JP2004046003A - Microstructure, method and apparatus for manufacturing microstructure - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a fine structure capable of suppressing a decrease in resolution and forming a good fine shape.
When exposing a photoresist film on a glass master, in a first exposure, a focal position of a laser beam is set to a shallow position near a surface of the photoresist film, and an exposure power is set to a saw. Exposure is performed while modulating the waveform to form a photosensitive region 72 on the surface side of the photoresist film 52. In the second exposure, the focal position of the laser beam 70 is set to a deep position in the photoresist film 52, and exposure is performed while modulating the exposure power in a sawtooth waveform, thereby forming a photosensitive region 74 in the deep portion of the photoresist film 52. . By developing the photoresist film 52 that has been exposed twice, a desired pattern shape is formed on the photoresist film 52.
[Selection diagram] Fig. 4

Description

[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a microstructure such as a diffraction grating, a microlens, a hologram, and a reflector, a microstructure manufactured by applying the manufacturing method, and an apparatus for manufacturing a microstructure.
[0002]
[Prior art]
As a method for processing a fine structure, a photolithography method is known in which a master (eg, a glass master) coated with a photosensitive material is irradiated with laser light, exposed, and developed. For example, Japanese Patent Application Laid-Open No. 2000-292934 discloses that a spot of a laser beam is moved in a radial direction of a master while rotating the master, and a photoresist film on the master is exposed while modulating the intensity of the laser light to perform drawing. A method of doing so is disclosed.
[0003]
[Problems to be solved by the invention]
In the conventional method as described above, for example, when an element having a fine structure such as a diffraction grating or a micro lens is formed, compared with the depth of focus of the spot of the laser beam, when the unevenness of the fine structure is deep, The resolution at the time of exposure is greatly reduced due to defocus. For example, when laser light is focused on the vicinity of the surface of the photoresist film, the reduction in resolution becomes large in the deep part of the photoresist film. For this reason, it has been difficult for the conventional method to form a fine shape of an element such as a diffraction grating satisfactorily (that is, accurately).
[0004]
The present invention has been created by focusing on such a point, and it is an object of the present invention to provide a method of manufacturing a fine structure capable of suppressing a decrease in resolution and forming a good fine shape. I do.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a manufacturing method of the present invention is a method for manufacturing a fine structure in which a photosensitive material film is scanned with a light beam to form an exposure latent image, wherein a first structure in the photosensitive material film is formed. The light beam is intensity-modulated and focused by the first pattern data at the depth position, and the photosensitive material film is scanned by the light beam, and the first exposure latent image is formed on the photosensitive material film by the exposure trajectory. A first exposure latent image forming step of forming, and a light beam at a second depth position in the photosensitive material film is intensity-modulated by the second pattern data and condensed, and the light beam is condensed by the light beam. And a second exposure latent image forming step of forming a second exposure latent image on the photosensitive material film according to the exposure trajectory.
[0006]
In the conventional method, since the exposure latent image corresponding to the desired pattern shape is formed by one exposure, the focal point of the light beam is focused at all the depth positions inside the photosensitive material film (photoresist film). Unable to match, there was a portion where the resolution was reduced. For example, in a shape such as a blazed diffraction grating (a sawtooth-shaped diffraction grating), the roundness of the corners causes a reduction in diffraction efficiency. It was difficult to form both the upper and lower corners sharply.
[0007]
Therefore, in the manufacturing method of the present invention, the focus is set at a plurality of depth positions in the photosensitive material film, and the exposure is performed a plurality of times. As a result, in both the deep part and the vicinity of the surface in the photosensitive material film, it is possible to keep the resolution balance by minimizing the reduction in resolution due to defocus and to form a good shape as a whole. Become. Such a manufacturing method is particularly effective when forming a V-groove shape, a conical shape, a pyramid shape, or a pattern shape having a slope and a vertex (vertex) such as a blazed diffraction grating or a micro Fresnel lens array.
[0008]
Preferably, in the first and second exposure latent image forming steps, the first exposure latent image and the second exposure latent image are combined to form a third exposure latent image.
[0009]
Preferably, the third exposure latent image sets the first depth position at a position shallower than the second depth position, and places the second exposure latent image on the locus of the first exposure latent image. The tracks are superimposed. When a general positive type photoresist film is used as the photosensitive material film, there is a property that the transparency of the exposed portion is increased. For this reason, the light beam should be exposed at a deep position by performing the exposure with the focal point set at a shallow position first, and then performing the exposure with the focus set at a deep position after the transparency of the portion to be exposed increases. This makes it possible to further improve the exposure accuracy.
[0010]
Preferably, the third exposure latent image has a trajectory of the second exposure latent image arranged in a gap between the trajectories of the first exposure latent image. This makes it possible to suppress the irradiation locus (so-called track streak) from appearing in the latent image recorded on the photosensitive material film.
[0011]
Preferably, the first and second pattern data share one exposure profile data.
[0012]
Further, the manufacturing method of the present invention is a method for manufacturing a fine structure in which a photosensitive material film is scanned with a beam light to form an exposure latent image, wherein a first depth position in the photosensitive material film is located at a first depth position. The first light beam is intensity-modulated by the first pattern data and condensed, and the light beam scans the photosensitive material film to form a first exposure latent image on the photosensitive material film based on the exposure trajectory. (1) forming an exposure latent image, and intensifying and condensing a second light beam at a second depth position in the photosensitive material film with second pattern data, and condensing the second light beam with the light beam; And a second exposure latent image forming step of forming a second exposure latent image on the photosensitive material film according to the exposure trajectory.
[0013]
In this way, by setting the focus at a plurality of depth positions in the photosensitive material film and performing exposure with a plurality of light beams, both in the deep part and near the surface in the photosensitive material film, Degradation of resolution due to defocusing can be suppressed as much as possible, and the balance of resolution can be maintained, so that a favorable shape as a whole can be formed. This manufacturing method is also effective particularly when a pattern shape having a slope and an apex (vertex angle) such as a blazed diffraction grating or a similar shape is formed.
[0014]
Preferably, the first and second exposure latent image forming steps described above are performed simultaneously. This makes it possible to collectively perform exposure corresponding to a plurality of depth positions, so that the manufacturing time can be reduced.
[0015]
Preferably, in the first and second exposure latent image forming steps described above, the first exposure latent image and the second exposure latent image are combined to form a third exposure latent image.
[0016]
Preferably, the third exposure latent image has a trajectory of the second exposure latent image superimposed on a trajectory of the first exposure latent image. This makes it possible to further improve the exposure accuracy.
[0017]
Preferably, the third exposure latent image has a trajectory of the second exposure latent image arranged in a gap between the trajectories of the first exposure latent image. This makes it possible to prevent the irradiation trajectory from appearing in the latent image recorded on the photosensitive material film.
[0018]
Preferably, the first and second pattern data share one exposure profile data.
[0019]
Further, the manufacturing method of the present invention is a method in which the beam exposure is condensed on the photosensitive material film applied on the master, and the scanning exposure in which the beam is scanned and irradiated while modulating the amount of light is repeated a plurality of times to obtain a desired beam. An exposure step of recording a pattern on a photosensitive material film, and a developing step of developing the photosensitive material film on which the pattern is recorded and forming a pattern shape having a depth corresponding to the exposure amount, Then, a plurality of focal positions are set at different positions along the depth direction of the photosensitive material film, and exposure corresponding to each of the focal positions is performed by a plurality of scanning exposures.
[0020]
In this manner, by setting a plurality of focal positions in the depth direction of the photosensitive material film and performing a plurality of exposures, the resolution due to the defocusing can be increased both in the deep portion of the photosensitive material film and near the surface. It is possible to keep the resolution balance by minimizing the decrease, and it is possible to form a good shape as a whole. This manufacturing method is also effective particularly when a pattern shape having a slope and an apex (vertex angle) such as a blazed diffraction grating or a similar shape is formed.
[0021]
Preferably, in the exposing step, the exposure in which the focal position of the light beam is set to a shallow position is performed first, and the exposure in which the focal position of the light beam is set to a deep position is performed later. This makes it possible to further improve the exposure accuracy.
[0022]
Preferably, in the exposure step, the exposure is performed by shifting the irradiation position of the light beam on the exposure surface of the master in a direction substantially orthogonal to the scanning direction of the light beam for each of the plurality of scanning exposures. This makes it possible to prevent the irradiation trajectory from appearing in the latent image recorded on the photosensitive material film.
[0023]
Further, in the manufacturing method of the present invention, a plurality of light beams are condensed on a photosensitive material film applied to a master, and scanning exposure is performed in which scanning and irradiation are performed while modulating the light amounts of the plurality of light beams, respectively. An exposure step of recording a desired pattern on the photosensitive material film, and a development step of developing a master on which the pattern is recorded and forming a pattern shape having a depth corresponding to the amount of exposure. In the process, a plurality of focal positions are set at different positions along the depth direction of the photosensitive material film, and exposure corresponding to each of the focal positions is performed by each of the plurality of light beams.
[0024]
In this way, by setting the focus at a plurality of depth positions in the photosensitive material film and performing exposure with a plurality of light beams, both in the deep part and near the surface in the photosensitive material film, Degradation of resolution due to defocusing can be suppressed as much as possible, and the balance of resolution can be maintained, so that a favorable shape as a whole can be formed. This manufacturing method is also effective particularly when a pattern shape having a slope and an apex (vertex angle) such as a blazed diffraction grating or a similar shape is formed.
[0025]
Preferably, in the exposing step, the exposure is performed by mutually shifting the irradiation positions of the plurality of light beams in the exposure surface of the master in a direction substantially orthogonal to the scanning direction of the plurality of light beams. This makes it possible to prevent the irradiation trajectory from appearing in the latent image recorded on the photosensitive material film.
[0026]
Preferably, the thickness of the photosensitive material film and the depth of the pattern shape are made larger than the focal depth of the light beam. This makes it possible to more reliably obtain the effect of suppressing the reduction in resolution due to defocus.
[0027]
The present invention is also a microstructure manufactured using any of the above-described manufacturing methods. More specifically, the microstructure desirably includes at least one of a blazed diffraction grating, a micro Fresnel lens, a hologram, and a reflector. By using the above-described manufacturing method, a fine structure having a favorable fine shape can be obtained.
[0028]
The present invention is also directed to an apparatus for manufacturing a microstructure for forming an exposure latent image by scanning a photosensitive material film with a beam light, comprising: a beam forming means for forming a beam light intensity-modulated by pattern data; Condensing means for condensing light at a desired depth position in the photosensitive material film, and a light beam scanning means for relatively scanning the light beam on the photosensitive material film, comprising: By setting the depth position at the time of condensing the light beam to a plurality of different positions by the light condensing means, and performing the scanning by the light beam a plurality of times corresponding to each depth position by the light beam scanning means. An exposure latent image is formed.
[0029]
Preferably, the pattern data includes first pattern data corresponding to a first depth position and second pattern data corresponding to a second depth position, and using the first pattern data. The scanning corresponding to the first depth position is performed by the intensity-modulated light beam, and then the scanning corresponding to the second depth position is performed by the intensity-modulated light beam using the second pattern.
[0030]
Further, the present invention is an apparatus for manufacturing a fine structure for forming an exposure latent image by scanning a photosensitive material film with a light beam, and forms a first light beam intensity-modulated by first pattern data. A first beam forming unit, a second beam forming unit that forms a second beam light intensity-modulated by the second pattern data, and a first beam forming unit that converts the first and second light beams into first light in the photosensitive material film. And a light beam condensing means for converging light to the second depth position, and a light beam scanning means for relatively scanning the first and second light beams on the photosensitive material film.
[0031]
Preferably, the first and second pattern data share one exposure profile data.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0033]
(1st Embodiment)
FIG. 1 and FIG. 2 are views showing a configuration of a laser writing apparatus (a microstructure manufacturing apparatus) according to the first embodiment. FIG. 1 is a perspective view schematically showing a configuration of a laser drawing apparatus. FIG. 2 is a plan view showing the configuration of the laser drawing apparatus, focusing mainly on the optical system.
[0034]
1 and 2 includes a laser 10, a signal generator 11, an acousto-optic modulator (AOM) 12, two mirrors 14, 16, an objective lens 18, a table 20, a slider 22, and a turntable 24. , And a spindle motor 26.
[0035]
The laser 10 emits laser light (beam light). For example, in the present embodiment, a krypton gas laser having a wavelength λ = 413 nm is used as the laser 10.
[0036]
The signal generator 11 outputs a control signal for controlling the modulation operation of the acousto-optic modulator 12. The acousto-optic modulator 12 modulates the amount of laser light emitted from the laser 10 based on a control signal output from the signal generator 11.
[0037]
The mirror 14 reflects the laser beam emitted from the acousto-optic modulator 12 and guides the laser beam to the mirror 16. The mirror 16 reflects the laser light emitted from the mirror 14 and guides the laser light to the objective lens 18.
[0038]
The objective lens 18 is installed so that the position can be freely adjusted in the vertical direction. The objective lens 18 focuses the laser light emitted from the mirror 16 on a glass master 50 placed on the turntable 24, and Adjust the depth of focus of the. For example, in the present embodiment, the objective lens 18 has a numerical aperture NA (Numerical Aperture) = 0.9.
[0039]
The table (moving optical table) 20 has the acousto-optic modulator 12, mirrors 14, 16 and objective lens 18 mounted thereon, and slowly moves on the slider 22 at a constant speed along the radial direction of the turntable 24. I do.
[0040]
The turntable 24 has the glass master 50 fixed and mounted thereon by vacuum suction, and rotates at a constant speed (for example, 450 rpm) by obtaining the driving force of the spindle motor 26. On the surface of the glass master 50 placed on the turntable 24, a photoresist film 52 is formed. In the present embodiment, a photoresist film 52 having a refractive index n = 1.6 is formed with a thickness of about 5 μm.
[0041]
The laser light emitted from the laser 10, the amount of which is modulated by passing through the acousto-optic modulator 12 is reflected by the two mirrors 14 and 16, and is reflected by the objective lens 18 on the glass master 50 placed on the turntable 24. Is collected. In this embodiment, since the wavelength λ of the laser 10 is 413 nm and the numerical aperture NA of the objective lens 18 is 0.9, the spot diameter of the focal point on the glass master 50 is 1 / e. ² The diameter is 0.82λ / NAμ0.38 μm, and the depth of focus is n · λ / (NA) ² ≒ 0.82 μm. Further, the laser drawing apparatus 100 of the present embodiment can adjust the focal position of the laser beam in the depth direction (thickness direction) of the photoresist film 52 by adjusting the position of the objective lens 18. ing.
[0042]
The photoresist film 52 on the glass master 50 is spirally scanned and exposed by the laser light whose light amount is modulated by the acousto-optic modulator 12, and a pattern corresponding to the light amount of the laser light is recorded as a latent image. At this time, the track pitch is 0.3 μm, which is smaller than the spot diameter, and the entire surface can be exposed by scanning.
[0043]
The laser 10, the signal generator 11, and the acousto-optic modulator 12 are used as beam forming means, the two mirrors 14, 16 and the objective lens 18 are used as condensing means, and the table 20, slider 22, turntable 24 and spindle The motors 26 correspond to the light beam scanning means, respectively.
[0044]
The laser exposure apparatus 100 of the present embodiment has such a configuration. Next, a manufacturing process for manufacturing a fine structure using the laser exposure apparatus 100 will be described in detail. In the following description, a blazed diffraction grating will be described as an example of a microstructure, and a manufacturing method thereof will be described.
[0045]
FIG. 3 is an explanatory diagram illustrating a method for manufacturing a stamper (a thin metal mold) used for manufacturing a microstructure.
[0046]
First, as shown in FIG. 3A, exposure is performed by irradiating the photoresist film 52 on the glass master 50 with laser light whose intensity (exposure power) has been modulated by the acousto-optic modulator 12. Thus, a pattern corresponding to the amount of laser light is recorded on the photoresist film 52 as a latent image. In the present embodiment, a latent image having a pattern corresponding to the shape of the blazed diffraction grating is recorded by performing exposure while modulating the amount of laser light in a sawtooth waveform.
[0047]
Next, as shown in FIG. 3B, the photoresist film 52 on which the latent image of the pattern is recorded is immersed in an alkaline solution together with the glass master 50 and developed. As a result, a part of the photoresist film 52 is removed in accordance with the amount of exposure, and a desired pattern appears on the surface of the photoresist film 52 as an uneven shape.
[0048]
Here, the exposure method for exposing the photoresist film 52 will be described in more detail. FIG. 4 is an explanatory diagram for explaining the exposure method in detail. In the present embodiment, the exposure is performed twice with the focal position of the laser beam set at two positions, a shallow position and a deep position, with respect to the depth direction of the photoresist film 52.
[0049]
Specifically, in the first exposure, as shown in FIG. 4A, the focal position of the laser light 70 is set to a shallow position (see the dotted line A) near the surface of the photoresist film 52, and the first exposure is performed. Exposure is performed while modulating the exposure power in a sawtooth waveform based on the pattern data. As a result, as shown by hatching in FIG. 4A, a photosensitive region (exposure latent image) 72 by the first exposure is formed on the photoresist film 52.
[0050]
In the second exposure, as shown in FIG. 4B, the focal position of the laser light 70 is set to a position deep from the surface of the photoresist film 52 (see the dotted line B), and the exposure is performed based on the second pattern data. Exposure is performed while modulating the power in a sawtooth waveform. As a result, as shown by hatching in FIG. 4B, a photosensitive region 74 is formed in the photoresist film 52 by the second exposure. As described above, in the present embodiment, one exposure profile data is configured by the first and second pattern data, and two exposures are performed based on these pattern data.
[0051]
Thereafter, by developing the photoresist film 52 on which the latent image of the pattern is recorded, a desired pattern can be formed on the photoresist film 52 as shown in FIG.
[0052]
Further, in the above-described exposure method shown in FIG. 4, the exposure power modulation method is the same in the first exposure and the second exposure, but if the exposure power modulation method is different between the first exposure and the second exposure. Exposure may be performed.
[0053]
FIG. 5 is an explanatory diagram for explaining another example of the exposure method in detail. In this case, in the first exposure, as shown in FIG. 5A, the focal position of the laser light 70 is set to a shallow position near the surface of the photoresist film 52 (see the dotted line A), and the exposure power is set. The exposure is performed by modulating so that a trapezoidal waveform including a section of a fixed value and a section that decreases linearly is repeated. As a result, as shown by hatching in FIG. 5A, a photosensitive region 72a is formed in the photoresist film 52 by the first exposure.
[0054]
In the second exposure, as shown in FIG. 5B, the focal position of the laser light 70 is set at a position deep from the surface of the photoresist film 52 (see the dotted line B), and the exposure power decreases linearly. Exposure is performed while modulating so as to repeat a waveform including a section in which power is applied and a section in which power is “0”. As a result, as shown by hatching in FIG. 5B, a photosensitive region 74a is formed in the photoresist film 52 by the second exposure. In this way, by developing the photoresist film 52 on which the latent image of the pattern is recorded, a desired pattern can be formed on the photoresist film 52 as shown in FIG.
[0055]
After performing the exposure and development steps as described above, a conductive film 54 is formed on the surface of the photoresist film 52 by performing electroless plating (NED) as shown in FIG. . For example, in the present embodiment, the conductive film 54 made of nickel is formed.
[0056]
Next, as shown in FIG. 3D, electroforming (electroforming) is performed using the conductive film 54 as an electrode, and nickel is grown in a plate shape on the conductive film 54, so that a stamper (transfer) made of nickel is formed. (Mold) 56 is formed. At this time, by growing nickel so that the plate thickness becomes about 300 μm, it is possible to form the stamper 56 having sufficient mechanical strength.
[0057]
Thereafter, as shown in FIG. 3E, the stamper 56 is peeled from the glass master 50 to complete the stamper 56 on which the fine pattern formed on the surface of the photoresist film 52 is transferred.
[0058]
Next, a method of manufacturing a blazed diffraction grating as a fine structure using the stamper 56 manufactured by the above-described method will be described.
[0059]
FIG. 6 is an explanatory diagram illustrating a method for manufacturing a microstructure (blazed diffraction grating in this example). First, as shown in FIG. 6A, a UV curable resin is applied to a thickness of about 10 μm on a glass substrate 60 to form a resin layer 62. Next, as shown in FIG. 6B, the pattern forming surface of the stamper 56 is pressed toward the resin layer 62. Thereafter, as shown in FIG. 6C, the resin layer 62 is irradiated with ultraviolet rays (UV) from the rear surface side of the glass substrate 60 while the stamper 56 is pressed, so that the resin layer 62 is cured.
[0060]
Next, the stamper 56 is peeled from the cured resin layer 62. Thereby, as shown in FIG. 6D, a blazed diffraction grating 64 configured by laminating a resin layer 62 on which a sawtooth-shaped fine unevenness pattern (mushroom shape) is transferred on a glass substrate 60. Is formed.
[0061]
As described above, in the manufacturing method according to the first embodiment, the focus is set at two depth positions in the photoresist film, and the exposure is performed twice corresponding to each focus. In both the deep part of the film and the vicinity of the surface, it is possible to keep the resolution balance by minimizing the reduction in resolution due to defocusing, and to form a good shape as a whole. By manufacturing a blazed diffraction grating by the manufacturing method of the present embodiment, it is possible to form an edge portion (vertical angle portion) of a sawtooth waveform at an acute angle, and to obtain a blazed diffraction grating having high diffraction efficiency. It becomes.
[0062]
By the way, in the above description, in the first exposure in which the focal position is set to a shallow position and in the second exposure in which the focal position is set to a deep position, the same position in the radial direction of the glass master 50 is irradiated with laser light. However, it is more preferable to perform the exposure while shifting the irradiation position of the laser beam in the radial direction of the glass master 50 (that is, the direction substantially orthogonal to the scanning direction of the laser beam) according to the focal position. In other words, the method of shifting the irradiation position of the laser beam can be expressed as disposing the trajectory of the exposure latent image by the second exposure in the gap between the trajectories of the exposure latent image by the first exposure.
[0063]
FIG. 7 is an explanatory diagram for explaining an exposure method in the case where exposure is performed by shifting the irradiation position in the radial direction of the glass master according to the focal position. FIG. 7A is a perspective view schematically illustrating a cross section of a part of the photoresist film 52, and FIG. 7B is a diagram illustrating a surface of the photoresist film 52 orthogonal to the traveling direction of the laser light 70. This is shown in a sectional view.
[0064]
In FIG. 7A, arrows A1 and A2 indicate the irradiation direction of the laser light 70 in the first exposure performed by setting the focal position to a shallow position. Arrows B1 and B2 indicate the irradiation direction of the laser beam 70 in the second exposure performed by setting the focal position to a deep position. FIG. 7B shows the arrows A1, A2, B1, and B2 viewed from behind. In this manner, the exposure is performed by shifting the irradiation position at the time of the first and second exposures so that the exposure latent image by the first exposure and the exposure latent image by the second exposure partially overlap. Accordingly, it is possible to suppress the irradiation locus (so-called track streak) from appearing in the latent image recorded on the photoresist film 52.
[0065]
(Second embodiment)
FIG. 8 and FIG. 9 are diagrams illustrating the configuration of the laser writing apparatus according to the second embodiment. FIG. 8 is a perspective view schematically showing the configuration of the laser drawing apparatus. FIG. 9 is a plan view showing the configuration of the laser drawing apparatus, focusing mainly on the optical system.
[0066]
The laser writing apparatus 100a according to the second embodiment shown in FIGS. 8 and 9 has basically the same configuration as the laser writing apparatus 100 according to the first embodiment described above. 8 and 9, the same components as those of the laser writing apparatus 100 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0067]
The laser drawing apparatus 100a includes a laser 10, a signal generator 11a, two acousto-optic modulators (AOMs) 12a and 12b, a beam splitter 13, three mirrors 14a, 14b and 16, a focal position adjusting lens 15a and 1/2. The optical unit 15 includes a wavelength plate 15b, a polarizing beam splitter 17, an objective lens 18, a table 20, a slider 22, a turntable 24, and a spindle motor 26.
[0068]
The signal generator 11a outputs a control signal for controlling the modulation operation of each of the two acousto-optic modulators 12a and 12b.
[0069]
The acousto-optic modulator 12a modulates the amount of laser light emitted from the laser 10, passing through the beam splitter 13, and entering based on a control signal output from the signal generator 11a.
[0070]
The acousto-optic modulator 12b modulates the amount of laser light emitted from the laser 10, passing through the beam splitter 13 and the mirror 14b, and entering based on the control signal output from the signal generator 11a.
[0071]
The beam splitter 13 splits the laser beam emitted from the laser 10 into two beams, and passes one of the laser beams (hereinafter, referred to as “laser beam L1”) without changing the traveling direction. The laser beam (hereinafter, referred to as “laser beam L2”) has its traveling direction changed by approximately 90 degrees.
[0072]
The mirror 14a reflects the laser beam L1 emitted from the acousto-optic modulator 12a and guides the laser beam L1 to the polarization beam splitter 17. The mirror 14b reflects the laser beam L2 emitted from the beam splitter 13 and guides the laser beam L2 to the acousto-optic modulator 12b.
[0073]
The focal position adjusting lens 15a adjusts the focal position of the laser light emitted from the acousto-optic modulator 12b, and emits the laser light as light that slightly diffuses. The half-wave plate 15b rotates the polarization plane of the laser light emitted from the focal position adjusting lens 15a.
[0074]
The polarization beam splitter 17 combines the laser light emitted from the mirror 14a and the laser light incident from the half-wave plate 17b, and emits the combined light toward the mirror 16. The mirror 16 reflects the laser light emitted from the polarization beam splitter 17 and guides the laser light to the objective lens 18.
[0075]
The objective lens 18 condenses the laser light emitted from the mirror 16 on a glass master 50 placed on the turntable 24. At this time, since one laser beam L2 that has passed through the focus adjusting lens 15a is slightly diffused light, the focal positions of the laser beams L1 and L2 focused on the glass master 50 are shifted from each other. be able to. The focal position can be adjusted by changing the curvature of the focus adjusting lens 15a.
[0076]
The laser 10, the signal generator 11a, the acousto-optic modulator 12a, and the beam splitter 13 serve as the first beam forming means, and the laser 10, the signal generator 11a, the acousto-optic modulator 12b, the beam splitter 13, and the mirror 14b. Are the second beam forming means, the mirrors 14a and 16, the focal position adjusting lens 15a, the half-wave plate 15b, the polarizing beam splitter 17 and the objective lens 18 are the condensing means, the table 20, the slider 22, and the turntable 24. And the spindle motor 26 correspond to the light beam scanning means.
[0077]
The laser writing apparatus 100a of the second embodiment has such a configuration. Next, a description will be given of a manufacturing process when manufacturing a microstructure using the laser writing apparatus 100a.
[0078]
In the laser drawing apparatus 100a, since the focal positions of the laser beams L1 and L2 can be adjusted independently of each other, for example, the focal position of the laser beam L1 is set to a position shallow with respect to the depth direction of the photoresist film 52. 4 (a) or 5 (a), the focal position of the laser beam L2 is set to a position deeper in the depth direction of the photoresist film 52 (FIG. 4 (b) or 5 (b). )), Two exposures can be performed almost simultaneously. This makes it possible to significantly reduce the time required for exposure.
[0079]
In the second embodiment, it is also possible to perform the exposure by shifting the irradiation position of the laser beam at the time of the first and second exposures according to the focal position. In this case, the arrangement of the optical system of the laser drawing apparatus 100a is changed so that the irradiation positions of the laser light L1 and the laser light L2 on the glass master 50 are shifted in the radial direction of the glass master 50 to condense the light. What should I do?
[0080]
(Modifications, etc.)
The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention. For example, in each of the above-described embodiments, a method of manufacturing a blazed diffraction grating, which is one of the microstructures, has been described. However, the scope of the present invention is not limited to this, and is illustrated in FIG. The present invention can also be applied to the case of manufacturing such a micro Fresnel lens, or a hologram, a reflector, or other various fine structures having a fine shape such as a V-groove shape, a conical shape, or a pyramid shape.
[0081]
Further, in the above-described first embodiment, the focus position is set at two positions, that is, a shallow position and a deep position, and the exposure is performed twice. However, the focus position is set at two or more positions and a plurality of positions are set. The exposure may be performed twice. Similarly, in the second embodiment, the focus position is set at two positions, that is, a shallow position and a deep position, and exposure is performed using two laser beams. However, the focus position is set at two or more positions. Exposure with two or more laser beams may be performed. Also, the method of modulating the exposure power at the time of exposure is not limited to the method described in the above embodiment, and can be appropriately set according to the shape of the microstructure to be formed.
[0082]
Further, in each of the embodiments described above, the laser irradiation position is moved in the radial direction of the glass master while the glass master is rotated, and the exposure is performed. However, the glass master is fixed and the laser irradiation position is two-dimensionally adjusted. The present invention can be applied to a case where a so-called XY table type laser drawing apparatus that performs exposure while moving the object is used.
[0083]
【The invention's effect】
As described above, according to the present invention, a plurality of depth positions are set in the photosensitive material film, and the exposure is performed a plurality of times. In addition, it is possible to keep the balance of the resolution while minimizing the reduction of the resolution due to the defocus, and to form a good shape as a whole.
[0084]
Further, according to the present invention, since a plurality of depth positions are set in the photosensitive material film and exposure is performed by a plurality of light beams, the focal point can be set in any of the deep portion and the vicinity of the surface in the photosensitive material film. It is possible to maintain the balance of resolution while minimizing the reduction in resolution due to blurring, and to form a good shape as a whole.
[0085]
Such a manufacturing method is particularly effective when a V-groove shape, a conical shape, a pyramid shape, or a pattern shape having a slope and an apex (vertex), such as a blazed diffraction grating or a micro Fresnel lens array, is accurately formed. It is possible to provide a fine structure having a good fine shape.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a laser writing apparatus according to a first embodiment.
FIG. 2 is a diagram illustrating a configuration of a laser writing apparatus according to the first embodiment.
FIG. 3 is an explanatory diagram illustrating a method of manufacturing a stamper used for manufacturing a microstructure.
FIG. 4 is an explanatory diagram for explaining an exposure method in detail;
FIG. 5 is an explanatory diagram for explaining another example of the exposure method in detail.
FIG. 6 is an explanatory diagram illustrating a method for manufacturing a fine structure.
FIG. 7 is an explanatory diagram illustrating an exposure method when performing exposure while shifting the irradiation position in the radial direction of the glass master according to the focal position.
FIG. 8 is a diagram illustrating a configuration of a laser writing apparatus according to a second embodiment.
FIG. 9 is a diagram illustrating a configuration of a laser writing apparatus according to a second embodiment.
FIG. 10 is a diagram illustrating an example of a micro Fresnel lens.
[Explanation of symbols]
10 Laser
11 signal generator
12 Acoustic-optic modulator (AOM)
14, 16 mirror
18 Objective lens
20 tables
22 Slider
24 Turntable
26 Spindle motor
50 glass master
52 Photoresist film
54 conductive film
56 Stamper
60 glass substrate
62 resin layer
64 blazed diffraction grating

Claims (23)

A method for manufacturing a fine structure for forming an exposure latent image by scanning a photosensitive material film with a beam light,
The light beam is intensity-modulated and condensed at a first depth position in the photosensitive material film by first pattern data, and the light beam is scanned on the photosensitive material film to scan the photosensitive material film according to the exposure locus. A first exposure latent image forming step of forming a first exposure latent image on the photosensitive material film;
The light beam is intensity-modulated by a second pattern data and condensed at a second depth position in the photosensitive material film, the light beam is scanned on the photosensitive material film, and the exposure locus is used. A second exposure latent image forming step of forming a second exposure latent image on the photosensitive material film;
A method for producing a microstructure, comprising: 2. The method according to claim 1, wherein the first and second exposure latent images are formed by combining the first and second exposure latent images in the first and second exposure latent image forming steps. 3. A method for manufacturing a microstructure. The third exposure latent image sets the first depth position at a position shallower than the second depth position, and places the second exposure latent image on a locus of the first exposure latent image. The method for manufacturing a microstructure according to claim 2, wherein the trajectories of the images are superimposed. 3. The method according to claim 2, wherein the third exposure latent image has a trajectory of the second exposure latent image arranged in a gap between trajectories of the first exposure latent image. 4. 4. The method according to claim 3, wherein the first and second pattern data share one exposure profile data. 5. A method for manufacturing a fine structure for forming an exposure latent image by scanning a photosensitive material film with a beam light,
A first light beam is intensity-modulated and condensed by first pattern data at a first depth position in the photosensitive material film, and the photosensitive material film is scanned by the light beam to expose the light beam. A first exposure latent image forming step of forming a first exposure latent image on the photosensitive material film by
A second light beam is intensity-modulated by a second pattern data and condensed at a second depth position in the photosensitive material film, and the photosensitive material film is scanned with the light beam to expose the light beam. A second exposure latent image forming step of forming a second exposure latent image on the photosensitive material film by
A method for producing a microstructure, comprising: The method for manufacturing a microstructure according to claim 6, wherein the first and second exposure latent image forming steps are performed simultaneously. 9. The method according to claim 7, wherein the first and second exposure latent images are combined to form a third exposure latent image by the first and second exposure latent image forming steps. 9. A method for producing the microstructure according to the above. The method for manufacturing a microstructure according to claim 8, wherein the third exposure latent image has a trajectory of the second exposure latent image superimposed on a trajectory of the first exposure latent image. 9. The method of manufacturing a microstructure according to claim 8, wherein the third exposure latent image has a trajectory of the second exposure latent image arranged in a gap between trajectories of the first exposure latent image. 10. The method according to claim 9, wherein the first and second pattern data share one exposure profile data. Focusing the beam light on the photosensitive material film coated on the master, scanning the beam light while modulating the light amount and repeating the scanning exposure for irradiation a plurality of times to form a desired pattern on the photosensitive material film An exposure step for recording;
Developing the photosensitive material film on which the pattern is recorded, and a developing step of forming a pattern shape having a depth corresponding to the exposure amount,
The exposing step sets a plurality of focal positions at different positions along the depth direction of the photosensitive material film, and performs exposure corresponding to each of the focal positions by the scanning exposure a plurality of times, the fine structure How to make the body. 13. The microstructure according to claim 12, wherein the exposing step performs exposure in which the focal position of the light beam is set to a shallow position first, and performs exposure after setting the focal position of the light beam to a deep position. Production method. The exposure step, for each of a plurality of times of the scanning exposure, performing exposure by shifting the irradiation position of the light beam in the exposure surface of the master in a direction substantially orthogonal to the scanning direction of the light beam, A method for producing a microstructure according to claim 12. A plurality of light beams are condensed on the photosensitive material film applied to the master, and scanning exposure is performed by scanning and irradiating while modulating the light amounts of the plurality of light beams, thereby forming a desired pattern on the photosensitive material. An exposure step of recording on the film;
Developing the master on which the pattern is recorded, and a developing step of forming a pattern shape having a depth corresponding to the exposure amount,
The exposing step sets a plurality of focal positions at different positions along the depth direction of the photosensitive material film, and performs exposure corresponding to each of the focal positions by each of the plurality of light beams. The method of manufacturing the structure. 16. The exposure according to claim 15, wherein, in the exposing step, the irradiation positions of the plurality of light beams on the exposure surface of the master are mutually shifted in a direction substantially orthogonal to a scanning direction of the plurality of light beams, and the exposure is performed. A method for manufacturing a microstructure. 17. The method according to claim 12, wherein a thickness of the photosensitive material film and a depth of the pattern shape are larger than a focal depth of the light beam. A microstructure manufactured by the manufacturing method according to claim 1. The microstructure according to claim 18, wherein the microstructure includes at least one of a blazed diffraction grating, a micro Fresnel lens, a hologram, and a reflector. An apparatus for manufacturing a fine structure that scans a photosensitive material film with a light beam to form an exposure latent image,
Beam forming means for forming a light beam intensity-modulated by pattern data, and a light condensing means for condensing the light beam at a desired depth position in the photosensitive material film,
Light beam scanning means for relatively scanning the light beam on the photosensitive material film,
The depth position when condensing the light beam by the light condensing means is set to a plurality of different positions, and the light beam scanning means scans the light beam a plurality of times corresponding to each depth position. An apparatus for manufacturing a microstructure, wherein the apparatus forms the exposure latent image by performing the method. The pattern data includes first pattern data corresponding to a first depth position and second pattern data corresponding to a second depth position,
A scan corresponding to the first depth position is performed by the light beam intensity-modulated using the first pattern data, and then the second depth is scanned by the light beam intensity-modulated using the second pattern. 21. The apparatus for manufacturing a microstructure according to claim 20, wherein scanning corresponding to the position is performed. An apparatus for manufacturing a fine structure that scans a photosensitive material film with a light beam to form an exposure latent image,
First beam forming means for forming a first light beam intensity-modulated by the first pattern data;
Second beam forming means for forming a second light beam intensity-modulated by the second pattern data;
Focusing means for focusing the first and second light beams at first and second depth positions in the photosensitive material film, respectively;
Light beam scanning means for relatively scanning the first and second light beams on the photosensitive material film;
A manufacturing apparatus for a microstructure including: 23. The microstructure manufacturing apparatus according to claim 21, wherein the first and second pattern data share one exposure profile data.

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