JP2007047251A - Method of manufacturing optical element and projection type display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for simply and easily manufacturing an optical element which is excellent in optical characteristics such as transmissivity and which can be suitably used as a polarizing element or a diffraction grating or the like. <P>SOLUTION: The method comprises a step of forming a first resist layer 30 consisting of a novolak resist on a substrate 11A, a process of forming a second resist layer 31 consisting of a chemical amplification type resist containing a silylation agent on the first resist layer 30, a step of selectively irradiating the second resist layer 31 with laser beams, a step of forming a groove section 34 by carrying out dry etching by oxygen after laser beam irradiation and selectively removing an exposed section or a non-exposed section of the second resist layer 31 and the first resist layer 30 located therebelow, a step of forming a metallic layer by electroless plating at the groove section 34 and a step of removing the remaining first resist layer 30 and the remaining second resist layer 31. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical element and a projection display device.

  A liquid crystal device is used as a light modulation device in a projection display device such as a projector. As such a liquid crystal device, one having a configuration in which a liquid crystal layer is sandwiched between a pair of opposed substrates is known, and a voltage is applied to the liquid crystal layer inside the pair of substrates. An electrode is formed. Further, an alignment film that controls the alignment of liquid crystal molecules when no voltage is applied is formed inside the electrode, and an alignment film that has been rubbed on the surface of a polyimide film is known.

On the other hand, a polarizing plate is disposed on the outside of the pair of substrates (a surface side different from the surface facing the liquid crystal layer) so that predetermined polarized light is incident on the liquid crystal layer. As a polarizing plate, in addition to a polarizing film manufactured by orienting iodine or a dichroic dye in a certain direction by stretching a resin film of an organic compound in one direction, a fine pattern as disclosed in Patent Document 1 is used. A polarizing element (optical element) is known.
JP-A-8-82703

  However, in Patent Document 1, in order to obtain a fine pattern, a laminating process of forming four layers of a conductive layer, a lower layer resist, an intermediate layer, and an upper layer resist from the substrate side must be performed. Further, in order to transfer the pattern to the lower layer resist after patterning the upper layer resist, at least two dry etching steps are required. Further, after the lamination process and the dry etching process, in order to remove unnecessary portions of the conductive layer, laser irradiation must be performed, and in either case, a complicated process is required.

  The present invention has been made to solve the above problems, and provides a method for easily producing an optical element that has excellent optical characteristics such as transmittance and can be suitably used as a polarizing element, a diffraction grating, and the like. It is another object of the present invention to provide a projection display device including an optical element manufactured by the method.

  In order to solve the above-described problems, an optical element manufacturing method according to the present invention includes a step of forming a first resist layer made of a novolac resist on a dielectric substrate, and silylation on the first resist layer. A step of forming a second resist layer made of a chemically amplified resist containing an agent, a step of selectively irradiating the second resist layer with a laser beam so that an irradiation portion is striped, and After the laser beam irradiation, dry etching with oxygen is performed to selectively remove the exposed or non-exposed portion of the second resist layer and the first resist layer therebelow, and the remaining first resist layer Forming a groove surrounded by the second resist layer, forming a metal layer by electroless plating in the groove, and removing the remaining first resist layer and second resist layer And that step, characterized in that it comprises a.

According to such a manufacturing method, an optical element that does not use an organic material can be manufactured, and the manufactured optical element is extremely excellent in light resistance and heat resistance.
In addition, a metal layer as a conductor can be formed in a stripe shape on a dielectric substrate, and a metal wire grid type polarizing element can be provided by setting the pitch of the stripe to be equal to or less than the wavelength of visible light. be able to. Further, in this case, due to the difference in dielectric constant between the substrate and the metal layer, when the optical element is used as a polarizing element of a projection display device such as a projector, the transmittance and contrast are high and suitable. Become.
In addition, since the metal layer is formed by electroless plating in the groove formed by the resist, there is no need for a lamination process of 4 layers as in Patent Document 1, and in Patent Document 1, at least dry etching is performed. However, it is only necessary once in the present invention, so that the process can be simplified. Further, the formation of the metal layer by electroless plating can eliminate the dry etching of the metal layer, and as a result, there is an advantage that harmful substances such as chlorine compounds and boron compounds are not discharged during the manufacturing process.

  In the process of forming the second resist layer in the manufacturing process of the present invention, the silylating agent reacts with the OH group of the resist to introduce Si atoms into the resist surface. When a positive chemically amplified resist is used, the OH group in the polymer is silylated in the unexposed portion, but the exposed portion is difficult to be silylated because the polymer is crosslinked by the generated acid. Therefore, a pattern is formed by dry development due to the difference in silylated contrast between the exposed portion and the unexposed portion. On the other hand, in the case of a negative resist, since the OH group in the unexposed area is blocked by the acid leaving group, the exposed area is dry-developed without being silylated. As the silylating agent, any of trimethylsilyldimethylamine, dimethylsilyldimethylamine, trimethylsilyldiethylamine, dimethylsilyldiethylamine, 1,1,3,3-trimethyldisilazane, and hexamethylcyclotrisilazane can be used. By using such a silylating agent, pattern formation based on the presence or absence of the exposure described above can be reliably performed.

  Further, in the manufacturing process of the present invention, in the step of irradiating the laser beam, multi-beam interference light is irradiated. By irradiating such multi-beam interference light (interference light by two or more light beams), periodic irradiation of the wavelength order of the laser light can be realized. For example, in the case of irradiation by two-beam interference, the period interval can be controlled by controlling the angle between the beams.

  Moreover, the manufacturing process of this invention WHEREIN: Before the said electroless-plating process, the process of apply | coating tin chloride to the side surface of the 1st resist layer and the 2nd resist layer which surround the said groove part can be included. If such tin chloride is applied to the resist side surface, the wettability during plating of the resist side surface is improved.

  Further, in the production process of the present invention, in the process of forming the metal layer by electroless plating, as the metal, silver, gold, copper, palladium, platinum, aluminum, rhodium, silicon, nickel, cobalt, manganese, iron Chrome, titanium, ruthenium, niobium, neodymium, ytterbium, yttrium, molybdenum, indium, bismuth, or an alloy thereof can be used.

  Next, in order to solve the above-described problem, a projection display device of the present invention includes a light source device, a light modulation device that modulates light emitted from the light source device, and light modulated by the light modulation device. A projection type display device comprising a projection device for projecting, wherein a polarizing element is provided on a light incident side and a light emitting side of the light modulation device, and the polarizing element is manufactured by the method described above. It is characterized by comprising an element.

  Such a projection display device is very reliable. In other words, the optical element manufactured by the above-described method is a structure that does not include an organic material, and thus has excellent light resistance and heat resistance, optical characteristics such as transmittance and contrast, and manufacturing efficiency. A projection display device can be provided at low cost.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

[projector]
FIG. 1 is a schematic configuration diagram showing a main part of a projector as an embodiment of a projection display device of the present invention. The projector according to the present embodiment is a liquid crystal projector using a liquid crystal device as a light modulation device.

  In FIG. 1, 810 is a light source, 813 and 814 are dichroic mirrors, 815, 816 and 817 are reflection mirrors, 818 is an incident lens, 819 is a relay lens, 820 is an exit lens, and 822, 823 and 824 are liquid crystal devices. A modulation device, 825 is a cross dichroic prism, 826 is a projection lens, 831, 832, and 833 are incident-side polarizing plates (optical elements), and 834, 835, and 836 are output-side polarizing plates.

  The light source 810 includes a lamp 811 such as a metal halide and a reflector 812 that reflects the light of the lamp. As the light source 810, besides a metal halide, an ultrahigh pressure mercury lamp, a flash mercury lamp, a high pressure mercury lamp, a deep UV lamp, a xenon lamp, a xenon flash lamp, or the like can be used.

  The dichroic mirror 813 transmits red light contained in white light from the light source 810 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 817 and enters the red light liquid crystal light modulator 822 via the polarizing plate 831. The green light reflected by the dichroic mirror 813 is reflected by the dichroic mirror 814 and enters the liquid crystal light modulator 823 for green light via the polarizing plate 832. Further, the blue light reflected by the dichroic mirror 813 passes through the dichroic mirror 814. For blue light, in order to prevent light loss due to a long optical path, a light guide means 821 including a relay lens system including an incident lens 818, a relay lens 819, and an exit lens 820 is provided. The blue light is incident on the blue light liquid crystal light modulator 824 via the polarizing plate 833 via the light guide unit 821.

  The three color lights modulated by the respective light modulation devices 822 to 824 are incident on the cross dichroic prism 825 via the respective color polarizing plates 834 to 836. The cross dichroic prism 825 is formed by bonding four right-angle prisms. A dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an X shape at the interface. Yes. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 827 by the projection lens 826 which is a projection optical system, and the image is enlarged and displayed.

  Here, in the projector according to the present embodiment, the polarizing plates 831 to 836 employ those made of an inorganic material. Since the light source 810 composed of the metal halide lamp 811 emits high energy, the organic material may be decomposed or deformed by the high energy light. Therefore, the polarizing plates 831 to 836 are made of an inorganic material (including a metal material) having high light resistance and high heat resistance.

  2 is a perspective view showing a schematic configuration of polarizing plates 831 to 836 (hereinafter collectively referred to as polarizing plate 1), FIG. 3 is a schematic plan view of polarizing plate 1, and FIG. 4 is a schematic sectional view of polarizing plate 1. FIG. 5 and FIG. 5 are explanatory views showing the action when light passes through the polarizing plate 1.

  The polarizing plate 1 relates to the optical element of the present invention, and selects each color light emitted from the light source 810 for polarization and transmits only linearly polarized light. Specifically, as shown in FIG. 2, a plurality of non-organic materials (inorganic materials and / or metal materials) arranged in a stripe pattern on a translucent substrate 11A made of a dielectric material such as a glass substrate. The grating (fine structure) 12 is configured.

  As shown in FIG. 3, the pitch P of the grating 12 is a value smaller than the wavelength of the incident light, and is set to 140 nm or less, for example. The width of the grating 12 is set to, for example, 70 nm or less, which is convenient for manufacturing, but is more preferably about 1/10 of the wavelength of incident light. In addition, although the linear groove pattern 13 formed in the clearance gap between the grating | lattices 12 is made into space, it is good also as what inserts the translucent material different from the said grating | lattice 12, for example.

  The height of the grating 12 is about 100 nm to 200 nm. In addition to aluminum, the metal material constituting the lattice 12 is silver, gold, copper, palladium, platinum, rhodium, silicon, nickel, cobalt, manganese, iron, chromium, titanium, ruthenium, niobium, neodymium, ytterbium. , Yttrium, molybdenum, indium, bismuth, or alloys thereof can be used.

As shown in FIG. 5, the polarizing plate 1 has a refractive index n _A of the grating 12 and a refractive index n _B of the space 11 B interposed between the gratings 12. Polarization selection is performed according to the polarization direction. Specifically, linearly polarized light X having a polarization axis in a direction perpendicular to the extending direction of the grating 12 is transmitted, and linearly polarized light Y having a polarizing axis in a direction parallel to the extending direction of the grating 12 is reflected. Therefore, the polarizing plate 1 of the present embodiment has the same action as the light reflection type polarizer, that is, the action of transmitting the polarized light parallel to the optical axis (transmission axis) and reflecting the polarized light perpendicular thereto. .

  The linearly polarized light generated through the polarizing plate 1 is incident on the liquid crystal devices 822 to 824 serving as light modulation means. The liquid crystal devices 822 to 824 have a configuration as shown in FIG. 6, for example. FIG. 6 is a schematic cross-sectional view of the liquid crystal devices 822 to 824.

  The liquid crystal devices 822 to 824 are configured to include two substrates (element substrate 10 and counter substrate 20) made of a transparent substrate such as glass or plastic, and the liquid crystal layer 50 is interposed between the pair of substrates 10 and 20. It is pinched. A transparent electrode 9 made of ITO or the like is formed in a matrix on the liquid crystal layer 50 side of the element substrate 10, and further on the liquid crystal layer 50 side of the transparent electrode 9 is an alignment film 11 that regulates alignment of liquid crystal molecules. Is formed on the entire surface of the substrate.

  On the other hand, a solid transparent electrode 23 is formed on the entire surface of the counter substrate 20 on the liquid crystal layer 50 side, and further on the liquid crystal layer 50 side of the transparent electrode 23 is an alignment film 21 that regulates alignment of liquid crystal molecules. Is formed in a solid shape on the entire surface of the substrate.

  In the configuration of FIG. 6, a pair of substrates 10 and 20 are bonded together via a sealing material (not shown), and liquid crystal is sealed inside. In this case, a TN (Twisted Nematic) mode is employed as the liquid crystal mode of the liquid crystal layer 50, but an STN (Super Twisted Nematic) mode, an ECB (Electrically Controlled Birefringence) mode, and the like can also be employed.

The element substrate 10 is a translucent substrate such as glass or quartz, and includes a TFT element (not shown) that performs switching driving of voltage application to the pixel electrode 9. The pixel electrode 9 is made of a light-transmitting and conductive material such as ITO (indium tin oxide) and has a thickness of about 50 nm to 100 nm (for example, 85 nm). Further, the alignment film 11 is made of an oblique vapor deposition material of SiO ₂ and regulates the alignment of liquid crystal molecules. The alignment film 11 has a thickness of about 10 nm to 50 nm (for example, 25 nm).

On the other hand, the counter substrate 20 is composed of a light-transmitting substrate such as glass or quartz, like the element substrate 10, and has a light-transmitting and conductive property such as ITO (indium tin oxide) on the liquid crystal layer side. The common electrode 23 made of a material is formed with a film thickness of about 50 nm to 150 nm (for example, 140 nm). Further, an alignment film 21 made of an oblique vapor deposition material of SiO ₂ is formed on the liquid crystal layer side of the common electrode 23, and the film thickness is about 10 nm to 50 nm (for example, 25 nm).

  In such liquid crystal devices 822 to 824, the phase control of linearly polarized light entering through the polarizing plates 831, 832, and 833 shown in FIG. 1 is performed. That is, the drive control of the liquid crystal layer 50 is performed by the voltage applied to the electrodes 9 and 23, and the phase of the incident light is controlled. The phase-controlled light is incident on the polarizing plates 834, 835, 836 disposed on the light exit side and modulated.

  Each color light modulated by the liquid crystal devices 822 to 824 and the polarizing plates 831 to 836 is formed by being incident on the cross dichroic prism 825 as described above. The synthesized light is projected onto the screen 827 by the projection lens 826 which is a projection optical system, and the image is enlarged and displayed.

  In the present embodiment, no organic material is used for the polarizing plate 1 (831 to 836). That is, the polarizing plate 1 (831-836) is comprised from an inorganic material and / or a metal material, excluding the organic material which may be deteriorated with the high energy light supplied from a metal halide lamp. Moreover, since the said polarizing plate 1 (831-836) is manufactured by the method as shown below, manufacturing cost is also cheap and it has become very reliable.

[Production method of polarizing plate]
Hereinafter, an example of the manufacturing method of the polarizing plate (optical element) 1 shown in FIGS. 2 to 4 will be described with reference to FIGS.
First, as shown in FIG. 7, for example, OFPR manufactured by Tokyo Ohka Co., Ltd. is applied as a novolak resist to the substrate 11A made of SiO ₂ which is a translucent dielectric material by spin coating, and this is baked. Then, the first resist layer 30 is formed.

  Further, as shown in FIG. 7, for example, a positive type TDUR-P / N manufactured by Tokyo Ohka Co., Ltd. is applied on the first resist layer 30 as a chemically amplified resist containing a silylating agent (silicon compound) by spin coating. This is baked to form the second resist layer 31.

  Here, the silylating agent is a material that reacts with the OH group of the resist 31 to introduce Si atoms into the surface of the resist 31 as shown in FIG. For example, when a positive chemically amplified resist is used for the second resist layer 31, when this is selectively exposed, OH groups in the polymer are silylated in the unexposed area, but the acid generated in the exposed area As a result of the crosslinking of the polymer, it is difficult to be silylated. Therefore, a pattern is formed by dry development due to the difference in silylated contrast between the exposed portion and the unexposed portion. On the other hand, in the case of a negative resist, since the OH group in the unexposed area is blocked by the acid leaving group, the exposed area is dry-developed without being silylated. As such a silylating agent, for example, trimethylsilyldimethylamine, dimethylsilyldimethylamine, trimethylsilyldiethylamine, dimethylsilyldiethylamine, 1,1,3,3-trimethyldisilazane, hexamethylcyclotrisilazane and the like can be used.

  Next, laser irradiation is selectively performed on the formed second resist layer 31. Here, as shown in FIG. 8, it is assumed that the selective exposure is performed so that the exposed portion 32 and the non-exposed portion 31 are striped. Specifically, exposure is performed using an interference exposure method (here, two-beam interference exposure) so as to form a fine striped pattern with a pitch of 140 nm. When baking (PEB) is performed after such exposure, the silylating agent acts on the non-exposed portion 31 to effect silylation, while the exposed portion 32 crosslinks the polymer constituting the resist. , Silylation is not performed.

Subsequently, after the exposure, a step of selectively removing the exposed portion 32 and the first resist layer 30 under the exposed portion 32 by dry etching with oxygen as shown in FIG. Through such an etching process, the fine stripe-shaped groove 34 is formed surrounded by the developed first resist layer 30 and second resist layer 31. In addition, the upper layer of the non-exposed part 31 developed by dry etching is changed to SiO ₂ , and the upper layer of the non-exposed part 31 has liquid repellency.

  Furthermore, as shown in FIG. 11, in order to improve the wettability at the time of plating, a step of applying tin chloride as a catalyst to the groove part 34 surrounded by the first resist layer 30 and the second resist layer 31 is performed. Here, it is applied to the bottom and side surfaces of the groove 34 (that is, the side surfaces of the resist layers 30 and 31 surrounding the groove 34), and the lyophilic layer 33 is formed at that position.

  Thereafter, a step of depositing the metal layer 12 by electroless plating in the groove 34 is performed. Here, the silver thin film is formed by silver mirror reaction (electroless plating). That is, a method of reducing silver ions in an aqueous solution in the presence of the reducing agent (R) and precipitating silver in the groove 34 is employed. In addition to silver, the metal constituting the metal layer 12 is, for example, gold, copper, palladium, platinum, aluminum, rhodium, silicon, nickel, cobalt, manganese, iron, chromium, titanium, ruthenium, niobium, neodymium, ytterbium. , Yttrium, molybdenum, indium, bismuth, or an alloy thereof can also be used.

  Finally, a step of removing the remaining first resist layer 30 and second resist layer 31 by etching is performed. Here, the first resist layer 30 and the second resist layer 31 are selectively removed using a stripping solution 106 manufactured by Tokyo Ohka Co., Ltd. as an etchant, and a fine metal layer (on the substrate 11A as shown in FIG. The polarizing plate 1 in which the (wire grid) 12 is formed with a predetermined period can be manufactured.

  According to such a method for producing a polarizing plate, it is possible to easily produce a polarizing plate 1 that does not use an organic material, and the produced polarizing plate 1 is extremely excellent in light resistance and heat resistance. In addition, the metal layer 12 as a conductor can be formed in a striped pattern on the dielectric substrate 11A, and the pitch of the stripe is set to 140 nm (not more than the wavelength of visible light). It functions as the grid-type polarizing plate 1.

  In addition, since the metal layer 12 is formed by electroless plating in the groove 34 formed by the resists 30 and 31, no complicated lamination process is required, and only one dry etching is required, thereby simplifying the process. It is illustrated. Furthermore, in the formation of the metal layer 12 by electroless plating on the groove 34 formed between the resists, dry etching of the metal layer 12 can be omitted, and as a result, harmful substances such as chlorine compounds and boron compounds are manufactured. There is also the advantage of not discharging during the process.

  In this embodiment, an example in which an optical element having a fine structure is used as a polarizing element (polarizing plate) is shown, but it can also be used as a diffraction element, PBS (Polarized Beam Splitter), or a retardation plate. It is. In the present embodiment, the projector is exemplified as the projector, but the polarizing plate 1 can be used for a direct-view projector.

1 is a schematic diagram showing a schematic configuration of a projector according to an embodiment. The perspective view which shows typically one Embodiment of a polarizing plate. The top view which shows typically one Embodiment of a polarizing plate. Sectional drawing which shows typically one Embodiment of a polarizing plate. Explanatory drawing which shows the effect | action of a polarizing plate. FIG. 3 is a cross-sectional view schematically showing an embodiment of a liquid crystal device used as a light modulation device. Explanatory drawing which shows 1 process in the manufacturing method of a polarizing plate. Explanatory drawing which shows one process following FIG. FIG. 9 is an explanatory diagram showing one process following FIG. 8. Explanatory drawing which shows typically about silylation reaction. Explanatory drawing which shows one process following FIG. Explanatory drawing which shows one process following FIG. Explanatory drawing which shows one process following FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,831-836 ... Polarizing plate, 11A ... Board | substrate, 12 ... Metal layer (grid, fine structure), 13 ... Groove pattern, 30 ... 1st resist layer, 31 ... 2nd resist layer, 32 ... Exposure part, 34 ... Groove

Claims (6)

Forming a first resist layer made of a novolak-based resist on a dielectric substrate;
Forming a second resist layer comprising a chemically amplified resist containing a silylating agent on the first resist layer;
A step of selectively irradiating the second resist layer with a laser beam so that the irradiated portion is striped;
After the laser light irradiation, dry etching with oxygen is performed to selectively remove the exposed or non-exposed portion of the second resist layer and the first resist layer therebelow, and the remaining first resist layer Forming a groove portion surrounded by the second resist layer; and
Forming a metal layer by electroless plating in the groove,
And a step of removing the remaining first resist layer and second resist layer.   In the step of forming the second resist layer, as the silylating agent, trimethylsilyldimethylamine, dimethylsilyldimethylamine, trimethylsilyldiethylamine, dimethylsilyldiethylamine, 1,1,3,3-trimethyldisilazane, hexamethylcyclotrisilazane Either of these is used, The manufacturing method of the optical element of Claim 1 characterized by the above-mentioned.   3. The method of manufacturing an optical element according to claim 1, wherein in the step of irradiating the laser light, multi-beam interference light is irradiated.   4. The method according to claim 1, further comprising: applying tin chloride to side surfaces of the first resist layer and the second resist layer surrounding the groove before performing the electroless plating. 5. Of manufacturing the optical element.   In the step of forming a metal layer by electroless plating, the metal may be silver, gold, copper, palladium, platinum, aluminum, rhodium, silicon, nickel, cobalt, manganese, iron, chromium, titanium, ruthenium, niobium, neodymium. 5. The method of manufacturing an optical element according to claim 1, wherein any one of ytterbium, yttrium, molybdenum, indium, bismuth, or an alloy thereof is used. A projection display device comprising: a light source device; a light modulation device that modulates light emitted from the light source device; and a projection device that projects light modulated by the light modulation device.
A polarizing element is provided on a light incident side and a light emitting side of the light modulation device, and the polarizing element is constituted by an optical element manufactured by the method according to any one of claims 1 to 5. A projection type display device characterized by comprising:

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