JP4446558B2 - Curing method and apparatus using ultraviolet rays - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for curing a polymer material layer pattern formed on a substrate capable of transmitting ultraviolet rays.
As an example of a target polymer material layer pattern, a photosensitive material pattern having a three-dimensional structure is formed on a substrate in accordance with a target special surface shape, and the photosensitive material pattern is engraved on the substrate to be three-dimensional. Mention may be made of the photosensitive material pattern used in a method for producing an article having a structured surface shape.
[0002]
[Prior art]
Special surface shapes typified by spherical surfaces and aspheric surfaces have been used for the refractive surfaces and reflective surfaces of optical elements. In recent years, special surface shapes have been required for microlenses and the like in connection with liquid crystal display elements, liquid crystal projectors, and the like.
Therefore, as a method for forming the refracting surface and the reflecting surface without using molding or polishing, a method of forming a photosensitive material pattern and transferring it to a substrate has been proposed (Japanese Patent Laid-Open No. 7-230159, specially disclosed). (See Table No. 8-504515). In that method, a layer of photoresist (a representative example of a photosensitive material) is formed on the surface of an optical substrate, and the photoresist layer is exposed through an exposure mask having a two-dimensional transmittance distribution, By developing the photoresist, a convex or concave shape is obtained as the surface shape of the photoresist, and then anisotropic etching is performed on the photoresist and the optical substrate, and the surface shape of the photoresist is engraved on the optical substrate and transferred. By doing so, the shape of the refracting surface or reflecting surface having a desired three-dimensional structure is obtained on the surface of the optical substrate.
[0003]
When the surface shape of the photoresist is engraved on the optical substrate and transferred, both the photoresist and the optical substrate are etched by anisotropic etching. In order to transfer the surface shape of the photoresist to the optical substrate, an appropriate selection ratio is required with respect to the etching rate of the optical substrate and the etching rate of the photoresist. Usually, since the etching rate of the photoresist is high with respect to the optical substrate, it is necessary to improve the etching resistance of the photoresist.
[0004]
In addition, when RIE (reactive ion etching) or ICP (inductively coupled plasma) dry etching is used as anisotropic etching, the photoresist is heated by a surface reaction between the photoresist and plasma or a reaction caused by collision of ions in the plasma. Is done. Therefore, if the photoresist has insufficient heat resistance, the photoresist flows and the shape of the photoresist pattern is impaired. Therefore, it is necessary to increase the heat resistance of the photoresist.
[0005]
Recently developed high resolution positive resists with high integration and miniaturization have lower heat resistance than negative types. Also, recently developed resists for g-line (436 nm) and i-line (365 nm) have low heat resistance.
In addition, in the process targeted by the present invention, plasma etching resistance in addition to heat resistance is a characteristic required for a resist material. As a method for increasing heat resistance and plasma etching resistance, there is a method of increasing the temperature stepwise in post-baking, but sufficient heat resistance and plasma etching resistance cannot be obtained. In particular, the thicker the resist, the more difficult it is to evaporate and remove the solvent component, and sufficient heat resistance and plasma etching resistance cannot be obtained.
[0006]
Therefore, in the semiconductor process, a UV (ultraviolet) curing process of a photoresist is used. In the UV curing process, a semiconductor wafer coated with a photoresist on the front side is placed on a wafer processing table with a built-in heater under reduced pressure and heated from the back side of the wafer, while ultraviolet light is applied to the photoresist from the front side of the wafer. (See Japanese Patent No. 2798792).
As the wavelength of ultraviolet rays used in UV curing, light irradiation shorter than 300 nm is the mainstream. This is because it is considered that the heat resistance of the resist is improved by a combination of the novolak resin and the photosensitive material to cause a crosslinking reaction.
[0007]
[Problems to be solved by the invention]
When the substrate is in the atmosphere in the mechanism for heating the substrate, there are three transmission methods: air convection, heat transfer (contact between the substrate and the heating jig), and radiation. When the heating jig is placed in a vacuum, the gap between the heating plate and the substrate is also vacuum, so heat transfer due to air convection is lost, and how heat is transferred from the heating plate to the substrate And only radiation. That is, heat is hardly transmitted from the heating plate to the substrate, and the temperature difference between the heating plate surface and the substrate is increased. For this reason, it is necessary to set the heating plate set temperature higher.
[0008]
In the UV curing method described above, the photoresist is heated from the back surface of the substrate (the surface without the photoresist). That is, the thermal energy that contributes to the evaporation of the solvent in the resist is “supplied from the bottom of the resist”, whereas the vacuum environment that assists the volatilization of the solvent acts from the “resist surface”. Similarly, ultraviolet rays are irradiated from the “resist surface”. The above UV curing process is performed in a semiconductor process, and if it is to be applied as it is to a process for curing a photoresist pattern having a thick three-dimensional structure as the object of the present invention, it is as follows. Various problems arise.
[0009]
(1) Generation and residual bubbles in resist
A positive resist is N when irradiated with ultraviolet rays.₂Release gas. If a hardened layer is formed on the resist surface without completely releasing it, N₂The gas remains in the form of bubbles, causing resist rupture. This is because UV irradiation is performed from the resist surface to form a hardened surface layer, and N₂This is because the gas evaporation path is blocked. In particular, this problem becomes more apparent as the resist film thickness increases.
[0010]
(2) In the method targeted by the present invention, since the resist is thick, it is difficult for light to reach the substrate surface (lower part of the resist). In particular, when UV irradiation is performed from the resist surface, only the surface layer is cured, and this cured layer strongly absorbs light having a wavelength of 300 nm or less and prevents light from penetrating into the resist. The formation of the surface hardened layer occurs even when the organic solvent component is partially evaporated on the surface, that is, only by heating. As a result, there arises a problem that the heat resistance inside the resist is not improved and the processing time becomes long.
Further, if the set temperature of the heating plate is increased to sufficiently heat the resist in a state where the heat resistance inside the resist does not reach a predetermined temperature, the resist pattern is deformed or wrinkles are generated.
[0011]
(3) In the conventional method, the back surface of the substrate is heated by being brought into contact with the heating member, so that the back surface of the substrate may be damaged. Even if there is no problem in the case of a semiconductor wafer as in the prior art, the transmission characteristic is affected in the case of a substrate on which an optical element targeted by the present invention is formed. In order to avoid this, if a gap is provided between the back surface of the substrate and the heating member, this causes a problem that the temperature difference between the back surface of the substrate and the heating member becomes large.
An object of the present invention is to provide a method and apparatus for solving these problems and curing a pattern of a thick polymer material layer formed on a substrate.
[0012]
[Means for Solving the Problems]
The curing method of the present invention is applied when a polymer material layer formed and patterned on the surface side of a transparent glass substrate is cured. A preferred example of the polymer material layer is a photosensitive material layer, which is applied to the surface side of a transparent glass substrate and patterned according to a desired shape.
In the case of a photosensitive material layer, a photosensitive material layer is formed by applying a photosensitive material to a predetermined thickness on the surface of a substrate material on which a desired special surface shape is to be formed. A mask pattern is exposed on the photosensitive material layer using a mask designed in advance by another method.
[0013]
In the present invention, a transparent glass substrate is used. A photosensitive material layer is applied on the substrate, and the photosensitive material layer is patterned according to a desired shape. The desired shape may be a line / space like a semiconductor or a three-dimensional structure. Further, it may be a structural part for micromachining. Next, development and rinsing are carried out (PEB (post-exposure baking) if necessary). Thereafter, the resist is cured and irradiated with ultraviolet rays to improve etching resistance and heat resistance.
In the curing step, in the present invention, under a reduced pressure, ultraviolet rays in a wavelength region capable of curing the target polymer material layer and infrared rays for heating are irradiated from the back side of the transparent glass substrate.
[0014]
In the present invention, a transparent substrate is used, and ultraviolet irradiation and infrared irradiation are performed from the back side of the substrate. Curing of the polymer material layer is realized by ultraviolet irradiation, and heating of the polymer material layer is realized by infrared irradiation. By performing UV irradiation and infrared irradiation from the back side of the substrate, the polymer material layer is cured from the resist heating part side, preventing the formation of a hardened surface layer, and achieving uniform heating and high-precision temperature control by infrared irradiation. ing.
[0015]
When the resist temperature (substrate temperature) is increased and ultraviolet irradiation is performed, the curing reaction is accelerated, and the heat resistance is significantly improved by increasing the thickness of the cured layer.
The improvement in resist heat resistance is because the cross-linking reaction proceeds by ultraviolet rays, and the resist is polymerized.
When the curing process is performed under reduced pressure, the curing process can be performed in a short time. This is because moisture and solvent are removed under reduced pressure and the curing speed is increased.
[0016]
By performing infrared heating as a substrate heating method, non-uniformity of heat conduction in vacuum, difficulty of heat transfer, improvement of reproducibility, etc. are realized. This is because the curing reaction proceeds from a portion irradiated with ultraviolet rays. As the thickness of the cured layer increases, the heat resistance of the polymer material layer improves.
In the curing process, it is important to raise the substrate temperature to the required heat-resistant temperature while irradiating with ultraviolet light. It is also important how the temperature is increased, how much the irradiation intensity is increased, and what the irradiation amount is. Although there are many elements as described above, the method differs depending on the type, thickness, processing method, and the like of the resist.
[0017]
The curing apparatus of the present invention that realizes this curing method holds a transparent glass substrate having a polymer material layer pattern formed on the surface side at the periphery of the transparent glass substrate so that the polymer material layer pattern faces upward A substrate holding mechanism, an ultraviolet irradiation mechanism that is disposed below the transparent glass substrate and that irradiates the polymer material layer with ultraviolet rays in a wavelength range that can cure the polymer material layer, and the transparent glass substrate. A substrate heating mechanism that is disposed below the substrate and irradiates the polymer material layer with infrared rays for heating the polymer material layer through the transparent glass substrate; and the ultraviolet irradiation mechanism that houses the transparent glass substrate and the substrate holding mechanism. And an evacuation mechanism and an evacuation mechanism for depressurizing the inside.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The ultraviolet rays for curing the polymer material layer in the present invention preferably have a wavelength of 300 nm or less. As a light source having such a wavelength, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like can be used.
A preferred example of the ultraviolet light source is an ozone cleaning lamp that generates ultraviolet light having strong intensities near 185 nm and 254 nm. By using ultraviolet rays having these two wavelengths, the curing rate can be increased. This is because the curing speed, the thickness of the cured layer, and the heat resistance vary depending on the type of resist.
[0019]
Ultraviolet rays having two types of wavelengths may be irradiated at the same time, or may be selected and sequentially irradiated by a filter. In the case of sequential irradiation, it is preferable to first irradiate ultraviolet rays around 185 nm and then irradiate ultraviolet rays around 254 nm. Thereby, the curing rate can be further increased.
It was found that foaming can be prevented by irradiating ultraviolet rays after cutting a part of the irradiation wavelength with a filter. When the polymer material irradiated with ultraviolet rays is a photosensitive material and is a positive photoresist, the polymer chain is designed to be broken by ultraviolet rays of 300 to 500 nm. Therefore, it is preferable to use a filter to remove such wavelengths that are harmful to the curing process.
[0020]
It is preferable to selectively use the wavelength of the ultraviolet rays to be irradiated according to the target polymer material and to properly use the irradiation timing. This is because the temperature at the time of irradiation is more dominant than the intensity of ultraviolet irradiation, and the curing rate increases when irradiated while increasing the temperature.
In the irradiation with ultraviolet rays, it is preferable to first reduce the irradiation intensity and then increase the irradiation intensity. When the photosensitive material layer is thick, when it is irradiated with strong ultraviolet rays from the beginning, it foams and bubbles remain in the photosensitive material layer or burst, and the photosensitive material pattern is damaged. In order to prevent this, it is preferable to first irradiate with weak UV intensity for several seconds to 30 seconds to release gas that causes foaming.
Infrared rays are preferably infrared rays having a wavelength of 0.8 μm to 5.0 μm.
[0021]
The curing device of the present invention is characterized in that the substrate holding mechanism holds the substrate at the periphery of the substrate, and the ultraviolet lamp and the infrared lamp for heating the substrate are arranged on the back side of the substrate. Are preferably arranged in parallel and arranged so as not to interfere with each other. Furthermore, it is preferable to install an auxiliary reflector so that the illuminance and intensity are uniform.
As shown in the examples, the ultraviolet lamp and the infrared lamp are preferably irradiated after the infrared lamp is first irradiated and the polymer material layer reaches a predetermined temperature, and then the ultraviolet lamp is irradiated.
[0022]
The vacuuming period starts simultaneously with the irradiation of the infrared lamp.
The curing method of the present invention can be applied to a polymer material layer other than the photosensitive material layer. Examples of such a polymer material layer include ink, an adhesive, a paint, and a surface treatment film.
[0023]
【Example】
FIG. 1 shows an embodiment of the curing apparatus of the present invention.
Reference numeral 2 denotes a vacuum chamber of a decompression container, in which a substrate holder 4 of a substrate holding mechanism is provided. The substrate holder 4 holds the transparent glass substrate 6 having the polymer material layer pattern formed on the surface side at the periphery of the substrate 6 so that the polymer material layer pattern faces upward.
[0024]
The lower surface of the vacuum chamber 2 is an entrance window of a synthetic quartz plate, and ultraviolet rays for curing the polymer material layer and infrared rays for heating the polymer material layer through the entrance window are vacuum chambers. 2, the polymer material layer pattern formed on the surface thereof is irradiated through the transparent glass substrate 6. The vacuum chamber 2 is provided with a vacuum pump 10 via a pressure control mechanism (valve) 8 for controlling the exhaust speed in order to bring the inside into a reduced pressure state.
The vacuum chamber 2 is further provided with a nitrogen supply mechanism 12 for supplying nitrogen to be introduced when the vacuum chamber 2 leaks (releases the vacuum), and a vent 14 for discharging the nitrogen from the vacuum chamber 2.
[0025]
A load is placed on the side of the vacuum chamber 2 so that the work can be continued without breaking the vacuum in the vacuum chamber 2 when the substrate 6 is placed on the substrate holder 4 or removed from the substrate holder 4. A lock chamber 16 is provided. Reference numeral 18 denotes a substrate carrier that accommodates the substrate 6 before and after the curing process. The substrate is transferred between the substrate carrier 18 and the load lock chamber 16 by the transfer robot 20.
An illuminating device including a UV (ultraviolet irradiation) lamp 22 that irradiates ultraviolet rays through an incident window and an infrared lamp 24 that irradiates infrared rays is disposed below the vacuum chamber 2. Reference numeral 26 denotes a power source for the UV lamp 22, and reference numeral 28 denotes a cooling device having a Peltier element for cooling the UV lamp 22. Although not shown, the lamp 22 and the infrared lamp 24 are provided with a shutter, a filter, and an auxiliary reflector for equalizing the irradiation intensity.
[0026]
A power supply device 30 supplies necessary power to each unit. An outer frame surrounded by a broken line means the entire curing device, and 32 is an air conditioning control device for controlling the cleanliness of the entire curing device.
As the UV lamp 22, three lamps for UV ozone cleaning (QOL350U-3: 350W manufactured by Iwasaki Electric Co., Ltd.) were used. This lamp emits main ultraviolet wavelengths of 185 nm and 254 nm. Which of these wavelengths is used is automatically controlled by a filter installed in the irradiation apparatus. The irradiation intensity is variable from a maximum of 70 mW to a minimum of 24 mW by changing the irradiation distance.
[0027]
(Example 1)
(In the case of production of micro dimension MLA for liquid crystal)
Example 1 is an example in which the present invention is applied to manufacture of a fine pitch MLA (micro lens array).
In the MLA for liquid crystal projectors, the pixel size for 0.9 "-XGA is 18 μm × 18 μm. In this MLA, if there are 1 μm lens non-forming portions on both sides of the lens, 17 μm × 17 μm The MLA area occupying the microlens area and occupying the entire area is
17 × 17/18 × 18 = 289/324 = 89.2 (%)
Thus, even if all the light can be collected effectively by the MLA, the light collection efficiency is only 89.2%. That is, it is important to reduce the area of the MLA non-formation part in order to improve the light utilization efficiency.
[0028]
Therefore, here, a reticle for a minute pitch MLA in which the interval between adjacent microlenses is made as close to zero as possible is prepared in advance. The reticle will be described. Since a 1 / 5-fold (reduced) stepper is used, the actually manufactured reticle pattern size is 90 μm × 90 μm. This one MLA is divided into 3.0 μm unit cells, and is divided into vertical × horizontal = 30 × 30 (pieces) = 900 (pieces) unit cells. Next, cell No. 1 (all chromium remaining) is placed in the center 2 × 2 unit cell (6 μm × 6 μm on the reticle and 1.2 μm × 1.2 μm in the actual pattern). . The four corners of the lens are cell No. Place 80 (no chrome remaining). No. The “opening area” corresponding to each “gradation” is associated with the cells 1 to 80. This relationship is obtained from the exposure process and the resist sensitivity curve. Of course, if the resist material or process is different, it is necessary to grasp the sensitivity curve each time.
[0029]
Next, a process of manufacturing an MLA for a liquid crystal projector using the reticle as a mask will be described.
A neoceram substrate having a diameter of 8 inches is prepared, and a positive photoresist TGMR-950 (manufactured by Tokyo Ohka) is applied on the substrate to a thickness of 7.9 μm.
Next, this substrate was pre-baked at 90 ° C. for 180 seconds using a hot plate. The substrate was exposed using the reticle mask with the 1/5 stepper. The shape of the reticle is that of the MLA specification for a liquid crystal projector. The exposure conditions are defocus amount: +10 μm, irradiation amount: 390 mW × 1.92 seconds (illuminance: 720 mJ). The distance between the lenses after exposure is almost zero. The sign of the defocus amount + means that the focus of light to be projected and exposed is above the resist surface.
Thereafter, PEB was performed at 110 ° C. for 180 seconds.
[0030]
The exposed photoresist was developed and rinsed to form a resist pattern. The resist height after rinsing was 5.0 μm.
Next, the resist was cured by evacuation while irradiating with ultraviolet rays for 210 seconds with the ultraviolet curing device of FIG. The UV curing conditions of the present embodiment are that the substrate 6 is carried in by the automatic transfer device 20 and then the vacuuming valve 8 is opened to start vacuuming. The vacuuming is roughly evacuated to 1 Pa in 60 seconds, and then maintained at 0.9 Pa with a dry pump. The substrate 6 is heated by irradiating infrared rays from the infrared lamp 24 at the same time as evacuation is started. The substrate temperature is raised to 60 ° C. within 60 seconds and maintained. Thereafter, the resist is irradiated with ultraviolet rays of 185 nm for 30 seconds to perform initial curing slowly. Next, while maintaining the temperature, the resist is cured by irradiation with ultraviolet rays of 256 nm for 120 seconds.
[0031]
Switching between wavelengths of 185 nm and 254 nm was performed by replacing the filter after closing the shutter once. Illuminance is low at 185 nm and 24 mW / cm²254nm is 50mW / cm high²It is. During this time, the degree of vacuum remains maintained. When the shape of the resist pattern was measured after the curing process, there was no change from before the curing process.
This UV curing process improves the plasma etching resistance and heat resistance of the resist, and can withstand processing in the next process.
[0032]
The substrate 6 that has undergone the UV curing process is set in an ICP dry etching apparatus, and the degree of vacuum is 1.5 × 10.^-3 At Toor, the reaction gas is CHF._Three: 5.0 sccm, CF_Four: 50 sccm, O₂: 20 sccm, dry etching was performed under conditions of substrate bias power: 600 W, upper electrode power: 1.25 KW, substrate cooling temperature: −20 ° C. At this time, the substrate bias power and the upper electrode power were changed with time, and etching was performed while changing the selection ratio (substrate etching rate / resist etching rate) to increase with time. The average etching rate of the substrate was 0.63 μm / min, but the actual etching time required 11.5 minutes. The lens height after etching was 5.33 μm. The glass surface after etching did not become rough and showed good heat resistance and plasma etching resistance.
[0033]
(Example 2)
As Example 2, a Fresnel lens was manufactured. In this example, a 65-band Fresnel lens having a substrate material: BK-7, a focal length: f = 6.25 (mm), and a numerical aperture: NA = 0.4 (10λ gap) was manufactured as a Fresnel lens.
FIG. 2 shows a part of the right portion of the Fresnel lens 42 from the optical axis O, where t is the thickness of the substrate, h (n) (n = 1, 2, 3...) Is the light. The surface height from the axis O to each annular zone, ΔZ (n) is the sag amount representing the depth from the surface of each annular zone to the valley, and θ is the inclination angle.
[0034]
Here, the aspherical expression Z (n) representing the curved surface shape of each annular zone of the Fresnel lens is:
Z (n) = ch (n)²/ {1+ (1- (K + 1) c²h (n)²)^1/2}
+ Ah (n)^Four+ Bh (n)⁶+ Ch (n)⁸+ Dh (n)^Ten
The surface height: h (n) is
h (n) = (X²+ Y²)^1/2
And the inclination angle θ is
θ = arctan (dz / dh)
And the slope dz / dh is
dz / dh = ch (n)²/ {(1- (K + 1) c²h (n)²)^1/2}
+ 4Ah (n)^Three+ 6Bh (n)^Five+ 8Ch (n)⁷+ 10Dh (n)⁹
It is. Also,
Design wavelength λ = 780 (nm),
Substrate thickness t = 1 ± 0.05 (mm)
(Parallelity: 0.1 μm or less at φ5 mm),
The refractive index of the substrate n = 1.5118,
Back focus BF = 5.588268
It is. Each aspheric coefficient is
c = 1 / R
= 0.3133003251 (curvature radius R = 3.1944855),
K = −0.879855532,
A = −0.00105951,
B = 6.20613 × 10^-6,
C = 0,
D = 0
It is. Moreover, the result of having calculated the amount of sag of 1 to 65 annular zones is shown in FIGS.
[0035]
Based on the above, a 65-zone Fresnel lens was designed, but with the design values shown in FIGS. Since there is a difference of about .5 μm, the lens design was corrected so that the height of each annular zone of the Fresnel lens was the same height of 15.5 μm, and a Fresnel lens was manufactured with this corrected value.
In the case of a Fresnel lens, the curvature of the outer ring is increased, so the unit cell shape is a square of 2 μm × 2 μm, the dot shape is a circle (a method of increasing the area concentrically), and the dot arrangement is the center arrangement A density distribution mask was manufactured.
[0036]
From the sensitivity curve of the resist and the above formula, the concentration distribution mask pattern No. The density distribution mask was manufactured.
Next, an example of a Fresnel lens manufactured using the mask will be described.
A BK-7 glass substrate was prepared, and the TGMR-950 resist (product of Tokyo Ohka Kogyo Co., Ltd.) was applied on the substrate to a thickness of about 8.5 μm. Next, pre-baking was performed at 90 ° C. with a baking time of 180 seconds using a hot plate.
The substrate was exposed with a 1 / 2.5 stepper. The exposure conditions are defocus: +5 μm, irradiation amount: 390 mW × 1.92 seconds (illuminance: 720 mJ).
[0037]
After exposure under these conditions, PEB was carried out at 110 ° C. for 3 minutes. The resist height at this time was 7.5 μm. Thereafter, development and rinsing were performed to form a resist pattern.
Next, the resist was cured by evacuation while irradiating with ultraviolet rays for 210 seconds with the ultraviolet curing device of FIG. By this operation, the plasma etching resistance and heat resistance of the resist are improved, and the resist can withstand processing in the next process.
[0038]
In the UV curing conditions of this embodiment, after the substrate 6 is carried in by an automatic conveyance device, the vacuuming valve 8 is opened to start vacuuming. Roughing to 1 Pa in 60 seconds. Then, it maintains at 0.95 Pa with a dry pump. Substrate heating is started by irradiating infrared rays from the infrared lamp 24 at the same time as evacuation starts, and substrate heating starts. Raise to 55 ° C and maintain within 60 seconds. Thereafter, ultraviolet rays of 185 nm are irradiated for 20 seconds to perform initial curing slowly. Next, while maintaining the temperature, the resist is cured by irradiation with ultraviolet rays of 254 nm for 130 seconds.
[0039]
Switching between the wavelengths of 185 nm and 254 nm was performed by replacing the filter after closing the shutter once. Illuminance is low at 185 nm and 24 mW / cm²254nm is 55mW / cm high²It is. During this time, the degree of vacuum remains maintained. When the resist shape was measured after the curing process, there was no change from before the curing process.
[0040]
The substrate 6 that has undergone the UV curing process is set in an ICP dry etching apparatus, and the degree of vacuum is 1.5 × 10.^-3 At Toor, the reaction gas is CHF._Three: 10.0sccm, CL₂: 1.0 sccm, CF_Four: 15.0 sccm, O₂: 0.9 sccm, dry etching was performed under conditions of substrate bias power: 1 KW, upper electrode power: 1.25 KW, substrate cooling temperature: −20 ° C. At this time, etching was performed while changing the substrate bias power and the upper electrode power over time and changing the selection ratio to increase with time. The average etching rate of the substrate was 1.17 μm / min, and the average selectivity was 2.07. The lens height after etching was 15.55 μm. The actual etching time required 13.5 minutes.
[0041]
【The invention's effect】
When the curing method and curing apparatus using ultraviolet irradiation according to the present invention are used, the following effects can be obtained and various problems can be solved.
(1) Since heating is performed from the back side of the polymer material layer by infrared irradiation, the temperature distribution in the substrate can be controlled, and the generation and remaining of bubbles in the resist can be suppressed.
(2) The temperature distribution in the substrate has become smaller. Resist curing is possible from the substrate side, and thermal deformation and wrinkle generation are eliminated, and the resist is no longer thermally deformed by heat.
(3) Complete curing was possible even when the resist thickness was 7 μm or more. Thus, even if the resist is thick, heat resistance is no longer insufficient.
(4) By performing ultraviolet irradiation and infrared irradiation from the side opposite to the side where the polymer material is present, the entrance window on the lamp side is no longer contaminated due to evaporation of the solvent and the resist itself. Maintenance time has been reduced.
(5) Curing conditions can be set according to the type of resist, so that many resists can be cured, and a curing effect can be obtained regardless of the type of resist.
(6) Scratches on the back of the substrate no longer occur. In addition, there is no need to provide a gap between the substrate and the heater as in the case of using a heater, and no difference in the substrate temperature is caused by providing the gap.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a curing device.
FIG. 2 is a cross-sectional view showing a part of a Fresnel lens.
FIG. 3 is a diagram showing 1 to 4 zones of the designed Fresnel lens.
FIG. 4 is a diagram showing 4 to 15 ring zones of the Fresnel lens.
FIG. 5 is a diagram showing 15 to 33 annular zones of the Fresnel lens.
FIG. 6 is a view showing 33 to 58 annular zones of the Fresnel lens.
FIG. 7 is a view showing the 58 to 65 annular zones of the Fresnel lens.
[Explanation of symbols]
2 Vacuum chamber
4 Board holder
6 Transparent glass substrate
10 Vacuum pump
22 UV lamp
24 Infrared lamp

Claims (10)

In a method of curing a polymer material layer formed and patterned on the surface side of a transparent glass substrate,
A curing method comprising irradiating ultraviolet rays in a wavelength region capable of curing the polymer material layer and infrared rays for heating from the back side of the transparent glass substrate under reduced pressure. The curing method according to claim 1, wherein the polymer material layer is a photosensitive material layer, which is applied to the surface side of a transparent glass substrate and patterned according to a desired shape. The curing method according to claim 1, wherein the ultraviolet ray has a wavelength of 300 nm or less. The curing method according to claim 3, wherein the ultraviolet rays are ultraviolet rays having strong intensities near 185 nm and 254 nm. 5. The curing method according to claim 4, wherein the irradiation with ultraviolet rays is performed by first irradiating ultraviolet rays around 185 nm and then irradiating ultraviolet rays around 254 nm. 5. The curing method according to claim 4, wherein the irradiation with ultraviolet rays first reduces the irradiation intensity and then increases the irradiation intensity. The curing method according to claim 1, wherein the infrared ray is an infrared ray having a wavelength of 0.8 μm to 5.0 μm. A substrate holding mechanism for holding a transparent glass substrate having a polymer material layer pattern formed on the surface side at the periphery of the transparent glass substrate so that the polymer material layer pattern faces upward;
An ultraviolet irradiation mechanism disposed below the transparent glass substrate and irradiating the polymer material layer with ultraviolet rays in a wavelength region capable of curing the polymer material layer, through the transparent glass substrate;
A substrate heating mechanism that is disposed below the transparent glass substrate and irradiates the polymer material layer with infrared rays for heating the polymer material layer through the transparent glass substrate;
A decompression container that houses the transparent glass substrate and the substrate holding mechanism, has an entrance window through which ultraviolet rays from the ultraviolet ray irradiation mechanism and infrared rays from the substrate heating mechanism are incident, and has an exhaust mechanism to reduce the inside to a reduced pressure state And a curing device. The curing device according to claim 8, wherein the ultraviolet irradiation mechanism includes an ozone cleaning lamp that generates ultraviolet rays having strong intensities near 185 nm and 254 nm. The curing apparatus according to claim 8 or 9, wherein the ultraviolet irradiation mechanism includes wavelength selection means for selecting a wavelength to be irradiated.

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