JPH08146209A - Production of curved surface grating - Google Patents

Abstract

PURPOSE: To make possible the drawing of submicron sizes by applying a photosensitive agent on a substrate previously worked to a curved surface and exposing this photosensitive agent by plotting with a laser beam, then developing the photosensitive agent. CONSTITUTION: The glass substrate 1 one surface of which is formed as a plane and the other surface as a concave spherical surface is heated to sufficiently remove moisture and thereafter, the spherical surface side is spin coated with a photoresist 2 of a positive type and is heated at a prescribed temp. by which the solvent is evaporated away. Next, this photoresist 2 is plotted with straight lines by the beam converted by a laser plotter 3. This laser plotter 3 is provided with a sensor 5 on a stage 4 to be placed with the substrate 1 in such a manner that the driving of this stage 4 is controlled in a horizontal direction. A motor driver 7 and a motor 8 are connected via a computer 6. The laser beam oscillated from a laser oscillator 9 is focused always to the curved surface of the front surface of the photoresist 2 by the function of an autofocus 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a curved surface grating for forming a grating on a curved surface of a substrate.

[0002]

2. Description of the Related Art Conventionally, as disclosed in JP-A-62-30201, interference fringes are formed on a spherical substrate coated with photoresist by an aspherical interference exposure method using an aspherical wave as an interference exposure wavefront. After exposure, the photoresist pattern is obtained by developing. Then, as shown in the Shimadzu product catalog (“Shimadzu optical element” C128-0043), the substrate is subjected to ion beam etching from an oblique direction to process a sawtooth grating on the spherical surface.

[0003]

However, the above-mentioned conventional method requires a complicated and large-scale device called an interference exposure device, and since the interference fringes are exposed, if an interference fringe of a desired pattern is generated, There is a problem that it is necessary to design and manufacture a corresponding complex interference optical system or optical element, and pattern restrictions may occur depending on the feasibility thereof. In addition, there is a problem that extremely strict environmental management such as air flow, temperature, and vibration is required to stabilize the interference fringes.

The present invention has been made in view of the above conventional problems. The invention according to claim 1 is a simple device.
Moreover, it is an object of the present invention to provide a method of manufacturing a curved surface grating that can form a grating having an arbitrary pattern on a curved surface without requiring strict environmental management.

In addition to the above objects, it is an object of the invention according to claim 2 or 3 to provide a method for manufacturing a curved grating which can easily realize blazing.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 applies a photosensitizer to a substrate which has been processed into a curved surface in advance when manufacturing a curved grating, Was exposed by laser beam drawing, and then the exposed photosensitive agent was developed to form irregularities.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the laser beam is applied from a direction inclined with respect to the center line of the substrate.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention according to (1), at least two laser beams having different optical axes and the same condensing point are used.

[0009]

In the present invention, a laser beam is used, and since it is narrowed down to a submicron size by narrowing it down with an optical system, it is possible to draw a line having a width of a submicron beam size at the minimum. Moreover, the focus of the laser beam can always follow the curved surface by the autofocus function. Therefore, not only a spherical surface but also a curved surface having a change in every height direction can be drawn in the same manner as a flat surface. Furthermore, by giving a grating pattern as coordinate data, an arbitrary pattern can be drawn by automatically driving the precision stage on which the substrate is mounted in the XY directions. Further, since the pattern formation is not based on the interference fringes but is based on the XY drive of the stage as described above, the environmental management is not as strict as the interference exposure. Also, the apparatus does not need to be designed and changed each time as in the case of interference exposure, and it is possible to cope with all kinds of equipment if there is one apparatus.

By applying one or a plurality of laser beams obliquely to the substrate, asymmetric exposure is performed with respect to the center of the substrate, and a grating having an asymmetric cross-sectional shape can be formed in the same process.

[0011]

【Example】

[Embodiment 1] This will be described with reference to FIGS. A glass substrate 1 having a flat surface on one side and a concave spherical surface having a curvature of 85 mm and a diameter of 40 mm on one surface is heated to sufficiently remove water, and then a positive photoresist 2 is spin-coated on the spherical surface side to a thickness of 1 μm. The solvent was removed by heating at a predetermined temperature. The thickness is approximately 0.9 μm. Next, this photoresist is shown in FIG.
The beam was narrowed to 1.1 μm by a He-Cd laser drawing device (LBDD-29T / T, manufactured by Hakuto Co., Ltd.) 3 having a wavelength of 442 nm shown in 1 and a straight line was drawn at a pitch of 2.2 μm.

In the laser drawing apparatus of FIG. 2, a sensor 5 is provided on the stage 4 so that the stage 4 on which the substrate 1 is placed can be driven and controlled in the horizontal direction (XY directions), and a computer 6 is used. The motor driver 7 and the motor 8 are connected. On the other hand, the laser beam oscillated from the laser oscillator 9 has an autofocus 10
With this function, it is possible to always focus on the curved surface of the photoresist 2 via the motor driver 11 and the motor 12. Reference numeral 13 is a power meter, and 14 is a condenser lens. In the present invention,
The type of drawing device that can be used is not limited to this.

The drawing speed was 2 mm / sec. By appropriately setting the laser intensity, the photoresist 2 was exposed to a depth of 0.2 μm from the surface (FIG. 3). Then, this was developed to form sinusoidal unevenness having a depth of 0.2 μm on the surface of the photoresist 2 (FIG. 4). Then, the photoresist 2 was cured by heating. Next, the aluminum reflection film 15 is formed on the surface of the photoresist 2 by a known vacuum deposition method to a thickness of 500.
An angstrom film was formed (FIG. 5). As described above, a reflective concave grating was obtained.

According to the method of this embodiment, when the photoresist 2 is exposed by the laser beam, the laser intensity decreases from the surface of the photoresist 2 to the substrate 1 side, and the bottom surface becomes rounded. A sinusoidal groove as shown in FIG. 4 can be formed by the effect of the edge of the photoresist 2 dripping.

[Second Embodiment] A second embodiment will be described with reference to FIGS. A quartz glass substrate 1 having a flat surface on one side and a concave spherical surface with a curvature of 93 mm and a diameter of 40 mm on one side is heated to sufficiently remove moisture, and then a positive photoresist 2 of 1 μm is provided on the spherical surface side.
Was spin coated and heated at a predetermined temperature to remove the solvent. Next, this photoresist is applied to a wavelength of 442 nm.
Beam of 1.5μm with He-Cd laser drawing device
And drawn an arc-shaped line in which the pitch gradually changes from 3.4 μm to 3.0 μm. Drawing speed is 3mm /
I went in sec. By properly setting the laser intensity, the bottom surface of the photoresist 2 was exposed so as to be sufficiently exposed (FIG. 6). Then, by developing this, the unevenness of the photoresist 2 was formed (FIG. 7). Then, the photoresist 2 was cured by heating. Next, the quartz glass substrate 1 was etched to a depth of 0.2 μm by reactive ion etching (FIG. 8). Then, the photoresist 2 was removed by oxygen plasma ashing. Then, a rectangular lattice having a depth of 0.2 μm was formed on the surface of the glass substrate 1 (FIG. 9). Next, the aluminum reflection film 15 is formed on the surface of the glass substrate 1 by a known vacuum deposition method to a thickness of 500.
An angstrom film was formed (FIG. 10). As described above, a reflective concave grating was obtained.

According to the method of this embodiment, since the reactive ion etching has a high directivity, a rectangular lattice having steep side surfaces can be obtained. Further, since the grating obtained in this example is made of glass and aluminum, it has high heat resistance and chemical resistance.

[Third Embodiment] A third embodiment will be described with reference to FIGS. A glass substrate 1 having a flat surface on one side and a convex spherical surface with a curvature of 85 mm and a diameter of 100 mm is heated to sufficiently remove moisture, and then a positive photoresist 2 of 1 μm is provided on the spherical surface side.
Was spin coated and heated at a predetermined temperature to remove the solvent (FIG. 11). Then, the photoresist 2 was irradiated with a beam of 0. 3 by an Ar laser drawing device having a wavelength of 351 nm.
A line was drawn in a 40 mm square area with a pitch of 1.8 μm and a size of 8 μm. The drawing speed was 1 mm / sec. By properly setting the laser intensity, the bottom surface of the photoresist 2 was exposed so as to be sufficiently exposed.
Then, by developing this, unevenness was formed on the photoresist 2. Then, the photoresist 2 was cured by heating. Next, the quartz glass substrate 1 was etched to a depth of 0.2 μm by reactive ion etching.
Then, the photoresist 2 was removed by oxygen plasma ashing. Then, the depth of 0.
A 2 μm rectangular grid was formed (FIG. 12).

Next, the glass substrate 16 having a flat surface on one side and a concave spherical surface having a curvature of 85 mm and a diameter of 40 mm on one side is heated to remove water, and the concave side is subjected to silane coupling treatment.
The ultraviolet curable resin 17 was applied. Thereafter, the convex glass grating obtained as described above was placed in contact with the ultraviolet curable resin 17, and the grating was transferred to the ultraviolet curable resin 17. Next, the resin 17 was cured by irradiation with ultraviolet rays (FIG. 13), and the convex grating was separated from the resin 17. Thus, the concave glass substrate 16
A concave grating having a diffraction grating formed on the surface thereof with an ultraviolet curable resin 17 was obtained (FIG. 14).

According to the method of the present embodiment, if one grating is formed by laser beam drawing, the grating can be manufactured as a stamper with good mass productivity.

[Embodiment 4] A description will be given with reference to FIGS. A glass substrate 1 having a flat surface on one side and a concave spherical surface having a curvature of 85 mm and a diameter of 100 mm is heated to sufficiently remove moisture, and then a positive type photoresist 2 having a thickness of 1 μm is provided on the spherical surface.
Was spin coated and heated at a predetermined temperature to remove the solvent. Next, this photoresist 2 is formed with a wavelength of 351 nm.
The beam was narrowed to 0.8 μm by the Ar laser drawing device of No. 2 and a straight line was drawn in a 40 mm square area at a pitch of 1.8 μm. The drawing speed was 1 mm / sec. By appropriately setting the laser intensity, the photoresist 2 was exposed to a depth of 0.2 μm from the surface thereof. Then, by developing this, 0.2 μm sinusoidal unevenness was formed on the surface of the photoresist 2.
Then, the photoresist 2 was cured by heating (FIG. 4).
Next, a conductive film 18 having a thickness of 500 angstrom was formed on the surface of the photoresist 2 by a known vacuum deposition method (see FIG. 1).
5). Further, this was used as a master to perform electroforming reversal by a known electroforming reversal technique to obtain a nickel convex grating stamper 19 (FIG. 16).

Next, the glass substrate 16 having a flat surface on one side and a concave spherical surface having a curvature of 85 mm and a diameter of 40 mm on one side is heated to remove water, and the concave side is subjected to silane coupling treatment.
The ultraviolet curable resin 17 was applied. Next, the stamper 19 made of nickel having the convex surface inverted by electroforming was placed in contact with the ultraviolet curable resin 17 to transfer the irregularities to the ultraviolet curable resin 17 (FIG. 17). Then, ultraviolet rays were irradiated through the glass substrate 16 to cure the ultraviolet curable resin 17, and the stamper 19 was separated from the resin 17 (FIG. 18).
Next, a reflection film 15 of aluminum was formed on the surface of the resin 17 by a known vacuum deposition method to a thickness of 500 angstrom. In this way, a reflection type concave surface grating in which irregularities were formed by the ultraviolet curable resin 17 on the surface of the concave glass substrate 16 was obtained (FIG. 19).

According to the method of this embodiment, if one grating is produced by laser beam drawing, the nickel stamper is electroformed by using it as a master to make a nickel stamper, and the grating is manufactured with resin with good mass productivity. can do.

[Embodiment 5] Only the points different from Embodiment 2 will be described with reference to FIGS. The process is the same as in Example 2 up to the step of obtaining a photoresist pattern on the concave spherical substrate (FIG. 7). Next, the surface of the quartz glass substrate 1 was irradiated with an ion beam from an oblique direction by reactive ion beam etching (FIG. 20). As a result, the quartz glass substrate 1 and the photoresist 2 are simultaneously etched, and the pitch is 3.0 to 3.4 μm and the depth is 0.5 μm.
Blazed gratings were formed on the surface of the quartz glass substrate 1. Through the above steps, a transmissive concave grating was obtained (FIG. 21).

According to the method of this embodiment, since the reactive ion beam etching has high directivity and the incident angle with respect to the substrate can be set, a blazed grating can be obtained.

[Sixth Embodiment] A sixth embodiment will be described with reference to FIGS. One side is flat and one side is one side with a curvature of 85m
FIG. 22 shows a glass substrate 1 having a concave toric surface of m and a curvature of 93 mm in a direction orthogonal to the m, and a diameter of 40 mm.
After heating this to sufficiently remove water, a positive photoresist 2 was spin-coated on the spherical surface to a thickness of 1 μm and heated at a predetermined temperature to remove the solvent. Next, the beam of the photoresist 2 was narrowed to 1.1 μm by a He—Cd laser drawing device 3 (FIG. 2) having a wavelength of 442 nm,
Straight lines were drawn at a pitch of 2.2 μm. Drawing speed is 2mm
/ Sec. By appropriately setting the laser intensity, the photoresist 2 was exposed to a depth of 0.2 μm from the surface (FIG. 3). Then, this was developed to form sinusoidal unevenness having a depth of 0.2 μm on the surface of the photoresist 2 (FIG. 4). Then, the photoresist 2 was cured by heating. Next, an aluminum reflection film 15 of 500 angstrom was formed on the surface of the photoresist 2 by known vacuum deposition (FIG. 5). In this way, a reflective concave toric grating was obtained.

According to the method of this embodiment, a grating having an arbitrary curved surface other than a spherical surface can be obtained.

[Embodiment 7] A description will be given with reference to FIGS. One side is flat and one side has a central curvature of 85 mm and a peripheral curvature of 9
After heating a glass substrate 1 having a concave aspherical surface of 3 mm and a diameter of 40 mm to sufficiently remove moisture, a positive photoresist 2 is spin-coated on the spherical surface to a thickness of 1 μm and heated at a predetermined temperature. To remove the solvent. Next, the beam of this photoresist 2 was narrowed to 1.1 μm by a He-Cd laser drawing device 3 (FIG. 2) having a wavelength of 442 nm, and a pitch of 2.
A straight line was drawn at 2 μm. The drawing speed was 2 mm / sec. By appropriately setting the laser intensity, the photoresist 2 was exposed to a depth of 0.2 μm from the surface (FIG. 3). After that, by developing this, a depth of 0.2 μ is formed on the surface of the photoresist 2.
A sinusoidal unevenness of m was formed (FIG. 4). Then, the photoresist 2 was cured by heating. Next, a reflection film 1 of aluminum is formed on the surface of the photoresist 2 by known vacuum deposition.
5 was formed into a 500 angstrom film (FIG. 5). In this way, a reflective concave toric grating was obtained.

According to the method of this embodiment, a grating having an aspherical surface can be obtained.

[Embodiment 8] A description will be given with reference to FIGS. 23 to 25. A glass substrate 1 having a flat surface on one side and a concave spherical surface with a curvature of 85 mm and a diameter of 40 mm on one side is heated to sufficiently remove moisture, and then a positive type photoresist 2 of 1 μm is provided on the spherical surface side.
Was spin coated and heated at a predetermined temperature to remove the solvent. Next, the substrate 1 coated with this photoresist 2
Was placed on the stage 4 of the He-Cd laser drawing apparatus 3 (FIG. 2) having a wavelength of 442 nm with an inclination of 30 °, the beam was narrowed to 1.1 μm, and straight lines were drawn at a pitch of 2.2 μm. The drawing speed was 2 mm / sec. By appropriately setting the laser intensity, the photoresist 2 was exposed to a depth of 0.2 μm from the surface (FIG. 23). By exposing the photoresist 2 from a direction inclined with respect to the normal to the surface of the photoresist 2, the exposed portion becomes an asymmetric region, and then the photoresist 2 is developed to have a depth of 0. Blaze-shaped irregularities of 2 μm were formed (FIG. 24). And photoresist 2
Was cured by heating. Next, a reflection film 15 of aluminum having a thickness of 500 angstrom was formed on the surface of the photoresist 2 by known vacuum deposition (FIG. 25). As described above, a reflective concave blazed grating was obtained.

According to the method of this embodiment, the laser beam is tilted with respect to the normal line to the substrate for exposure, so that blazing can be realized.

[Embodiment 9] This will be described with reference to FIGS. 26 to 28. A glass substrate 1 having a flat surface on one side and a concave spherical surface having a curvature of 85 mm and a diameter of 40 mm on one surface is heated to sufficiently remove water, and then a positive photoresist 2 is spin-coated on the spherical surface side to a thickness of 1 μm. The solvent was removed by heating at a predetermined temperature. Next, the laser drawing apparatus used in this embodiment shown in FIG. 26 will be described. This apparatus is configured to split a laser beam into two light beams by a beam splitter 20 and to focus both beams on the same point at different angles with respect to the substrate 1. That is, the laser beam emitted from the condenser lens 14 is divided into two beams by the beam splitter 20, the beam reflected by the beam splitter 20 is reflected by the convex mirror 21, and the two beams are condensed at one point. It has become.

The photoresist 2 is replaced with the wavelength 4 of the above construction.
The beam was narrowed to 1.1 μm by a 42 nm He-Cd laser drawing device 22 and a straight line was drawn at a pitch of 2.2 μm. The drawing speed was 2 mm / sec. By appropriately setting the laser intensity, the photoresist 2 was exposed to a depth of 1 μm from the surface (see FIG. 2).
7). Then, this was developed to form blaze-shaped unevenness having a depth of 1 μm on the surface of the photoresist 2 (FIG. 28). Then, the photoresist 2 was cured by heating. Next, the photoresist 2 is formed by known vacuum deposition.
A reflective film 15 of aluminum was formed on the surface to a thickness of 500 angstrom (FIG. 25). As described above, a reflective concave blazed grating was obtained.

According to the method of this embodiment, the blazing can be realized by exposing the photoresist with two laser beams having different angles.

[0034]

As described above, according to the invention of claim 1, it is possible to form a grating of an arbitrary pattern on a curved surface with a simple device and without requiring strict environmental management. Become. According to the invention of claim 2 or 3, in addition to the above effects, blazing can be realized.

[Brief description of drawings]

FIG. 1 is a process chart showing the manufacturing method of Example 1. FIG.

2 is a schematic configuration diagram showing a laser drawing apparatus used in Example 1. FIG.

FIG. 3 is a process chart showing the manufacturing method of Example 1.

FIG. 4 is a process chart showing the manufacturing method of Example 1.

FIG. 5 is a process chart showing the manufacturing method of the first embodiment.

FIG. 6 is a process chart showing the manufacturing method of the second embodiment.

FIG. 7 is a process chart showing the manufacturing method of the second embodiment.

FIG. 8 is a process chart showing the manufacturing method of the second embodiment.

FIG. 9 is a process chart showing the manufacturing method of the second embodiment.

FIG. 10 is a process chart showing the manufacturing method of the second embodiment.

FIG. 11 is a process chart showing the manufacturing method of the third embodiment.

FIG. 12 is a process chart showing the manufacturing method of the third embodiment.

FIG. 13 is a process chart showing the manufacturing method of the third embodiment.

FIG. 14 is a process chart showing the manufacturing method of the third embodiment.

FIG. 15 is a process chart showing the manufacturing method of the fourth embodiment.

FIG. 16 is a process chart showing the manufacturing method of the fourth embodiment.

FIG. 17 is a process chart showing the manufacturing method of the fourth embodiment.

FIG. 18 is a process chart showing the manufacturing method of the fourth embodiment.

FIG. 19 is a process chart showing the manufacturing method of the fourth embodiment.

FIG. 20 is a process chart showing the manufacturing method of the fifth embodiment.

FIG. 21 is a process chart showing the manufacturing method of the fifth embodiment.

22 is a perspective view showing a glass substrate used in Example 6. FIG.

FIG. 23 is a process chart showing the manufacturing method of Example 8.

FIG. 24 is a process chart showing the manufacturing method of the eighth embodiment.

FIG. 25 is a process chart showing the manufacturing method of the eighth embodiment.

FIG. 26 is a schematic configuration diagram showing a laser drawing apparatus used in Example 9.

FIG. 27 is a process chart showing the manufacturing method of the ninth embodiment.

FIG. 28 is a process chart showing the manufacturing method of the ninth embodiment.

[Explanation of symbols]

 1 Substrate 2 Photoresist 3,22 Laser drawing device 4 Stage 9 Laser oscillator 10 Autofocus 14 Condensing lens 15 Reflective film 16 Substrate 17 UV curable resin 18 Conductive film 20 Beam splitter

Claims (3)

[Claims] 1. A method of forming unevenness by applying a photosensitizer on a substrate which has been previously processed into a curved surface, exposing the photosensitizer by laser beam drawing, and then developing the exposed photosensitizer. A method for manufacturing a curved grating, characterized by: 2. The method for manufacturing a curved grating according to claim 1, wherein the laser beam is applied from a direction inclined with respect to the center line of the substrate. 3. The method of manufacturing a curved grating according to claim 1, wherein at least two laser beams having mutually different optical axes and having the same converging point are used.