode 34, and 36 is a gap formed between the mirror portion 31 and the drive electrode 34. Reference numeral 37 denotes a glass substrate serving as a base of the optical scanner, and reference numeral 38 denotes a drive electrode outer peripheral lead connection portion.

In manufacturing the conventional optical scanner shown in FIG. 13, the mirror portion 31 and the outer peripheral portion 33 of the Muller are connected to each other at a beam 33 to be integrally formed, and a driving electrode 34 and a glass substrate 37 are formed. After each of the components is formed into a predetermined configuration, the components are finally anodically bonded and assembled.

[0005] The mirror portion is manufactured by using a silicon substrate as a material, and the mirror portion 31 is formed integrally with the beam 32 and the outer peripheral portion 33 of the mirror. The beam 32 supports the mirror portion 31 from both sides, and causes distortion when the voltage is applied to displace the mirror. The mirror outer peripheral portion 33 performs anodic bonding with the glass substrate 37 in the final assembling step. Also,
The back surface of the mirror section 31 is coated with gold. To manufacture the electrode side, first, a pattern of the drive electrode 34 is formed of a metal film on a glass substrate 37, and an insulating film 35 is formed thereon. In addition, in order to form a gap between the mirror section 31 and the drive electrode 34, the gap forming section 36 is formed on the insulating film 35 using a material such as Pyrex glass that can be anodically bonded.

Finally, the mirror section and the electrode section are assembled by anodic bonding. At this time, the gap forming part 36 and the mirror outer peripheral part 33 are joined, but the gap forming part 36 and the mirror part 31 are not joined. This is because the back surface of the mirror portion 31 is coated with gold, and the fact that gold is not anodically bonded to Pyrex glass is used.

Next, the operation of the optical scanner configured as described above will be described. The mirror unit 31
By receiving an electrostatic force by alternately applying a voltage to the drive electrode 34, the beam 32 is twisted, and an operation of scanning in one direction is performed with the gap forming portion 36 at the center lower portion of the mirror portion 31 as a fulcrum. Further, the scanning angle can be controlled by an applied voltage in a scanning range limited by the gap forming section 36.

[0008]

However, in the above-mentioned conventional configuration, in the manufacture of the optical scanner, assembly is finally required, and bonding and bonding must be performed. Adhesion is limited in the method of application in the production of micromachines such as optical scanners, and the properties are affected by the presence of an elastic body such as an adhesive. Joining has the disadvantage that the combined materials that can be joined are limited to several types of materials, such as Pyrex glass and silicon, and that it is difficult to align the joining positions with a small machine.

[0009] Further, in the conventional fabrication of micromachines, 3
A sacrificial layer film is often used to obtain a three-dimensional structure. Although a silicon oxide film is often used as the sacrificial layer film, a hydrofluoric acid-based solution is required to remove the silicon oxide film, and there is a concern that it may attack other structural materials.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an optical scanner which can be easily manufactured and which can realize a high-performance optical scanner, and a method of manufacturing the same. It is.

[0011]

According to the present invention, in order to achieve the above object, an electrode is formed on the surface and the substrate is covered with an insulating layer, and a certain gap is provided between the substrate and the electrode with the insulating film interposed therebetween. An optical scanner comprising a mirror portion which is disposed to face and is displaceably connected to and supported by the substrate at one end portion, wherein the mirror portion has a wedge at a portion connected to the substrate.
And a flat shape that expands from this connection to the front
Cells with multiple shapes, constant laterally alternately
Are arranged in an array structure with a gap between
In other words, the gist is that the mirror portion is displaced in the electrode direction with the substrate supporting portion as a fulcrum by applying a voltage between the electrode and the mirror portion.

[0012] The present invention also relates to a method for manufacturing a substrate comprising an insulating material.
The electrode inversion pattern is formed with a film that can be partially removed.
Forming, and using the partially removable film as a mask,
Etching a substrate; and removing the substrate and the partial
Forming a metal film on a mixture of removable films
Remove the partially removable film and leave the metal film only on the electrode part.
Process to flatten the entire substrate even after electrode formation.
In addition, an insulating film is formed on the mixture of the electrodes and the substrate.
Forming a polyimide film as a sacrificial layer film on the insulating film.
Resin will later form an electrostatic gap between the electrode and the mirror
Forming the shape and heat curing the polyimide resin
A film forming step, and a
Forming a thin film serving as a mirror portion;
Forming a shape, and removing the sacrificial layer film to form an electrode
Forming an electrostatic gap between insulating parts via an insulating film
The gist is a method for manufacturing an optical scanner having:

[0013]

According to the optical scanner of the present invention , an insulating layer is coated on an electrode.
After forming a sacrificial layer film on this insulating layer,
A metal thin film is formed thereon, and then the sacrificial layer film is removed.
The gap is formed by interposing an insulating film between the electrode and the mirror.
In the following procedure, an electrode is formed on the surface and this is
The coated substrate and the electrode are fixed with the insulating film interposed therebetween.
They are arranged facing each other with a gap, and at one end,
Optical scan from the mirror section, which is connected to and supported by the plate
The mirror portion is provided at a portion connected to the substrate.
Constricted and expanded from this connection to the front
Multiple cells with a planar shape, alternating laterally
Are arranged in an array structure with a certain gap
And applying a voltage between the electrode and the mirror section.
Then, the mirror is displaced in the electrode direction with the substrate support as a fulcrum.
High-performance optical scanner
It can be easily manufactured. Also especially sacrificed
Polyimide resin is used as the sacrificial layer
Selection of the sacrificial layer film by setting the boiling point of the polyimide resin or lower
Easy to remove and form easily, and assembling such as bonding and joining
Technology to reduce the production time of optical scanners without the need for technology
One. Further, the solvent of the polyimide resin has almost no adverse effect on other structural materials as compared with the hydrofluoric acid-based solution.

[0014]

【Example】

(Embodiment 1) FIGS. 1 to 11 are views showing a first embodiment of the present invention. 1A and 1B are external views of an optical scanner according to the present invention, in which FIG. 1A is a partial plan view of an optical scanner having an array structure, and FIG. 1B is a perspective view when FIG. Is shown. 2 to 10 show a method of manufacturing the optical scanner according to the present invention.

FIG. 1 is an enlarged view of three rows in which a plurality of minute optical scanners are arranged. In this figure, reference numeral 14 denotes an electrode disposed on an insulating substrate 11 made of an insulating material such as glass, 20 denotes a mirror disposed opposite to the electrode 14 and scans by reflecting light from a light source, 21 This is a gap formed between the electrode 14 and the mirror section 20.

In this embodiment, each mirror section 20 of the optical scanner has a so-called cantilever structure in which the base is integrally connected to the insulating substrate 11 and projects above the electrode 14. The mirror section 20 is provided on the insulating substrate 11.
A plurality of cells having a planar shape that is constricted at the connecting portion to and expanded from the connecting portion toward the front are combined alternately in front and rear, and are arranged with a constant gap in the lateral direction, forming an array structure. Are arranged.
Since the mirror section 20 is formed with a certain gap 21 from the electrode 14 formed on the substrate, a voltage is applied to the electrode 14 below the mirror section 20 to lower the mirror section 20 by electrostatic force. Can be displaced.

Steps for fabricating such an optical scanner will be sequentially described with reference to FIGS. In these figures, reference numeral 11 denotes an insulating substrate, 12 denotes a photoresist layer, 13 denotes a metal film, 14 denotes an electrode, 15 denotes an insulating film,
Reference numeral 6 denotes a sacrificial layer film, 17 denotes a photoresist layer, 18 denotes a metal film serving as a mirror portion, 19 denotes a photoresist layer, 20 denotes a mirror portion, and 21 denotes a gap.

As a first step, as shown in FIG. 2, an inverted pattern of electrodes is formed on an insulating substrate 11, for example, Pyrex glass with a photoresist layer 12, and the Pyrex glass is etched with hydrofluoric acid using this as a mask. The insulating substrate 11 initially has a laterally T-shaped notch as shown in FIGS. 2 (a) and 2 (b). As a second step, as shown in FIGS. 3A and 3B, an aluminum metal film 13 is
A layer corresponding to the processing depth of Pyrex glass is laminated on the entire surface by PVD (physical vapor deposition) processing.

As a third step, as shown in FIGS. 4A and 4B, lift-off is performed to remove the resist, and an electrode 14 is formed while leaving the metal film 13 only on the electrode shape portion. The entire insulating substrate 11 including the electrodes 14 is made flat.

As a fourth step, as shown in FIGS. 5A and 5B, a silicon oxide film as an insulating film 15 is laminated on the entire surface of the electrode 14 by PVD. A polyimide resin is formed thereon by spin coating as a sacrificial layer film 26. In this embodiment, the resin is spin-coated using a polyimide resin RN812 manufactured by Nissan Chemical Industries, Ltd., preliminarily dried at a temperature of 80 ° C. for 5 minutes, and then cured at 180 ° C. for 30 minutes and a half.

As a fifth step, as shown in FIGS. 6A and 6B, a positive type photoresist layer 17 is formed on the sacrificial layer film 16 by spin coating, and then the mirror portion 2 is formed.
Patterning is performed so as to form an electrostatic gap 21 between 0 and the electrode 14. The patterning is performed with a developer of a positive photoresist, and the photoresist layer 17 and the sacrifice layer film 16 of the polyimide resin are simultaneously developed. As a sixth step, as shown in FIGS. 7A and 7B, a heat treatment is performed after the photoresist layer 17 is stripped with isopropyl alcohol. Polyimide resin RN81 used in this example
Since the solvent of No. 2 is N-methylpyrrolidone and the boiling point is 202 ° C., the heat treatment is performed in an oven at 200 ° C. for 1 hour.

As a seventh step, as shown in FIGS. 8A and 8B, aluminum is formed on the entire surface of the metal film 18 serving as the mirror portion 20 by PVD.

As an eighth step, as shown in FIGS. 9A and 9B, a photoresist layer 19 is applied on the metal film 18 to form an inverted pattern of the mirror section 20.

As a ninth step, as shown in FIGS. 10A and 10B, the metal film 18 is etched with 50% phosphoric acid using the photoresist layer 19 as a mask, and the mirror portion 20 is etched.
To get the shape.

As a tenth step, the sacrificial layer film 16 of polyimide is dissolved and removed with N-methylpyrrolidone as a solvent to form a gap 21 between the mirror section 20 and the electrode 14.

The feature of this embodiment lies in the setting of the film forming temperature of the polyimide resin used as the sacrificial layer film 16. Normally, the above polyimide resin RN812 is completely cured by 300 times.
Performing at 30 ° C. for 30 minutes, and after complete curing, it cannot be removed unless a strong alkaline solution is used. However, by using the film forming temperature of this embodiment, it can be easily removed by using a polyimide resin solvent. Since the solvent of RN812 is N-methylpyrrolidone and its boiling point is 202 ° C., the film formation temperature may be lower than this boiling point.

FIG. 11 shows the result of thermogravimetric analysis of RN812. Thermogravimetric analysis measures the change in weight of a substance due to heating, and is used to determine the temperature at which volatile components and the like separate. In FIG. 11, around 150 ° C. and 21
A large change is observed around 0 ° C. The change up to around 150 ° C. is due to dehydration by imidization of the polyimide, and the change around 210 ° C. is due to evaporation of the solvent. From the results of the thermogravimetric analysis, it was confirmed that the evaporation of the solvent actually occurred near the boiling point. In addition, an experiment of dissolution in a solvent was performed, and it was confirmed that those heat-treated at a temperature lower than the boiling point of the solvent were soluble in the solvent, but those heat-treated at a temperature higher than the boiling point became insoluble in the solvent.

The solvent for the polyimide resin is an organic solvent that is less harmful than an acid or alkali solution, and there is no concern that other structural materials will be attacked when the sacrificial layer film 16 is removed in the final step. The removal rate of polyimide by this solvent is high, and 3 μm / mi with N-methylpyrrolidone at 40 ° C.
n. Conventionally, silicon oxide is often used as the sacrificial layer film 16 in the fabrication of micromachines. However, as an example of removing the silicon oxide film, 25 ° C., P etch (70% nitric acid: 49% hydrofluoric acid: water = 2) : 3: 60) and 4 to 12 angstroms / sec (WERNER KERN AN)
D CHERLA. DECKERT “THIN F
ILM PROCESSES ").

In the present embodiment, the formation of the sacrificial layer film 16 is performed by spin coating, but it is also possible to apply by spraying.

Further, the solvent of the polyimide resin used in this example was N-methylpyrrolidone, but it is not limited to this solvent. Others include butyrolactone, N, N-
Dimethylformamide, N, N-dimethylacetamide, N-vinylpyrrolidone, dimethylsulfoxide,
m-cresol or the like is used.

As described above, according to this embodiment, a polyimide resin is used for the sacrificial layer film 16 and the curing temperature is set to be equal to or lower than the boiling point of the solvent. Not only can it be easily removed and the forming method is easy, but also a minute machine such as an optical scanner can be manufactured without using an assembling technique such as bonding or joining.

(Embodiment 2) As a second embodiment of the present invention, a method for manufacturing an optical scanner using a positive photosensitive polyimide resin for the sacrificial layer film 16 will be described.

As the positive photosensitive polyimide resin, there is a positive photosensitive polyimide RN901 manufactured by Nissan Chemical Industries, Ltd.
Was used.

The steps for fabricating the optical scanner are almost the same as those in the first embodiment. However, since the polyimide resin itself has photosensitivity, the photo-resist is formed on the polyimide resin in FIGS. 6A and 6B. The step of forming the resist film 17 can be omitted. Since the solvent of the polyimide resin of this example is butyrolactone and the boiling point is 204 ° C., the film formation in FIGS. 7A and 7B was also performed at 200 ° C. in Example 2.

FIG. 12 shows the result of thermal analysis of the polyimide resin RN901 manufactured by Nissan Chemical Industries, Ltd. used in this example to confirm that the solvent of the polyimide resin was evaporated at its boiling point. In FIG. 12, weight changes are observed around 150 ° C. and around 200 ° C. The change around 150 ° C. is due to dehydration inside RN901,
The change around 00 ° C. is due to evaporation of the solvent. When the RN901 was subjected to a heat treatment for forming a film at a temperature lower than the boiling point of the solvent, it was again soluble in the solvent. However, when a film was formed at a temperature higher than the boiling point, it became insoluble in the solvent. That was confirmed.

The butyrolactone solvent for the polyimide resin is an organic solvent that is less harmful than an acid or alkali solution, and does not have a risk of attacking other structural materials when removing the sacrificial layer film in the final step. In addition, the removal rate of polyimide by this solvent is high, and butyrolactone at 40 ° C. is 5 μm.
/ Min.

The solvent for the polyimide resin used in this example was butyrolactone, but the solvent is not limited to this. Others include N-methylpyrrolidone, N, N-
Dimethylformamide, N, N-dimethylacetamide, N-vinylpyrrolidone, dimethylsulfoxide,
m-cresol or the like is used.

As described above, according to this embodiment, the positive photosensitive polyimide resin is used as the sacrificial layer film 16, so that the photoresist film forming step is reduced by patterning the polyimide resin during the manufacturing process of the optical scanner. In addition, by setting the curing temperature of the polyimide resin to be equal to or lower than the boiling point of the solvent, the sacrificial layer film 1 can be formed without invading other structural materials.
6 can be selectively removed and the forming method is not only easy, but also a minute machine such as an optical scanner can be manufactured without using an assembling technique such as adhesion or bonding.

[0039]

As described above, according to the present invention, after covering an electrode with an insulating layer, a sacrificial layer film is formed on the insulating layer, and then a metal thin film is formed thereon. By removing the layer film and forming a gap by interposing an insulating film between the electrode and the mirror, a substrate is formed on the surface and covered with an insulating layer, and the electrode is fixed with the insulating film interposed. An optical scanner is constituted by a mirror portion which is disposed to face the gap with a gap, and which is connected and supported at one end thereof so as to be displaceable to the substrate , wherein the mirror portion is a portion connected to the substrate.
At the neck and expand from the connection to the front.
Multiple cells with open planar shapes, alternately front and back
Arranged in an array structure with a certain gap in the horizontal direction
Are columns, by applying a voltage between the electrodes and the mirror unit, the mirror unit is, because of manufacturing a light scanner can be displaced in the electrode direction fulcrum substrate support, easily fabricated performance optical scanner Will be able to In particular, by using a polyimide resin as the sacrificial layer film and setting the film forming temperature to be equal to or lower than the boiling point of the polyimide resin, it is easy to selectively remove and form the sacrificial layer film, and requires an assembling technique such as adhesion and bonding. It is useful for shortening the manufacturing time of the optical scanner.

[Brief description of the drawings]

FIG. 1A is a partial plan view showing an embodiment of an optical scanner according to the present invention. FIG. 1B is a partial sectional perspective view showing an embodiment of an optical scanner according to the present invention.

FIG. 2A is a cross-sectional view illustrating a first step of a manufacturing method according to a first embodiment of the optical scanner according to the present invention. FIG. 2B is a sectional view illustrating a manufacturing method according to the first embodiment of the optical scanner according to the present invention. Plan view showing first step

FIG. 3A is a cross-sectional view showing a second step of the manufacturing method according to the first embodiment of the optical scanner according to the present invention. FIG. 3B is a sectional view showing the manufacturing method according to the first embodiment of the optical scanner according to the present invention. Plan view showing second step

FIG. 4A is a cross-sectional view illustrating a third step of the manufacturing method according to the first embodiment of the optical scanner according to the present invention. FIG. 4B is a sectional view illustrating the manufacturing method according to the first embodiment of the optical scanner according to the present invention. Plan view showing third step

FIG. 5A is a cross-sectional view showing a fourth step of the manufacturing method according to the first embodiment of the optical scanner according to the present invention. FIG. 5B is a sectional view showing the manufacturing method according to the first embodiment of the optical scanner according to the present invention. Plan view showing fourth step

FIG. 6A is a sectional view showing a fifth step of the manufacturing method of the optical scanner according to the first embodiment of the present invention. FIG. 6B is a sectional view showing the manufacturing method of the optical scanner according to the first embodiment of the present invention. Plan view showing fifth step

FIG. 7A is a cross-sectional view showing a sixth step of the manufacturing method of the optical scanner according to the first embodiment of the present invention. FIG. 7B is a sectional view showing the manufacturing method of the optical scanner according to the first embodiment of the present invention. Plan view showing a sixth step

FIG. 8A is a sectional view showing a seventh step of the manufacturing method according to the first embodiment of the optical scanner according to the present invention. FIG. 8B is a sectional view showing the manufacturing method according to the first embodiment of the optical scanner according to the present invention. Plan view showing a seventh step

FIG. 9A is a sectional view showing an eighth step of the manufacturing method according to the first embodiment of the optical scanner according to the present invention. FIG. 9B is a sectional view showing the manufacturing method according to the first embodiment of the optical scanner according to the present invention. Plan view showing an eighth step

FIG. 10A is a sectional view showing a ninth step of the manufacturing method according to the first embodiment of the optical scanner according to the present invention. FIG. 10B is a sectional view illustrating the manufacturing method according to the first embodiment of the optical scanner according to the present invention. Plan view showing ninth step

FIG. 11 is a graph showing the results of thermogravimetric analysis of a polyimide resin used as a sacrificial layer film in the method for manufacturing an optical scanner according to the first embodiment of the present invention.

FIG. 12 is a graph showing the results of thermogravimetric analysis of a polyimide resin used as a sacrificial layer film in the method for manufacturing an optical scanner according to the second embodiment of the present invention.

FIG. 13 is a perspective view showing an example of the structure of a conventional optical scanner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Insulating substrate 12 Photoresist layer 13 Metal film 14 Electrode 15 Insulating film 16 Sacrificial layer film 17 Photoresist layer 18 Metal film 19 Photoresist film 20 Mirror part 21 Gap

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 26/10 G02B 26/08

Claims (6)

(57) [Claims] A substrate having an electrode formed on a surface thereof; an insulating film laminated on the electrode; and an opposing electrode disposed at a certain gap from the electrode with the insulating film interposed therebetween. And a mirror portion connected and supported so as to be displaceable to the substrate.
Constricted and expanded from this connection to the front
Multiple cells with a planar shape, alternating laterally
Are arranged in an array structure with a certain gap
And which, by applying a voltage between the electrodes and the mirror unit, optical scanner, wherein a mirror section is displaced in the electrode direction the portion supported by the substrate as a fulcrum. 2. A step of forming an inversion pattern of an electrode with a partially removable film on a substrate made of an insulating material; and a step of etching the substrate using the partially removable film as a mask. The step of forming a metal film on the substrate and the partially removable film are mixed, and the step of removing the partially removable film and leaving the metal film only at the electrode portion, even after the electrode formation Flattening the entire substrate, further forming an insulating film on the electrode and the substrate are mixed, and a polyimide resin as a sacrificial layer film on the insulating film, and later an electrostatic gap between the electrode and the mirror portion. Forming the polyimide resin by thermosetting, forming a thin film to be a mirror part on which the insulating film is mixed, and forming the thin film into a mirror part shape And the sacrifice A method for manufacturing an optical scanner, comprising a step of removing a layer film and forming an electrostatic gap between an electrode and a mirror portion via an insulating film. 3. The method for manufacturing an optical scanner according to claim 2, wherein the sacrificial layer film is formed of a polyimide resin, and a film forming temperature is set to be equal to or lower than a boiling point of a solvent of the polyimide resin. 4. The method of manufacturing an optical scanner according to claim 2, wherein the sacrificial layer film is formed of a positive photosensitive polyimide resin, and the film formation temperature is set to 130 ° C. or higher and the boiling point of the polyimide resin solvent or lower. . 5. A method according to claim 3 or 4 manufacturing method of the optical scanner according to the removal of the sacrificial layer film and performing a solvent of the polyimide. 6. The method of claim 3 or 4 manufacturing method of the optical scanner according to, characterized in that the effect formation of the sacrificial layer film spin coating.