KR20070095362A - Exposure method, method for forming projecting and recessed pattern, and method for manufacturing optical element - Google Patents

Abstract

An exposure pattern having a line width of submicron size is simply formed by using an inexpensive and stable solid state laser or a gas laser as an exposure light source, and by using a photoresist for g-line or i-line. The exposure is performed by locally controlling a reaction time constant of the photosensitive material with beaming the laser beam on a predetermined portion of a layer of the photosensitive material having a predetermined thickness formed on the surface of a substrate W, with beam intensity and scanning rate of the laser beam being controlled.

Description

Exposure method, formation method of uneven | corrugated pattern, and manufacturing method of an optical element {EXPOSURE METHOD, METHOD FOR FORMING PROJECTING AND RECESSED PATTERN, AND METHOD FOR MANUFACTURING OPTICAL ELEMENT}

Field of technology

TECHNICAL FIELD The present invention relates to an exposure method, a method of forming an uneven pattern, and a method of manufacturing an optical element, and more particularly, an optical having an uneven pattern used in an application such as an antireflection film having an uneven pattern and another member. An exposure method suitable for manufacturing an element, a method of forming an uneven pattern using the exposure method, and a method of manufacturing an optical element.

Background

Conventionally, photofabrication using photosensitive photoresist has been applied to various fields. For example, the technical field requiring relatively low precision includes application to printed boards, and the technical field requiring relatively high precision includes application to semi-structures such as LSI.

As light sources (beam sources) used for photofabrication, charged particle beams such as mercury lamps, laser beams, and electron beams have been used. As the patterning method, a mask exposure method in which an exposure pattern is formed using a mask pattern such as a photomask, and a direct drawing method in which a beam is scanned in a pattern shape so that the exposure pattern is formed have also been used.

Among the pattern methods, the direct drawing method performed using the laser beam has a high degree of freedom in patterning, and is suitable for the form of manufacturing many kinds in a small amount. For this reason, the direct drawing method is applied to the production of a photomask (forming an exposure pattern) for forming a semiconductor circuit or the like (see, for example, Japanese Patent Laid-Open No. 2004-144885).

Japanese Patent Application Laid-Open No. 2004-144885 proposes a laser beam in which exposure processing on a unit pattern is repeated to form a plurality of units, and a plurality of laser beams are used and elements causing dimensional variations in each beam are corrected. The method relates to the correction.

In recent years, there has been a strong demand for making the line width of semiconductor circuits very thin with the miniaturization of design rules of semiconductor circuits. In order to cope with these demands, there has also been a strong demand for making the beam width of the laser beam very thin.

However, the beam width of the laser beam corresponds to the Airy disk of the laser beam and, therefore, can only converge at a level equivalent to the wavelength length of the laser light source because of the diffraction limit. 7 is a conceptual diagram illustrating this phenomenon.

The laser beam having a beam diameter of 2n is focused by the lens 2, but the spot size is limited to the primary airy disk 3 by diffraction. However, the spot size for photoresist exposure extends to the secondary airy disk 4. Therefore, in this situation, the requirements for reducing the line width to 1 μm or less cannot be satisfied using ordinary laser light sources (semiconductor lasers, CO ₂ gas lasers, YAG lasers, etc.).

On the other hand, in the formation of the submicron pattern, drawing is performed using an ArF laser, an ultraviolet laser light source such as KrF laser, and a charged particle beam such as an electron beam. However, UV laser light sources are expensive and difficult to maintain to maintain their stability, and also have the disadvantage that extremely expensive resists must be used.

In addition, the electron beam exposure device has the disadvantage that the need for a vacuum chamber, an electron beam gun, an electron beam deflector, etc. makes the device complicated and expensive, and also has a small drawing area and a slow drawing speed. Has

Alternatively, special methods have been proposed, such as a method of suppressing the diffusion of the beam by filling a special liquid between the focus lens and the photoresist so that exposure is performed, and a method of forming a microstructure using near field light. . However, these special methods are not simple and do not make it possible to form microstructures simply and inexpensively.

The present invention is made in view of the above-described environment. An object of the present invention is to use a stable and inexpensive solid state laser (YAG laser, etc.) and a gas laser (Ar ⁺ laser, etc.) as an exposure light source, and to use a conventionally used g-line or i-line photoresist. The exposure method which makes it possible to simply form the exposure pattern whose line width is submicron size, and also provides it using the exposure method, the method of forming an uneven | corrugated pattern, and the method of manufacturing an optical element.

Disclosure of the Invention

According to the present invention, in order to achieve the above object, while controlling the beam intensity and the beam scanning speed of the laser beam, the reaction time constant of the photosensitive material having a predetermined thickness formed on the substrate surface is applied to the layer of the photosensitive material. It is characterized in that the exposure is performed to be locally controlled by irradiation.

According to the invention, exposure is performed to locally adjust the reaction time constant of the photosensitive material by irradiating the laser beam to the layer of photosensitive material while controlling the beam intensity and the beam scanning speed of the laser beam, as a result of which the exposure beam It is possible to perform drawing with a line width that is thinner than the Airy disk of. Thereby, as an exposure light source, a submicron size is used using a low-cost and stable solid-state laser (YAG laser, etc.) and a gas laser (Ar ⁺ laser, etc.) and conventionally used g-line or i-line photoresist. It is possible to easily form an exposure pattern having a line width.

That is, according to the present invention, there is provided a method of forming an exposure pattern having a line width of submicron size by using a nonlinear characteristic of a transient reaction state and not normally in a normal state when exposing a photosensitive material such as a photoresist. . The detailed principle of the method will be described later. Further, according to the present invention, by controlling the beam intensity and the pulse width of the laser beam, the reaction time constant of the photoresist material having a predetermined thickness formed on the surface of the substrate is irradiated with the laser beam in the pulse state to the layer of the photosensitive material. An exposure method is provided, characterized in that exposure is performed while being controlled locally.

According to the invention, exposure is performed to locally control the reaction time constant of the photosensitive material by irradiating the laser beam in a pulsed state to the layer of the photosensitive material while controlling the beam intensity and the pulse width of the laser beam. It is possible to perform drawing of posts and / or holes of smaller size than the airy disk of the exposure beam. Thereby, a submicron size using an inexpensive and stable solid-state laser (YAG laser, etc.) and gas laser (Ar ⁺ laser, etc.) as the exposure light source, and conventionally used g-line or i-line photoresist It is possible to simply form an exposure pattern having a post width and / or a hole, or a line width of a submicron size.

In the present invention, it is preferable that the above-described laser beam is interference light in space and time. If the beam is interfering light in space and time, more advantages according to the invention can be obtained.

According to the present invention, there is also provided a method, comprising: forming a layer of photosensitive material having a predetermined thickness on a surface of a substrate; Performing exposure to locally control the reaction time constant of the photosensitive material by controlling the beam intensity and the beam scanning speed of the laser beam while applying the laser beam to the layer of photosensitive material; A method of forming an uneven pattern is provided by applying developing processing to a layer of photosensitive material after exposure to form a plurality of fine uneven patterns in the layer of photosensitive material.

According to the present invention, the above-described exposure method is applied to form the uneven pattern so that the uneven pattern having high precision can be manufactured inexpensively and stably.

In the present invention, the height of the uneven pattern is preferably set to 0.1 to 100 µm. When the height of the concave-convex pattern is set in this range, desired optical properties such as an antireflection function can be preferably made, and an advantage can also be obtained in terms of production.

In the present invention, the substrate is preferably a columnar body or a cylinder. In the case where the substrate is a columnar or cylindrical body, as will be described later, roll processing can be employed when a substrate having an uneven pattern is used to further duplicate an optical element having an uneven pattern, and the like, and as a result, productivity is considerably increased. It can be improved, and many advantages can be obtained in terms of cost reduction and the like.

In addition, according to the present invention, there is provided a method for manufacturing an optical element using the above-described method for forming the uneven pattern, a stamper for transferring a plurality of uneven patterns by using a plurality of uneven patterns formed on the surface of the substrate Preparing a; And duplicating a plurality of uneven patterns substantially the same in shape as the plurality of uneven patterns by molding using a stamper.

According to the invention, the optical element can be further duplicated using a substrate already prepared. That is, a stamper is manufactured and a some fine uneven | corrugated pattern is formed on the surface of a resin material by shape | molding using a stamper. As a result, productivity can be significantly improved, and many advantages can also be obtained in terms of cost reduction and the like.

The stamper generally indicates a planar body on which the surface shape of the substrate (mother) is transferred, but here having a curved surface such as a columnar body or a cylinder body may also be used as the stamper.

As described above, according to the exposure method of the present invention, it is possible to perform drawing with holes and / or posts or line widths thinner than the airy disk of the exposure beam.

In addition, according to the method for forming the uneven pattern of the present invention, the above-described exposure method is applied to form the uneven pattern so that the uneven pattern having high precision can be manufactured at low cost and stably.

In addition, according to the method for manufacturing the optical element of the present invention, a stamper is manufactured and a plurality of fine uneven patterns are formed on the surface of the resin material by molding using the stamper. By this, productivity can be considerably improved, and many advantages can also be obtained in terms of cost reduction and the like.

Brief description of the drawings

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the exposure device used for the exposure method which concerns on this invention, the method of forming an uneven | corrugated pattern, and the method of manufacturing an optical element.

2 is a conceptual diagram illustrating a mode in which the surface of the substrate is drawn by the focused laser beam.

3 is a graph showing the absorbance characteristics of the photoresist at each wavelength.

4 is a conceptual diagram illustrating an energy diagram of a photoresist.

5A is a schematic cross-sectional view illustrating the step of processing a substrate.

5B is a schematic cross-sectional view illustrating the step of processing a substrate.

5C is a schematic cross-sectional view illustrating the step of processing a substrate.

6A is a conceptual diagram illustrating a step of manufacturing a stamper.

6B is a conceptual diagram illustrating a step of manufacturing a stamper.

6C is a conceptual diagram illustrating a step of manufacturing a stamper.

6D is a conceptual diagram illustrating a step of manufacturing a stamper.

7 is a conceptual diagram illustrating a profile of a laser beam.

8A is a conceptual diagram illustrating another step of manufacturing a stamper.

8B is a conceptual diagram illustrating another step of manufacturing a stamper.

8C is a conceptual diagram illustrating another step of manufacturing a stamper.

8D is a conceptual diagram illustrating another step of manufacturing a stamper.

8E is a conceptual diagram illustrating another step of manufacturing a stamper.

Explanation of the sign

10: exposure device

12: exposure light source

14: substrate table

16: laser light source

18: collimator lens

20: base

22: X axis movement stage

24: Y axis moving stage

30: photoresist layer

40: conductive layer

42: nickel layer (reversed mother)

44: nickel layer (Ni mother)

46: nickel layer (stamper)

W: Sample (substrate)

example To practice the invention  Best form for

Next, according to this invention, preferable embodiment of the exposure method, the method of forming an uneven | corrugated pattern, and the method of manufacturing an optical element is demonstrated with reference to an accompanying drawing. 1 shows an outline of an exposure device used in the exposure method, the uneven pattern forming method, and the optical element manufacturing method according to the present invention.

The exposure device 10 of FIG. 1 includes an exposure light source 12 and a substrate table 14, which includes a laser light source 16 and a collimator lens 18. The laser beam L, which is parallel light having a light beam of a predetermined diameter emitted from the laser light source 16, is collected by the collimator lens 18 and can be adjusted to be irradiated to the surface of the substrate W at a focal length.

The substrate table 14 includes a base 20, an X axis moving stage 22, a Y axis moving stage 24, and the like. The X axis moving stage 22 can be relatively moved in the X axis direction as shown in FIG. 1 by a drive device (not shown). In addition, the Y-axis moving stage 24 can be moved relative to the X-axis moving stage 22 in the Y-axis direction by the driving device (not shown).

On the upper surface of the Y axis moving stage 24, a chuck (eg, a static chuck (not shown)) is provided for adsorbing the substrate W so that the substrate W can be fixed.

The photosensitive material (photoresist) formed on the surface of the substrate W is exposed by the exposure device 10 configured as described above. FIG. 2 is a conceptual diagram (plan view) showing a mode in which the surface of the substrate W is drawn by the focused laser beam. In Fig. 2, the spot P of the laser beam at the focal position of the collimator lens 18 is scanned in the X-axis direction and the Y-axis direction as shown by the dotted line in the figure, and almost the entire surface of the substrate W The X-axis movement stage 22 and the Y-axis movement stage 24 are driven so that this exposure may be performed.

As the laser light source 16, an Nd: YAG laser can be used. The wavelength of the second harmonic SHG of the laser light source 16 is 532 nm. As the laser light source 16, an argon laser can be used in addition to the YAG laser. Other types of laser light sources may be used as long as the beam 16 as the laser light source is interfering light in space and time. In addition, when a stable laser light source having a short wavelength is obtained, the laser light source is preferably used.

The number of longitudinal modes of the exposure beam emitted from the laser light source 16 is preferably 3 or less. This is because the spontaneous transition probability to be described later depends on the number of vertical modes. Ideally, laser light in which the exposure beam has a number of longitudinal modes of one (single longitudinal mode) is preferably used.

As the substrate W, plate glass, a silicon wafer, a ceramic substrate, or the like can be used. On the surface of the substrate W, a photoresist layer is formed as a photosensitive material. As the photoresist, various kinds of known materials can be used. When a YAG laser or an argon ion laser is used as the laser light source 16, conventionally used photoresist for g-line or i-line can be preferably used.

As such photoresist, for example, Arch Corp. photoresist (product name: OIR-907) can be used. As a method of forming a photoresist layer on the surface of the substrate W, various kinds of coating methods including, for example, spin-coating method, dye coating method, roll coating method, dip coating method, screen printing method and the like; There are various kinds of known methods.

Next, the principle of the exposure method according to the present invention will be described. In the present invention, the laser beam is controlled from the laser light source 16 to the layer of photoresist while the beam intensity is controlled and the moving speed (scan speed) in the X-axis direction and the Y-axis direction of the substrate table 14 is controlled. Is investigated.

That is, exposure is performed to locally adjust the reaction time constant of the photoresist. This makes it possible to perform drawing with a line width thinner than the Airy disc of the exposure beam. That is, upon exposure of the photoresist, an exposure pattern having a line width of submicron size is formed using nonlinear characteristics in a transient response state rather than a normal steady state.

In this case, the following combination is used as the characteristics of the photoresist and the laser light source 16 described above. 3 is a graph showing the absorbance (Abs.) Characteristics of the photoresist at each wavelength (λ).

In Fig. 3, a laser light source characterized by a high wavelength (for example, [lambda] 1) having a high absorbance Abs. Of the photoresist is generally used. However, in the present invention, a laser light source characterized by a wavelength (for example, [lambda] 2) having a low absorbance Abs. Of the photoresist is used.

That is, the laser light source characterized by the wavelength included in the resonance region indicated by arrow R1 of FIG. 3 having a high absorbance Abs. Of the photoresist is not used, and the absorbance Abs. Of the photoresist is low. A laser light source is used which is characterized by the wavelength contained in the non-resonant region indicated by.

In this regard, as a result of extensive investigation, the present inventors have a condition that the absorption cross-sectional area of the photosensitive material (photoresist, etc.) is large in the excited state of the photoreaction, and that the induced transition probability from the excited state is large and the spontaneous transition probability is small. Below, it was found that the reaction time constant τ of the photosensitive material (photoresist, etc.) was in the form of τ (I) which largely depends on the number of photons, that is, the intensity I and the frequency of light incident on the photosensitive material.

4 is a conceptual diagram illustrating an energy diagram of a photoresist. In Fig. 4, Φ _A is a spontaneous transition probability, Φ _B is an induction transition probability, K is a thermal velocity constant, σ is an absorption (induction) cross section.

In the energy diagram shown in FIG. 4, the number of atoms in each level is defined as N (1), N (2), and N (3), respectively. In the present invention, a general reaction system in which energy transfer is caused through an energy level of level 3 is considered. In the present invention, due to the use of the interference interaction of the photoresist, the thermal mode reaction is regarded as sufficiently small compared to the photon mode reaction, and the exposure when scanning the exposure beam instead of the reaction after sufficient time has elapsed. Since the phenomenon is used, the ratio equation in the transient response area of the photoresist is taken into account.

In the energy diagram, the lifetime of level 2 is sufficiently short compared to the lifetime of level 3, and consequently, the time change of N (3) is very slow compared to the time change of N (2). The reaction time constant of the photoresist energy-transferred from level 3 is judged to be very different from the reaction time constant in the photon mode described above, so that only the photon mode reaction is considered to contribute to the time change of N (3).

Then, the inventors found that in the exposure method according to the present invention, each of the above-described parameters can be controlled so that the reaction rate of the photosensitive material can be intentionally handled by controlling the beam intensity and the irradiation time of the exposure beam. The irradiation time of the exposure beam is controlled based on the adjustment of the scanning speed of the substrate W.

Then, by solving the ratio equation in the transient response time based on the energy diagram of the photoresist shown in FIG. 4, the inventors have shown that the reaction time constant τ is represented by the formula (1), and ω is the frequency of the light source. Where I is the intensity of the irradiation light and ħ is the Dirac constant.

Here, the equation of τ = τ (0) represents the time delay from when light of sufficiently low intensity is incident on the photosensitive material (photoresist, etc.) to the start of the photochemical reaction in the photosensitive material.

Further, τ (I) indicates that the time delay from when light falls on the photosensitive material to when the photochemical reaction starts on the photosensitive material is a nonlinear constant according to the light intensity. The reaction time constant of the photosensitive material (photoresist, etc.) is constant during exposure by using ordinary interference light.

As a specific method, for example, under the control of the irradiation time of the exposure beam, the reaction time constant τ (I: large) of the photoresist is reduced in the region where the incident light intensity I is high, so that the reaction proceeds at a high rate, and the incident light In the region where the intensity I is low, the reaction time constant τ (I: small) of the photoresist is increased, so that the reaction proceeds at a low rate. Thereby, the photochemical reaction can be suppressed in the region of low intensity within the light intensity distribution of the exposure beam, and as a result, it is possible to perform drawing with a line width thinner than that of the airy disk of the exposure beam.

This makes it possible to simply form an exposure pattern having a line width of submicron size by using an inexpensive and simple device, and as a result, various fine uneven patterns can be formed.

The wavelength of the exposure beam is preferably shifted from the resonance center of the absorption wavelength within a range of 1/2 or less of the maximum absorption ratio of the photoresist. This is because when the wavelength of the exposure beam is set at the resonance center of absorption wavelength increases the absorption cross section σ1 of level 1 in the expression (1), equation (1) induced transition probability to the level 2 from the level 1 in the Φ _1B FIG. Because it grows. In addition, this means that the heat rate constant (thermal spontaneous release probability) K ₁ from level 2 to level 3 becomes large in Equation (1), so that the dependence on the exposure beam intensity I is reduced to control the photoresist reaction time constant t. Because it is lowered.

However, in the case where the exposure time can be extremely short, as in the case of pulsed exposure, no requirement for shifting these wavelengths is necessary (the wavelength of the exposure beam may be set in the resonance center region of the absorption wavelength). May be).

Next, formation of the fine concavo-convex pattern by the exposure process using the exposure device shown in FIG. 1 and the following developing process is demonstrated. 5A-5C are schematic cross-sectional views illustrating the step of processing the substrate W. FIGS.

In FIG. 5A, a photoresist is applied to the surface of the substrate W (by the above-described method such as spin coating) to form a photoresist layer 30. Subsequently, the substrate W is pre-baked by a clean oven (not shown).

Then, as shown in FIG. 5B, the laser beam L emitted from the exposure light source 12 and collected by the collimator lens 18 is irradiated to the surface of the substrate W, and is shown in the top view of FIG. 2. As described above, the substrate W of the substrate table 14 is scanned so that drawing (exposure) is performed on the surface of the substrate W by the focused laser beam. In Fig. 5B, portions of the photoresist already exposed are denoted by reference numerals 30A, 30A,... Represented by

After the exposure process is completed, on the surface of the substrate W, through a developing process with a developer, a rinsing process with pure water, and then a post-baking process using a clean oven (not shown). In FIG. 5C, an uneven pattern having a fine cross-sectional shape is formed.

The substrate W having such a cross-sectional shape can be used as various kinds of optical elements, for example, diffraction gratings. Further, such a substrate W has an antireflection function due to an optical confinement phenomenon based on quantum effects on a surface on which irregularities are regularly arranged.

Also, a plurality of replicas having the same cross-sectional shape can be produced through the steps to be described later, using the substrate W having the cross-sectional shape described above as the disc (mother).

Next, according to this invention, another embodiment of the method of forming an uneven | corrugated pattern, and the method of manufacturing an optical element is described. In this embodiment, after the plurality of fine uneven patterns are formed on the surface of the substrate W, the same uneven pattern is further replicated using the plurality of fine uneven patterns, and then the optical element is manufactured.

That is, the present embodiment is manufactured using a plurality of fine uneven patterns formed on the surface of the substrate W (mother) on which the stamper for transferring the fine uneven patterns is completed, and the fine uneven patterns and shapes to be transferred are substantially It is a method of manufacturing an optical element in which the same plurality of fine uneven patterns are formed on the surface of the resin material by molding using a manufactured stamper, and a plurality of optical elements are replicated.

6A to 6E are conceptual views illustrating the steps for manufacturing the stamper 46. In FIG. 6A, the cross-sectional shape of the board | substrate W which is a completed optical element is shown.

First, as shown in FIG. 6B, the conductive layer 40 is formed on the entire surface of the substrate W. As shown in FIG. The conductive layer 40 serves as a contact layer when electroless plating is performed in a subsequent step. Therefore, it is preferable that the layer thickness is minimized in the range in which a predetermined resistance can be obtained in view of shape transfer accuracy.

As a material of the conductive layer 40, copper, silver, or the like can be used, and as a layer thickness of the conductive layer 40, for example, a thickness of 0.1 μm can be employed. As a method for forming the conductive layer 40, a vacuum deposition method, a sputtering method, an electroless plating method, or the like can be used.

Subsequently, as shown in Fig. 6C, electroforming is performed, in which the nickel layer 42 is formed on the conductive layer 40 on the surface of the substrate W by electroless plating. The thickness of the nickel layer 42 may be sufficient to prevent deformation during handling and in subsequent steps of performing transfer of the Ni mother 44. Here, the nickel layer 42 formed by electroless plating has a reverse shape of a pattern formed on the surface of the substrate W as a completed optical element, and serves as a reverse mother. The inversion mother 42 is peeled from the board | substrate W. As shown in FIG.

Subsequently, as shown in FIG. 6D, electroforming is performed, in which the nickel layer 44 is formed on the inverting mother 42 by electroless plating. The thickness of the nickel layer 44 may be sufficient to prevent deformation in handling and in subsequent steps in carrying out the transfer of the stamper 46. The nickel layer 44 formed by electroless plating here has the same shape as the pattern formed on the substrate W as a completed optical element, and serves as a Ni mother. After completion of the electroforming, the Ni mother 44 is peeled off the inverting mother 42.

Subsequently, as shown in Fig. 6E, electroforming is performed, in which the nickel layer 46 is formed on the Ni mother 44 by electroless plating. Nickel layer 46 is used as a stamper. The thickness of the nickel layer 46 needs to be sufficient to withstand the conditions for use as a stamper. The nickel layer 46 formed by electroless plating here has an inverted shape of the pattern formed on the surface of the substrate W as a completed optical element.

As shown in FIG. 6E, in this step, a plurality of stampers 46 can be remanufactured from one Ni mother 44. Thus, this is advantageous when multiple sheets of optical elements are produced simultaneously, for example by multistage hot press processing. After completion of the electroforming, the nickel layer (stamper) 46 is peeled off from the Ni mother 44.

Since a plurality of fine concavo-convex patterns having substantially the same shape as the concave-convex pattern of the finished optical element (mother) on the surface of the resin material are formed by using the stamper 46, various kinds of known molding methods duplicate the optical element. It can be used as a production method. For example, it is possible to use an injection molding method, a hot press molding method, a transfer molding method for a UV cured resin, a transfer molding method for an EB cured resin, a solution casting dry curing molding method and the like. In various molding methods, it is also possible to apply not only the method using a plate-shaped stamper but also the roll forming method (for example, solution casting dry hardening molding method) using a roll-shaped stamper.

As mentioned above, embodiment of the exposure method, the uneven | corrugated pattern formation method, and the optical element manufacturing method which concerns on this invention was described. However, the present invention is not limited to the above-described embodiment, and various kinds of modes can be taken as the embodiment according to the present invention.

For example, according to the present invention, in Fig. 2, the X-axis moving stage 22 and the Y-axis moving stage 24 are driven so that substantially the entire surface of the substrate W is driven by the laser beam spot P. Exposed. However, a configuration may also be employed in which the laser beam is scanned by, for example, a polygon mirror without moving the substrate W, thereby substantially exposing the entire surface of the substrate.

Further, in the manufacture of the optical element, as shown in Fig. 6E, an inverted shape of the pattern formed on the surface of the substrate W as the completed optical element is used as the stamper 46. However, Ni mother 44 having the same shape as the pattern formed on the surface of the substrate W as a completed optical element can also be used as a stamper. In this case, the surface of the resin material formed by molding has an inverted shape of the pattern formed on the surface of the substrate W. As shown in FIG. This is because such a resin material may also function efficiently as an optical element.

In addition, in the above-mentioned embodiment, although the stamper is described as a plate-shaped member, a roll-shaped site may also be used as a stamper. In this case, as a method of manufacturing a roll-shaped stamper, a configuration in which the sheet-shaped Ni mother 44 is wound around the columnar body so that inversion molding is formed by electroforming, and the sheet-shaped Ni mother 44 is in a cylindrical shape. It is also possible to adopt a configuration in which inversion molding is formed by electroforming after being deformed so that the surface of the fine concavo-convex pattern is located on the inner peripheral side.

Further, for example, a plurality of fine uneven patterns are formed on the surface of the columnar body or the inner peripheral surface of the columnar body so that the columnar body or the columnar body is used as the substrate W, and used as the mother to form a roll-shaped stamper by electroforming. It is also possible to employ | adopt the structure to form.

In addition, a columnar body or cylinder is used as the substrate W, and a plurality of fine uneven patterns are formed on the surface of the columnar body or the inner peripheral surface of the cylindrical body, and the surface of the fine uneven pattern has a predetermined hardness so as to have a predetermined hardness. It is also possible to employ a configuration in which electroforming is carried out so that the columnar body or the cylinder body is used as a roll-shaped stamper.

Further, the ratio of the convex portion to the concave portion in the cross-sectional shape of the uneven pattern shown in FIGS. 6A to 6E may be different from the ratio of one to one shown in the figures by controlling the exposure conditions.

In addition, the step of manufacturing the stamper for transferring the fine concavo-convex pattern is not limited to the above-described embodiment. 8A to 8E are conceptual diagrams illustrating another step of manufacturing a stamper. 8A to 8E correspond to FIGS. 6A to 6E described above.

In FIG. 8A, the cross-sectional shape of the board | substrate W which is a completed optical element is shown. In the present embodiment, instead of the plurality of fine uneven patterns formed on the surface of the substrate W of FIG. 6A, a plurality of fine uneven patterns of the photoresist 30 having the same shape as the cross-sectional formation of FIG. 5C is used.

That is, in the present embodiment, a stamper for transferring a fine concavo-convex pattern is manufactured using a plurality of fine concave-convex patterns of the photoresist 30 formed on the surface of the substrate, and molded by using the manufactured stamper to produce fine A plurality of fine concavo-convex patterns substantially the same in shape as the concave-convex pattern are formed on the surface of the resin material, and a plurality of optical elements are duplicated.

First, as shown in FIG. 8B, the conductive layer 40 is formed on the entire surface of the substrate W. As shown in FIG. This step is substantially the same as in FIG. 6B. The conductive layer 40 serves as a contact layer when electroless plating is performed in a subsequent step.

Subsequently, as shown in Fig. 8C, electroforming is performed in which the nickel layer 42 is formed on the conductive layer 40 on the surface of the substrate W by electroless plating. This step is substantially the same as in FIG. 6C. The inversion mother 42 is peeled from the board | substrate W. As shown in FIG.

Subsequently, as shown in FIG. 8D, electroforming is performed in which the nickel layer 44 is formed on the inverting mother 42 by electroless plating. This step is substantially the same as in FIG. 6D. After completion of the electroforming, the Ni mother 44 is peeled off the inverting mother 42.

Subsequently, as shown in Fig. 8E, electroforming is performed in which the nickel layer 46 is formed on the Ni mother 44 by electroless plating. Nickel layer 46 is used as a stamper. This step is substantially the same as in FIG. 6E.

As shown in FIG. 8E, in this step, a plurality of stampers 46 can be remanufactured from one Ni mother 44. The present molding step using the stamper 46 is the same as in FIG. 6E.

EXAMPLE

The substrate W is exposed using the exposure device 10 shown in FIG. 1, and a plurality of fine uneven patterns are formed on the surface of the substrate W. As shown in FIG.

An Nd: YAG laser (SHG wavelength 532 nm) is used as the laser light source 16 of the exposure light source 12. Prior to the exposure, the diameter of the primary airy disk 3 (see FIG. 7) and the diameter of the secondary airy disk of the laser beam emitted from the laser light source 16 and collected by the collimator lens 18 are measured.

For the measurement, photoresist is applied and formed on the surface of the substrate W, and the laser beam is irradiated on the surface in accordance with the recommended conditions of the photoresist. After development, the profile of the irradiated part is measured by AFM. In addition, the laser beam for irradiation is measured directly by a laser beam profiler (manufactured by Gentec Corp., product name: Beam Map).

As a result, the diameter of the primary airy disk 3 at the focal position is 722 nm, and the diameter of the secondary airy disk is 1.2 µm.

As the substrate W, a substrate made of soda lime glass (float glass) having a thickness of 5 mm is used. After the substrate W is cleaned and dried, a photoresist (g-line positive photoresist) is applied and formed on the surface of the substrate W to have a layer thickness of 2 m after drying. As photoresist, Arch Corp. The product manufactured by (product name: OIR-907) is used.

In the exposure processing by the use of the exposure device 10, exposure is performed while the beam intensity and the scanning speed (actually the movement speed of the substrate W) of the laser beam are controlled, so that the reaction time constant of the photoresist is locally Exposure can be performed while controlled. Specifically, the beam intensity of the laser beam is set to I = 535 µW, and the moving speed of the substrate W in the X-axis direction is set to V = 500 µm / s. In the Y-axis direction of the substrate W, the line scan width is set to 1 m.

After exposure, development processing with a developer, rinsing processing with pure water, and post-baking processing are performed. Thereafter, the formed pattern is measured and it is confirmed that the pattern has a pattern line width of about 700 nm and a pattern depth of about 2 μm (corresponding to the layer thickness of the photoresist).

Next, as a comparative example, exposure is performed without locally controlling the reaction time constant of the photoresist. In detail, the beam intensity of the laser beam is set to I = 45 μW, and the moving speed of the substrate W in the X axis direction is set to V = 200 μm / s. In the Y-axis direction of the substrate W, the line scan width is set to 1 m.

After exposure, development processing with a developer, rinsing processing with pure water, and post-baking processing are performed. The pattern formed is then measured and found to have a pattern line width of about 750 nm and a pattern depth of about 100 nm.

In addition, as another comparative example, exposure is performed without locally controlling the reaction time constant of the photoresist. Specifically, the beam intensity of the laser beam is set to I = 535 µW, and the moving speed of the substrate W in the X axis direction is set to V = 100 µm / s. In the Y-axis direction of the substrate W, the line scan width is set to 1 m.

After exposure, development processing with a developer, rinsing processing with pure water, and post-baking processing are performed. Thereafter, the formed pattern is measured, and it is confirmed that the entire surface is exposed so that the pattern is not formed.

Claims (16)

An exposure method suitable for manufacturing a device having an uneven pattern, comprising irradiating a laser beam to a layer of photosensitive material formed to a predetermined thickness on a surface of a substrate while controlling the beam intensity and the beam scanning speed of the laser beam, comprising: And exposing the laser beam to locally control the reaction time constant of the photosensitive material. The method of claim 1, And a desired exposure width is smaller than the diameter of the airy disk of the laser beam. The method of claim 1, And the laser beam is interfering light in space and time. The method of claim 2, And the laser beam is interfering light in space and time. An exposure method suitable for manufacturing a device having an uneven pattern comprising irradiating a laser beam in a pulsed state to a layer of photosensitive material formed to a predetermined thickness on a surface of a substrate while controlling the beam intensity and the pulse width of the laser beam. , Exposure is performed by applying a laser beam in the pulse state to locally control the reaction time constant of the photosensitive material. The method of claim 5, And a desired exposure width is smaller than the diameter of the airy disk of the laser beam. The method of claim 5, And the laser beam is interfering light in space and time. The method of claim 6, And the laser beam is interfering light in space and time. Forming a layer of photosensitive material having a predetermined thickness on a surface of the substrate; Performing locally controlled exposure by applying a laser beam to the layer of photosensitive material while controlling the reaction time constant of the photosensitive material by controlling the beam intensity and the beam scan rate of the laser beam; Performing development of the layer of photosensitive material after the step of performing the exposure; And Forming a plurality of fine uneven patterns in the layer of photosensitive material. The method of claim 9, The height of the concave-convex pattern is set to 0.1 to 100㎛, the formation method of the concave-convex pattern. The method of claim 9, The substrate is a columnar or cylindrical body, a method of forming an uneven pattern. As a method of manufacturing an optical element using the method of forming the uneven pattern according to claim 9, Manufacturing a stamper to which the surface shapes of the plurality of uneven patterns are transferred using the plurality of uneven patterns formed on the surface of the substrate; And Duplicating a plurality of concave-convex patterns having substantially the same shape as the plurality of concave-convex patterns on the surface of the resin material by molding by using the stamper. The method of claim 10, The substrate is a columnar or cylindrical body, a method of forming an uneven pattern. As a method of manufacturing an optical element using the method of forming the uneven pattern according to claim 10, Manufacturing a stamper to which the surface shapes of the plurality of uneven patterns are transferred using the plurality of uneven patterns formed on the surface of the substrate; And Duplicating a plurality of concave-convex patterns having substantially the same shape as the plurality of concave-convex patterns on the surface of the resin material by molding by using the stamper. As a method of manufacturing an optical element using the method of forming the uneven pattern according to claim 11, Manufacturing a stamper to which the surface shapes of the plurality of uneven patterns are transferred using the plurality of uneven patterns formed on the surface of the substrate; And Duplicating a plurality of concave-convex patterns having substantially the same shape as the plurality of concave-convex patterns on the surface of the resin material by molding by using the stamper. As a method of manufacturing an optical element using the method of forming the uneven pattern according to claim 12, Manufacturing a stamper to which the surface shapes of the plurality of uneven patterns are transferred using the plurality of uneven patterns formed on the surface of the substrate; And Duplicating a plurality of concave-convex patterns having substantially the same shape as the plurality of concave-convex patterns on the surface of the resin material by molding by using the stamper.

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