WO2010150550A1 - Optical element, illumination apparatus, exposure apparatus, and method for manufacturing device - Google Patents

Abstract

Disclosed is an optical element which contains a carbon nanotube assembly in a region that is irradiated with light.

Description

Optical element, illumination apparatus, exposure apparatus, and device manufacturing method

The present invention relates to an optical element, an illumination apparatus, an exposure apparatus, and a device manufacturing method.

Conventionally, in an exposure apparatus, it has been necessary to accurately measure the amount of illumination light (exposure light) that illuminates the mask in order to control the exposure amount. Therefore, the exposure apparatus is provided with an integrator sensor that detects the amount of illumination light divided by a half mirror or the like provided in the illumination optical system. Further, an ND (darkening) filter that reduces the energy density of the illumination light in accordance with the light reception allowable range of the integrator sensor is provided between the integrator sensor and the half mirror that divides the illumination light. As the ND filter, a ND film formed on a transparent substrate made of quartz glass or the like has been used.

JP 2002-033259 A

However, since the ND filter using a chrome film has a high reflectivity, there is a problem that scattered light reflected by the ND filter becomes stray light in the housing (integrator box) of the illumination optical system.

An object according to the present invention is to provide a low-reflection optical element, and an illumination apparatus, an exposure apparatus, and a device manufacturing method using the optical element.

The optical element according to an aspect of the present invention includes a carbon nanotube aggregate in a region irradiated with light.

An illuminating device according to an aspect of the present invention is an illuminating device that illuminates an object with light emitted from a light source, and includes an optical element to which light from the light source is supplied. It has an element.

An illuminating device according to an aspect of the present invention is an illuminating device that illuminates an object with light emitted from a light source, and includes the optical element in the vicinity of an optical path of light from the light source.

An illuminating device according to one aspect of the present invention is an illuminating device that illuminates an object with light emitted from a light source, and includes the optical element described above and a measuring device that measures light via the optical element. A detection device is provided.

An exposure apparatus according to an aspect of the present invention is an exposure apparatus that illuminates a mask with exposure light and exposes a substrate with the exposure light from the mask. A lighting device is provided.

An exposure apparatus according to an aspect of the present invention includes: an illumination optical system that illuminates a mask with exposure light; and a projection optical system that projects an image of a mask pattern illuminated with the exposure light onto the substrate. At least one of the optical system and the projection optical system has the optical element described above on the optical path of the exposure light or at a position facing the optical path.

A device manufacturing method according to an aspect of the present invention includes exposing a substrate coated with a photosensitive agent using any of the exposure apparatuses described above and developing the exposed substrate. .

According to the aspect of the present invention, a low reflection optical element can be provided. Moreover, according to the aspect of this invention, the illuminating device and exposure apparatus with which stray light was reduced can be provided.

The perspective view which shows the optical element which concerns on embodiment. Sectional drawing of the optical element which concerns on embodiment. Sectional drawing which shows the other aspect of the optical element which concerns on embodiment. Sectional drawing which shows the other aspect of the optical element which concerns on embodiment. The figure which shows the manufacturing apparatus of a carbon nanotube aggregate. The figure which shows the exposure apparatus which concerns on embodiment. The flowchart which shows an example of the manufacturing process of a device. The graph which shows the measurement result of the transmittance | permeability and reflectance which concern on an Example. The graph which shows the angle characteristic of the reflectance which concerns on an Example. The graph which shows the OD value which concerns on an Example, and the measurement result of a reflectance. The graph which shows the relationship between CNT length and OD value which concern on an Example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

(Optical element)
FIG. 1 is a perspective view showing an optical element according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the optical element shown in FIG.
In the optical element 100, a CNT layer 102 made of a carbon nanotube aggregate oriented substantially perpendicular to the surface 101a is formed on one surface 101a of a substrate 101.

As the substrate 101, a substrate made of an arbitrary material can be used. For example, quartz glass, silicon single crystal, various ceramics or metal substrates can be used. The material of the substrate may be appropriately selected according to the function required for the optical element. For example, when the optical element 100 is used as an ND (darkening) filter, a transparent substrate such as quartz glass is used as the substrate 101. On the other hand, when the optical element 100 is used as a light absorbing element, the substrate 101 does not need to be transparent, and a substrate made of silicon, ceramics, metal, or the like can be used.

The CNT layer 102 is composed of carbon nanotubes (aggregate of carbon nanotubes) that stand on the surface 101a of the substrate 101 with high density. The CNT layer 102 may be formed by directly growing carbon nanotubes on the substrate 101, or may be formed by bonding a carbon nanotube aggregate formed using another substrate to the substrate 101. . The CNT layer 102 may be formed on both surfaces of the substrate 101 or may be partially formed on the surface 101a.
The orientation direction of the aggregate of carbon nanotubes is not limited to the normal direction of the surface 101a, and can be any direction. The CNT layer 102 may include a plurality of aggregates of carbon nanotubes having different orientation directions.

Since the CNT layer 102 is composed of an aggregate of carbon nanotubes, it is black and excellent in light absorption, and extremely low transmittance and reflectance can be obtained. This is because the CNT layer 102 has a structure in which a large number of carbon nanotubes are bundled, so that the light irradiated to the CNT layer 102 is absorbed by the carbon nanotubes before reaching the substrate 101. This is probably because of this.
That is, the CNT layer 102 exhibits excellent light absorption by absorption being promoted by a structure in which many carbon nanotubes are accumulated in a bundle in addition to absorption by the black carbon nanotubes themselves. In particular, the latter action becomes remarkable when the direction in which light enters and the alignment direction of the carbon nanotubes in the CNT layer 102 substantially coincide. This is because when fine needle-like carbon nanotubes extend in the direction in which light is incident, the light incident on the CNT layer 102 is reflected and reflected between the carbon nanotubes before reaching the substrate 101. This is considered to be because it is converted into thermal energy every time and attenuates.

The optical element 100 can be suitably used as an ND filter or a light absorbing element by utilizing the above light absorbing action by the CNT layer 102.
When the optical element 100 is used as an ND filter, the CNT layer 102 functions as a light amount adjustment film in the ND filter. For example, when the CNT layer 102 having a thickness of about 100 μm is formed, the transmittance is less than 0.02%, and an ND filter having an OD (Optical Density) value of about 5 to 6 can be configured. Note that the thickness of the CNT layer 102 is not limited to about 100 μm. For example, the length can be about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, or longer.

The transmittance of the optical element 100 is related to the thickness of the CNT layer 102. By making the CNT layer 102 thinner, the transmittance can be increased and the OD value can be controlled to a desired value. That is, the transmittance (OD value) of the optical element 100 can be controlled by adjusting the length of the carbon nanotubes in the carbon nanotube aggregate constituting the CNT layer 102.

Alternatively, the transmittance of the optical element 100 can be adjusted by the area density of the carbon nanotubes constituting the carbon nanotube aggregate. By reducing the area density of the carbon nanotubes constituting the aggregate of carbon nanotubes, the amount of light transmitted through the gaps between the carbon nanotubes can be increased, and the transmittance of the optical element 100 can be increased (the OD value is decreased). it can. On the other hand, by increasing the area density of the carbon nanotubes in the aggregate of carbon nanotubes, the amount of light absorbed by the carbon nanotubes can be increased, and the transmittance of the optical element 100 can be decreased (the OD value is increased).

The reflectance of the optical element 100 is very low, less than 0.2%, when the length and area density of the carbon nanotubes in the CNT layer 102 are large to some extent and there is almost no gap through which light passes through the CNT layer 102. Become. As an ND filter or a light absorption element, there is almost no advantage of adjusting the reflectance, but when the carbon nanotubes constituting the CNT layer 102 are extremely short or the area density is extremely low, the length of the carbon nanotubes or The reflectance can be adjusted by changing the area density.
Therefore, in the CNT layer 102, when the carbon nanotubes are sufficiently long or formed with a sufficiently large area density, the optical element 100 becomes a substantially non-reflective and substantially non-transmissive optical element, and the carbon nanotubes Is short or has a small area density, it becomes a substantially non-reflective and substantially semi-transmissive optical element.

On the other hand, when the optical element 100 is used as a light absorption element, the CNT layer 102 functions as a light absorption film in the light absorption element. Also in this case, similarly to the case where the optical element 100 is used as an ND filter, the length and area density of the carbon nanotubes in the CNT layer 102 are appropriately set, thereby obtaining a light absorbing element that exhibits a desired light absorbing action. be able to. That is, as the carbon nanotubes in the CNT layer 102 are lengthened and the area density of the carbon nanotubes is increased, the absorbance of the light absorbing element can be increased.

In another embodiment, the optical element can be configured as shown in FIG. FIG. 3 is a cross-sectional view showing an optical element according to another embodiment.
In the optical element 100 </ b> A, a metal film 103 is formed between the substrate 101 and the CNT layer 102. Any metal or alloy can be used as the metal film 103, and the film thickness t is not particularly limited. The material, film thickness, and the like of the metal film 103 can be appropriately set according to the use of the optical element 100.

The optical element 100 </ b> A can also be used as an ND filter or a light absorbing element that utilizes the light absorbing action of the CNT layer 102, similarly to the optical element 100 illustrated in FIGS. 1 and 2.
When the optical element 100 </ b> A is used as an ND filter, chromium or the like conventionally used for ND filters can be used as the metal film 103. In the ND filter using the optical element 100 </ b> A, the transmittance (OD value) of the optical element 100 </ b> A can be adjusted by the film thickness of the metal film 103. That is, the metal film 103 can function as a light amount adjustment film in the ND filter.
Since the metal film 103 can be formed using a conventionally known film formation method such as a sputtering method, the film thickness can be controlled with relatively high accuracy and can be formed to have a uniform film thickness. Therefore, the transmittance can be controlled with higher accuracy than when the transmittance is adjusted by the length or area density of the carbon nanotubes in the CNT layer 102.
In the optical element 100A, the CNT layer 102 only needs to have a sufficient function as an antireflection layer. Therefore, the length and area density of the carbon nanotubes constituting the CNT layer 102 are the same as those of the optical element 100 shown in FIG. It can be made smaller.

On the other hand, when the optical element 100A is used as a light absorbing element, an excellent light absorbing action can be obtained only by the CNT layer 102, so that the metal film 103 hardly requires a light absorbing action. Therefore, as the metal film 103, a film made of any metal or alloy can be formed. However, a metal or alloy that can improve the adhesion strength between the CNT layer 102 and the substrate 101, or a metal that can be used for carbon nanotube growth control. Alternatively, an alloy can be used.

Furthermore, in another embodiment, the optical element can be configured as shown in FIG. FIG. 4 is a cross-sectional view showing an optical element according to another embodiment.
In the optical element 100, an adhesive portion 104 may be formed in order to increase the adhesion strength between the CNT layer 102 and the substrate 101. A resin material or the like can be used for the bonding portion 104, but is not particularly limited as long as the material can fix the CNT layer 102 to the substrate 101.
For example, the bonding portion 104 is formed by forming a CNT layer 102 on the substrate 101, applying a resin material or the like from the CNT layer 102 side, and curing the carbon nanotubes constituting the CNT layer 102 on the base end side. be able to. By providing such an adhesive portion, peeling of the CNT layer 102 can be prevented.

The bonding portion 104 may fix the entire CNT layer 102, but as shown in FIG. 4, it is formed only on the base end side of the carbon nanotubes that stand on the substrate 101, and the surface of the CNT layer 102 Can be prevented from being formed. This is because when the bonding portion 104 is exposed on the surface of the CNT layer 102, the reflectance of the optical element 100 increases due to reflection of light by a resin material or the like constituting the bonding portion 104.

In addition, the adhesion part 104 can be formed without a problem also in the optical element 100A shown in FIG. Also in this case, the same effect as the case where the adhesion part 104 is formed in the optical element 100 can be obtained.

[Method for Manufacturing Optical Element]
Hereinafter, a method for manufacturing the optical element 100 shown in FIGS. 1 and 2 will be described.
The optical element 100 can be manufactured by growing carbon nanotubes on a substrate 101 and forming a CNT layer 102 made of a carbon nanotube aggregate on the substrate 101. More specifically, a production method including a catalyst particle forming step, a reduction step, and a CVD step is preferable.
The catalyst particle forming step is a step of forming catalyst particles on the substrate. A reduction process is a process of reducing catalyst particles and imparting catalytic activity. The CVD process is a process of growing carbon nanotubes using catalyst particles as a starting point.
Hereinafter, it demonstrates in detail for every process.

<Catalyst particle formation step>
First, the substrate 101 is prepared. As a material of the substrate 101, quartz glass, silicon single crystal, various ceramics and metals can be used. The size and thickness of the substrate 101 are arbitrary and can be selected according to the use of the optical element 100 to be manufactured.
In addition, when the heat capacity of the substrate 101 is large, technical difficulties are involved in rapid heating after the reduction step. Considering manufacturability, the thickness of the substrate can be 5 mm or less. The thickness of the substrate is not limited to 5 mm or less.
Further, the surface shape of the substrate 101 can be processed into a smooth surface having a surface roughness (RMS) of several nm or less in order to form metal catalyst particles having a desired particle diameter.
If the substrate 101 is prepared, it is precisely cleaned with a detergent, water, an alcohol solvent or the like under ultrasonic vibration as a pretreatment if necessary. This is for uniformly forming metal catalyst particles having a desired particle diameter.

Next, as the metal catalyst particles formed on the substrate 101, a metal that acts as a catalyst for carbon nanotube growth is used. Specifically, at least one metal selected from the group consisting of cobalt, molybdenum, nickel, and iron, or an alloy made of these metals can be used.
The particle size of the metal catalyst particles is adjusted according to the number of graphene sheet layers of carbon nanotubes to be produced. For example, when producing single-walled carbon nanotubes, a metal catalyst particle group having a particle size of 8 nm or less is formed on the substrate 101. In the case of producing a double-walled carbon nanotube, a metal catalyst particle group having a particle size of 8 nm or more and 11 nm or less (preferably more than 8 nm and 11 nm or less) is formed on the substrate 101. The larger the particle diameter of the metal catalyst particles, the more carbon nanotubes can be formed. The particle size of the metal catalyst particle group is not limited to 8 nm or less or 11 nm or less.

A first method for forming metal catalyst particles having a desired particle diameter on the substrate 101 is a method using magnetron sputtering.
First, the substrate 101 is stored in a film forming chamber of a magnetron sputtering apparatus and evacuated to a high vacuum. Next, a rare gas such as argon gas is introduced into the film formation chamber, and the pressure is adjusted to a range of 0.1 Pa to 3 Pa. A target made of the above-described metal or alloy is used as a target, and sputtering is performed by applying a negative high voltage to the target. Monoatomic or cluster-sized metal catalyst particles released from the target surface by sputtering adhere to a substrate disposed opposite to the target.

The particle size of the metal catalyst particles on the surface of the substrate 101 can be adjusted by sputtering conditions, and the particle size can be reduced as the power input to the target is reduced and the discharge time is shortened. Specifically, for example, the power density can be adjusted in the range of 0.2 to 1 W / cm ² and the discharge time can be adjusted in the range of 1 second to several tens of seconds.
Further, the distribution (variation) of the particle diameter of the metal catalyst particles can be adjusted by the discharge time. That is, as the discharge time is shortened, the particle size variation can be reduced, and by selecting an appropriate discharge time, the particle size variation can be controlled to a predetermined value or less.

Alternatively, aluminum may be formed on the substrate 101 as the base structure of the metal catalyst particles. Aluminum tends to form an island-shaped structure having a uniform particle size at the initial stage of film formation. By appropriately adjusting the film formation speed, the film formation time, and the like, an island structure having a desired particle size can be easily formed on the substrate. If the metal catalyst particles are formed on such an aluminum base structure, the metal catalyst particles are aggregated only on the aluminum base structure when the metal catalyst particles are heated, and agglomerate beyond the aluminum base structure. Nothing will happen. Therefore, metal catalyst particles having a particle size larger than that of the aluminum base structure are not generated, and carbon nanotubes having a desired property can be easily formed.

In addition, since aluminum is more easily oxidized than cobalt and iron constituting the metal catalyst particles, aluminum is preferentially oxidized in the process of growing carbon nanotubes, thereby preventing deactivation due to oxidation of the metal catalyst particles, It is possible to prevent defects in the growth of carbon nanotubes.

Note that the base structure is not limited to the above-described aluminum as long as it is a substance that can form an island-shaped structure on the substrate. Moreover, you may use substances other than aluminum in order to prevent the oxidation of a metal catalyst particle.

Alternatively, particles (aggregation-inhibiting particles) for preventing aggregation of the metal catalyst particles may be formed on the substrate 101. Alternatively, as the metal catalyst particles, an alloy of a catalyst substance that acts as a catalyst for promoting carbon nanotube growth and an aggregation inhibitor that prevents aggregation of the metal catalyst particles may be used. As described above, at least one metal selected from the group consisting of cobalt, nickel, iron and the like can be used as the catalyst substance.

As the aggregation-inhibiting particles and the aggregation-inhibiting substance, a refractory metal having a melting point of 1500 ° C. or higher can be used. For example, molybdenum (melting point 2620 ° C.), tungsten (melting point 3400 ° C.), tantalum (melting point 3027 ° C.), rhenium (melting point 3100 ° C.), osmium (melting point 3045 ° C.), iridium (melting point 2454 ° C.), platinum (melting point 1772 ° C.) Hafnium (melting point 2222 ° C), rhodium (melting point 1966 ° C), palladium (melting point 1555 ° C), ruthenium (melting point 2500 ° C), technetium (melting point 2172 ° C), niobium (melting point 2415 ° C), zirconium (melting point 1852 ° C), At least one refractory metal selected from the group consisting of yttrium (1520 ° C.) can be used.

Furthermore, in addition to the metal catalyst particles, obstacle particles may be disposed on the substrate 101 in order to adjust the deposition density of the metal catalyst particles on the substrate 101 and thereby control the growth density of the carbon nanotubes. As such obstacle particles, inorganic compound particles are preferable. Among the inorganic compounds, it is more preferable to use a high-melting-point inorganic compound that hardly causes a chemical reaction with the catalyst substance constituting the metal catalyst particles. For example, it is preferable to use at least one oxide selected from the group consisting of aluminum oxide, magnesium oxide, titanium oxide, and silicon oxide. The particle diameter of the obstacle particles is not particularly limited and is appropriately selected according to the desired precipitation density of the metal catalyst particles, but is preferably in the range of 2 nm to 50 nm.

A second method for forming metal catalyst particles having a predetermined particle diameter on the substrate 101 is a dip coating method. The dip coating method is a method in which the substrate is immersed in a solution containing metal ions and then pulled up, and the solvent is removed to deposit metal catalyst particles on the substrate.
As a solution used for the dip coating method, a solution in which a salt (such as acetate, nitrate, chloride) containing a metal to be precipitated is dissolved in a solvent such as ethanol, acetone, water, or the like can be used.
When the metal catalyst particles are formed on the substrate 101 using the dip coating method, the particle size of the metal catalyst particles can be controlled by the metal ion concentration. The lower the metal ion concentration, the smaller the particle size of the metal catalyst particles, and the higher the metal ion concentration, the larger the particle size. In addition to the metal ion concentration, the particle size can be controlled by adjusting the pulling speed of the substrate 101.
The pulling speed of the substrate 101 also affects the particle size distribution (variation). In order to reduce the variation in the particle diameter, it is effective to reduce the pulling rate of the substrate 101. Therefore, the pulling speed of the substrate 101 is adjusted so that the particle size and, if necessary, the variation in the particle size become a predetermined value.
In addition to the magnetron sputtering method and the dip coating method described above, it is possible to form metal catalyst particles having a desired particle diameter by shortening the deposition time in a vacuum film forming process such as vacuum deposition.

<Reduction process>
The surface of the metal catalyst particles formed on the substrate 101 is often oxidized, and it is difficult to grow carbon nanotubes uniformly as it is. Therefore, metal catalyst particles are reduced before carbon nanotube growth.
The surface of the metal catalyst particles is performed by storing the substrate on which the metal catalyst particles are formed in a reaction furnace and heating the metal fine particles to a predetermined reduction reaction temperature with the inside of the reaction furnace as a reducing atmosphere. In order to create a reducing atmosphere in the reaction furnace, a reducing gas such as hydrogen gas, diluted hydrogen gas, or carbon monoxide gas is introduced into the reaction furnace. Moreover, when it is set as the reducing atmosphere containing hydrogen gas, it is preferable that hydrogen concentration is 1 volume% or more. Further, the pressure in the reactor is not particularly limited, and can be appropriately set within a range of 0.1 Pa to 10 ⁵ Pa.
If the reduction temperature is 300 ° C. or higher, the surface of the metal catalyst particles can be reduced. Moreover, it is preferable that a reduction temperature is 400 degrees C or less from a viewpoint of preventing aggregation of a metal catalyst particle. That is, when the reduction temperature is set to 300 ° C. or more and 400 ° C. or less, the reduction reaction can be sufficiently advanced without aggregating the metal catalyst particles, and the carbon nanotube aggregate having a desired property can be easily formed. .
The holding time at the reduction temperature in the reduction step is preferably 480 seconds or more, and more preferably 600 seconds or more. If the holding time is too short, the surface of the metal catalyst particles is not sufficiently reduced, and as a result, the growth of the carbon nanotubes may be insufficient.

<CVD process>
After reducing the surface of the metal catalyst particles by the reduction step, carbon nanotubes are grown on the substrate 101 using this as a catalyst. It is preferable that the reduction process and the carbon nanotube growth process are continuously performed in the same apparatus. This is because when the metal catalyst particles whose surfaces have been reduced are exposed to an oxidizing atmosphere such as air, the surfaces of the metal catalyst particles are oxidized again, the catalytic activity is lowered, and it becomes difficult to grow desired carbon nanotubes.
In order to grow the carbon nanotubes on the metal catalyst particles, the metal catalyst particles are heated to a predetermined reaction temperature and brought into contact with the organic compound vapor.

Here, FIG. 5 is a diagram showing a carbon nanotube aggregate production apparatus that can be suitably used in the carbon nanotube aggregate production process of the present embodiment.
The manufacturing apparatus shown in FIG. 5 includes a reaction furnace 11, a raw material container 21 that contains the raw material supplied to the reaction furnace 11, and a reducing gas that supplies a reducing gas and an inert gas to the reaction furnace 11 and the raw material container 21. A supply unit 1 and an inert gas supply unit 2, an exhaust device 19 connected to the reaction furnace 11, and a control device 17 that controls the operating state of the reaction furnace 11 are provided.

In the center of the reaction furnace 11, a furnace core tube 14 capable of evacuation and gas replacement is disposed. A radiant heater 12 having a peak of the energy spectral distribution in the wavelength range of 1.0 μm to 1.7 μm is provided outside the furnace core tube 14. The substrate 101 on the substrate holder 15 disposed inside the core tube 14 can be uniformly and rapidly heated by the radiation heater 12. The radiant heater 12 is preferably an infrared furnace. The temperature of the substrate 101 is measured by the thermometer 18, and the power supplied to the radiation heater 12 is controlled by the control device 17 so as to be a predetermined temperature programmed in advance.

A reducing gas supply unit 1 and an inert gas supply unit 2 are provided outside the reaction furnace 11, and the gas supplied from each is supplied to the manufacturing apparatus via the valve 3 and the valve 4. Each gas flow rate is controlled to be constant by a flow rate control mechanism 1a, 2a provided with a mass flow controller or the like.

The reducing gas and the inert gas are supplied into the raw material container 21 through the valve 5. The raw material container 21 is configured to be heated and held at a predetermined temperature by the heater 8 and the water bath 9, and can generate the vapor of the raw material 10 accommodated therein at a constant vapor pressure. The raw material vapor generated inside the raw material container 21 can independently control the supply amounts of reducing gas, inert gas, and organic compound vapor supplied through the valve 5.
Each of the gases supplied to the core tube 14 is used for the reduction reaction of the metal catalyst particles on the substrate 101 disposed in the core tube 14 or the carbon nanotube growth reaction on the metal catalyst particles. The contained exhaust gas is discharged out of the system through an exclusion device 20 such as a cold trap and an exhaust device 19 such as an oil rotary pump.
Note that the manufacturing apparatus having the configuration shown in FIG. 5 can continuously perform a reduction process for reducing the surface of the metal catalyst particles and a CVD process for growing carbon nanotubes.

Next, the CVD process using the above manufacturing apparatus will be specifically described.
After reducing the surface of the metal catalyst particles on the substrate 101 in the previous step, the metal catalyst particles are heated to a predetermined reaction temperature. The reaction temperature varies depending on the type of catalyst and the type of organic compound used as a raw material. For example, when ethanol is used as a raw material, it is about 600 ° C. to 1000 ° C., and when methane is used as a raw material, it is about 700 ° C. to 1200 ° C. It is preferable.
Here, when the reaction temperature is lower than 500 ° C., the growth of amorphous carbon becomes dominant, resulting in a problem that the yield of carbon nanotubes is lowered. On the other hand, if the reaction temperature is set to a temperature higher than 1300 ° C., a material that can withstand high temperatures must be used as the constituent material of the substrate 101 and the reaction furnace 11, which increases the restrictions on the apparatus. Therefore, the reaction temperature is preferably 500 ° C. or higher, more preferably 1300 ° C. or lower.
The atmosphere during the temperature rise may be a reducing atmosphere or an inert gas atmosphere such as a rare gas.

If the metal catalyst particles are held at a temperature exceeding 450 ° C. before the carbon nanotube starts growing, the metal catalyst particles start to aggregate regardless of the atmosphere. Therefore, in the CVD process, it is necessary to rapidly raise the metal catalyst particles on the substrate 101 to the reaction temperature. Therefore, in the manufacturing apparatus shown in FIG. 5, the radiant heater 12 having the peak of the energy spectral distribution in the wavelength range of 1.0 μm to 1.7 μm is provided as a means for obtaining a necessary temperature increase rate. By using this radiation heater 12, it becomes possible to rapidly heat the metal catalyst particles to be heated and the substrate 101 on which the metal catalyst particles are formed.

Since the metal catalyst particles have a very small particle size, it is difficult to control the temperature so that a desired temperature increase rate can be obtained by directly measuring the temperature. Therefore, a control device is provided so that a predetermined temperature increase rate can be obtained by measuring the temperature of the surface of the substrate 101 on which the metal catalyst particles are formed (the surface having the metal catalyst particles) with a thermometer 18 equipped with a thermocouple or the like. The radiant heater 12 is controlled by 17. Since the metal catalyst particles are fine particles, the heat capacity is very small, and since the metal catalyst particles are metal, the heat conductivity is high. Therefore, the temperature of the metal catalyst particles can be regarded as almost the same as the surface temperature of the substrate 101. Therefore, the temperature of the metal catalyst particles can be controlled by the above control method.
Even when the metal catalyst particles are formed on both surfaces of the substrate 101, it is sufficient to measure the temperature of one surface of the substrate 101 if the temperatures of both surfaces of the substrate 101 can be regarded as substantially equal.

When the metal catalyst particles are heated to a predetermined reaction temperature using the above heating means, an organic compound vapor serving as a carbon nanotube raw material is introduced into the core tube 14 of the reaction furnace 11.
The organic compound used as a raw material for the carbon nanotube is at least one compound selected from the group consisting of methane, ethane, propane, butane, ethylene, and acetylene, which are linear hydrocarbons, or a linear monohydric alcohol At least one compound selected from the group consisting of methanol, ethanol and propanol, or at least one compound selected from the group consisting of aromatic hydrocarbons such as benzene, naphthalene, anthracene, and derivatives thereof Compounds can be used. In addition to these compounds, organic compounds capable of generating carbon nanotubes on metal catalyst particles can be used as raw materials.

When the organic compound vapor is introduced into the reaction furnace 11, if the temperature of the metal catalyst particles reaches a predetermined reaction temperature, the carbon nanotubes immediately start to grow. After carbon nanotubes begin to grow, the surface of the metal catalyst particles is covered with raw material compounds, carbon, and reaction intermediates, so that even if the reaction temperature exceeds 450 ° C, the aggregation of the metal catalyst particles further proceeds. Rather, the particle size at the start of growth is maintained. Therefore, the carbon nanotubes having the number of graphene sheet layers corresponding to the particle diameter of the metal catalyst particles at the start of growth grow continuously.

When carbon nanotubes having a desired length are grown on the metal catalyst particles by the above procedure, the supply of the organic compound vapor is stopped, and the carbon nanotubes are formed on the surface after the reaction furnace 11 is returned to room temperature. The substrate 101 is taken out.
As described above, the optical element 100 having the carbon nanotube aggregate formed on the surface of the substrate 101 can be manufactured.

In the case of manufacturing the optical element 100A shown in FIG. 3, a metal film forming step for forming the metal film 103 on the substrate 101 is provided prior to the catalyst particle forming step in the manufacturing process of the optical element 100. Good. In the metal film forming step, for example, a chromium film is formed with a predetermined film thickness on the substrate 101 by magnetron sputtering. The catalyst particle formation process, the reduction process, and the CVD process after the metal film formation process are the same as the manufacturing process of the optical element 100 described above.

(Exposure equipment)
The optical element according to the above-described embodiment can be suitably used as a constituent member of the exposure apparatus. Hereinafter, an exposure apparatus according to an embodiment will be described in detail with reference to FIG.

FIG. 6 is a view showing an exposure apparatus to which the optical element can be applied.
The exposure apparatus EX is a scanning exposure apparatus (so-called scanning stepper) that exposes the image of the pattern PA formed on the mask M onto the substrate P while moving the mask M and the substrate P synchronously in the scanning direction. The exposure apparatus EX includes a mask stage MST that is movable while holding the mask M, a substrate stage PST that is movable while holding the substrate P, and illumination optics that illuminates the mask M held on the mask stage MST with the exposure light EL. System 230 (illumination device), photodetection device 260 provided in illumination optical system 230, projection optical system PL that projects an image of pattern PA of mask M illuminated by exposure light EL onto substrate P, and overall exposure apparatus EX A control device 207 and the like for controlling the operation.
Here, the substrate includes a substrate in which a photosensitive material (resist) is coated on a base material such as a semiconductor wafer, and the mask includes a reticle on which a device pattern to be reduced and projected is formed on the substrate. In this embodiment, a transmissive mask is used as a mask, but a reflective mask can also be used.
In the following description, the synchronous movement direction (scanning direction) of the mask M and the substrate P in the horizontal plane is the Y-axis direction, the direction orthogonal to the Y-axis direction in the horizontal plane is the X-axis direction (non-scanning direction), the X-axis, and A direction perpendicular to the Y-axis direction and coincident with the optical axis AX of the projection optical system PL is defined as a Z-axis direction. In addition, the rotation (inclination) directions around the X, Y, and Z axes are the θX, θY, and θZ directions, respectively.

The exposure apparatus EX is an immersion exposure apparatus to which an immersion method is applied in order to improve the resolution by substantially shortening the exposure wavelength and substantially increase the depth of focus. A liquid immersion mechanism 210 that fills the optical path space K of the exposure light EL on the image plane side with the liquid LQ is provided. The exposure apparatus EX fills the optical path space K of the exposure light EL with the liquid LQ by using the liquid immersion mechanism 210 while exposing at least the pattern image of the mask M to the substrate P. The exposure apparatus EX irradiates the substrate P with the exposure light EL that has passed through the mask M via the projection optical system PL and the liquid LQ filled in the optical path space K, whereby the image of the pattern PA of the mask M is formed on the substrate. P is exposed.
Further, in the exposure apparatus EX of the present embodiment, the liquid LQ filled in the optical path space K is larger than the projection area AR in a part of the area on the substrate P including the projection area AR of the projection optical system PL. A local liquid immersion method is adopted in which the liquid immersion region LR of the liquid LQ smaller than P is locally formed. In the present embodiment, pure water is used as the liquid LQ.

The illumination optical system 230 includes an optical system housing 230H as a housing for housing various optical devices, a light source device 231 that emits exposure light EL as a laser beam, and a cross section of exposure light (laser beam) EL emitted from the light source device 231. A beam shaping optical system 232 for shaping the shape, an energy adjuster 233 for adjusting the energy of the exposure light EL that passes through, and a secondary light source by the exposure light EL that is emitted from the energy adjuster 233 and whose optical path is bent by the mirror 234 An optical integrator 235 including a fly-eye lens and the like that is formed to make the illuminance of the exposure light EL uniform on the mask M, an aperture stop (σ stop) 236 provided on the light exit surface of the optical integrator 235, a relay lens system 238 The first and second relay lenses 238A, 238B constituting Blind apparatus 250 for setting the irradiation area (illumination area) IA of the exposure light EL on the mask M, the condenser lens 240, a photodetector 260, and the like.
In the optical system housing 230H, a beam shaping optical system 232, an energy adjuster 233, a mirror 234, an optical integrator 235, an aperture stop 236, a relay lens system 238, a blind device 250, a condenser lens 240, and the like are housed.

The light source device 231 includes an excimer laser light source. As exposure light (laser beam) EL emitted from the light source device 231, far ultraviolet light (DUV light) such as KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), and F2 laser light (wavelength) Vacuum ultraviolet light (VUV light) such as 157 nm) is used. In the present embodiment, an ArF excimer laser light source is used as the light source device 231, and ArF excimer laser light is used as the exposure light EL.
The exposure light EL (laser beam) emitted from the light source device 231 is not only KrF excimer laser light, ArF excimer laser light, and F2 laser light, but also bright lines (g line, h line) emitted from a mercury lamp. , I-line) or the like.

The exposure light (laser beam) EL emitted from the light source device 231 enters the beam shaping optical system 232.
The beam shaping optical system 232 shapes the cross-sectional shape of the exposure light EL so that the exposure light EL emitted from the light source device 231 efficiently enters the optical integrator 235. For example, a cylindrical lens or a beam expander is used. Etc.

The exposure light EL that has passed through the beam shaping optical system 232 enters the energy adjuster 233.
The energy adjuster 233 adjusts the energy of the exposure light EL emitted from the energy adjuster 233. The energy adjuster 233 includes a plurality of ND filters F0 to F2 disposed on the rotatable revolver Rv and having different transmittances for the exposure light EL. More specifically, the revolver Rv is configured to be rotatable about the rotation axis O, and the revolver Rv includes a plurality of ND filters F0, F1, and F2 having different transmittances (dimming rates) at equal angular intervals in the circumferential direction. Is arranged.
The energy adjuster 233 rotates the revolver Rv to switch the ND filters F0 to F2 arranged on the optical path of the exposure light EL, thereby changing the energy of the exposure light EL emitted from the energy adjuster 233 in a plurality of stages. Can be adjusted. The revolver Rv may be formed with a through hole through which the exposure light EL passes, and may have two or less or four or more ND filters.

The exposure light EL emitted from the energy adjuster 233 is bent in its optical path by the mirror 234 and is incident on the optical integrator 235.
The optical integrator 235 makes the illuminance of the exposure light EL on the mask M uniform, and forms a large number of secondary light sources from the exposure light EL incident through the mirror 234. The exposure light EL that has been emitted from the optical integrator 235 and passed through the aperture stop 236 is branched in two directions by a beam splitter 237 that has low reflectance and high transmittance.

The exposure light EL that has passed through the beam splitter 237 passes through the blind device 250 via the first relay lens 238A.
The blind device 250 is provided on the optical path of the exposure light EL, and determines an irradiation area (illumination area) IA of the exposure light EL on the mask M and an irradiation area (projection area) AR of the exposure light EL on the substrate P. It can be adjusted. The blind device 250 is disposed in the vicinity of the conjugate plane with respect to the plane of the pattern PA of the mask M.
The blind device 250 is configured by combining a plurality of movable blades 252 and includes a plurality of linear motors 255 that drive the plurality of movable blades 252. These movable blades 252 form an opening 250K for setting an irradiation area (illumination area) IA of the exposure light EL on the mask M on the optical path of the exposure light EL. The opening 250K has a rectangular shape, and the irradiation area (illumination area) IA of the exposure light EL on the mask M and the irradiation area (projection area) AR of the exposure light EL on the substrate P are set to be rectangular. By setting the irradiation area (illumination area) IA of the exposure light EL on the mask M, the irradiation area (projection area) AR of the exposure light EL on the substrate P is also set.

The control device 207 adjusts the size of the opening 250 </ b> K by driving the movable blade 252 via the linear motor 255 of the blind device 250. By adjusting the size of the opening 250K of the blind device 250, the size of the irradiation area (illumination area) IA of the exposure light EL on the mask M and the projection area (irradiation area) of the exposure light EL on the substrate P The size of AR can be adjusted. In addition, the control device 207 drives the movable blade 252 using the linear motor 255 of the blind device 250, so that the control device 207 in the direction corresponding to each of the scanning direction (Y-axis direction) and the non-scanning direction (X-axis direction). The width and position of the opening 250K can be adjusted.
In this way, the control device 207 controls the irradiation area (illumination area) IA on the mask M of the exposure light EL in the scanning direction (Y-axis direction) and the non-scanning direction (X-axis direction), and the substrate P. The size of the irradiation area (projection area) AR can be adjusted.

The exposure light EL that has passed through the blind device 250 illuminates the rectangular illumination area IA on the mask M held on the mask stage MST with a uniform illuminance distribution via the second relay lens 238B and the condenser lens 240. .
On the other hand, of the exposure light EL that has entered the beam splitter 237, the exposure light EL reflected by the beam splitter 237 is guided to the light detection device 260 and used for energy measurement. The light detection device 260 includes a condenser lens 241, a measuring instrument (measuring device) 242, an ND filter 243, a sensor housing 260H that accommodates these, and the like.
The exposure light EL reflected by the beam splitter 237 is collected by the condenser lens 241, then enters the measuring instrument 242 (measuring device) via the ND filter 243, and is measured by the measuring instrument 242. The measuring instrument 242 measures the energy of the exposure light EL, and is composed of, for example, a photoelectric conversion element. The measurement signal of the measuring instrument 242 is output to the control device 207.

The mask stage MST holds the mask M on the mask table 203 and is driven by a mask stage driving device 203D including an actuator such as a linear motor, so that the mask table 203 is moved on the base member 203B by the X axis, Y axis, and It can move in the θZ direction.
Position information of the mask table 203 (and thus the mask M) is measured by the laser interferometer 203L. The laser interferometer 203L measures the position information of the mask table 203 using a reflecting mirror 203K provided on the mask table 203. The control device 207 drives the mask stage driving device 203D based on the measurement result of the laser interferometer 203L, and controls the position of the mask M held on the mask table 203.

The projection optical system PL projects an image of the pattern PA of the mask M onto the substrate P at a predetermined projection magnification, and has a plurality of optical elements, and these optical elements are held by a lens barrel PK. Yes. The projection optical system PL of the present embodiment is a reduction system whose projection magnification is, for example, 1/4, 1/5, 1/8 or the like.
Note that the projection optical system PL may be either an equal magnification system or an enlargement system. The projection optical system PL may be any of a refractive system that does not include a reflective optical element, a reflective system that does not include a refractive optical element, and a catadioptric system that includes a reflective optical element and a refractive optical element. Further, the projection optical system PL may form either an inverted image or an erect image.
Of the plurality of optical elements of the projection optical system PL, only the final optical element FL closest to the image plane of the projection optical system PL is in contact with the liquid LQ in the optical path space K.

The substrate stage PST can move the substrate table 204 on the base member 205 in the direction of 6 degrees of freedom while holding the substrate P on the substrate table 204.
The substrate table 204 has six degrees of freedom in the X-axis, Y-axis, Z-axis, θX, θY, and θZ directions while holding the substrate P by driving a substrate stage driving device 204D including an actuator such as a linear motor. It can move in the direction.
The position information of the substrate table 204 (and thus the substrate P) is measured by the laser interferometer 204L. The laser interferometer 204L uses the reflecting mirror 204K provided on the substrate table 204 to measure position information regarding the X axis, the Y axis, and the θZ direction of the substrate table 204. Further, surface position information (position information regarding the Z-axis, θX, and θY directions) of the surface of the substrate P held on the substrate table 204 is detected by a focus / leveling detection system (not shown). The control device 207 drives the substrate stage driving device 204D based on the measurement result of the laser interferometer 204L and the detection result of the focus / leveling detection system, and controls the position of the substrate P held on the substrate table 204.

The liquid immersion mechanism 210 is provided at a position facing the final optical element FL of the projection optical system PL through which the exposure light EL passes, and the substrate P held on the substrate table 204, and located at a position facing the final optical element FL. The space K is filled with the liquid LQ. The liquid LQ that fills the optical path space K contacts the lower surface FLA of the final optical element FL, and the exposure light EL passes through the lower surface FLA of the final optical element FL.
The liquid immersion mechanism 210 is provided in the vicinity of the optical path space K, and includes a nozzle member 225, a supply pipe 213, and a nozzle member 225 having a supply port for supplying the liquid LQ to the optical path space K and a recovery port for recovering the liquid LQ. A liquid supply device 211 that supplies the liquid LQ through the supply port, a recovery port of the nozzle member 225, a liquid recovery device 221 that recovers the liquid LQ through the recovery pipe 223, and the like are provided.
Inside the nozzle member 225, a flow path connecting the supply port and the supply pipe 213 and a flow path connecting the recovery port and the recovery pipe 223 are formed.
The operations of the liquid supply device 211 and the liquid recovery device 221 are controlled by the control device 207. The liquid supply device 211 can deliver a clean and temperature-adjusted liquid LQ, and the liquid recovery device 221 including a vacuum system and the like can recover the liquid LQ. The control device 207 controls the liquid immersion mechanism 210 to perform the liquid supply operation by the liquid supply device 211 and the liquid recovery operation by the liquid recovery device 221 in parallel, so that the optical path space K is filled with the liquid LQ, and the substrate An immersion region LR of the liquid LQ is locally formed in a partial region on P.

In the exposure apparatus EX having the above configuration, the optical elements 100 and 100A described above can be applied to a plurality of constituent members.
Specifically, the optical element 100 or the optical element 100A can be used as the ND filter 243 that attenuates the exposure light EL branched from the illumination optical system 230. By configuring the ND filter 243 with the optical elements 100 and 100A, reflection of light incident on the ND filter 243 from the condenser lens 241 can be suppressed to an extremely low level. Thereby, it is possible to prevent the light reflected by the ND filter 243 from entering the measuring instrument 242, and to improve the measurement accuracy of the exposure light EL.

The optical elements 100 and 100A can be used as light absorbing elements that absorb light scattered from the optical path of the exposure light EL to the surroundings. For example, the optical element 100 or the optical element 100A can be installed on the inner wall 230w of the optical system housing 230H, the inner wall 260w of the sensor housing 260H, and the inner wall PKw of the lens barrel PK.
Thus, by installing the optical elements 100 and 100A on the inner wall of the housing or the lens barrel, the scattered light from the optical path can be absorbed by the optical elements 100 and 100A. Thereby, it is possible to prevent the scattered light from being reflected by the inner wall of the housing or the lens barrel and returning to the optical path side.

As the optical element 100 installed on the inner wall 230w of the optical system housing 230H, the inner wall 260w of the sensor housing 260H, and the inner wall PKw of the lens barrel PK, for example, on the substrate 101 such as quartz glass, the surface of the substrate 101 is formed by the CVD method. The CNT layer 102 made of carbon nanotubes oriented substantially vertically can be used, and the substrate 101 on which the CNT layer 102 is formed can be used by being disposed on the inner walls 230w, 260w, and PKw. it can.

In addition to the above, it can be used in the following form.
First, a CNT layer 102 made of carbon nanotubes oriented substantially perpendicular to the substrate surface is formed by CVD on a substrate 101 that can withstand a CVD reaction temperature such as quartz glass.
Next, the CNT layer 102 is separated from the substrate 101. As a method for separation, a method of separating the CNT layer 102 and the substrate 101 by immersing the substrate 101 on which the CNT layer 102 is formed in warm water of about 60 ° C. can be used. A method of separating only the carbon nanotube aggregate (CNT layer 102) in the vertically aligned state to obtain a self-supporting film has been proposed by Maruyama (see Japanese Patent Application Laid-Open No. 2007-182342).
Then, by fixing the separated CNT film (CNT layer 102) to the inner wall 230w of the optical system housing 230H, the inner wall 260w of the sensor housing 260H, the inner wall PKw of the lens barrel PK, and the like using an adhesive, A configuration including a light absorbing element can be obtained. As the adhesive used for bonding the CNT film and the wall material, an adhesive that generates little volatile gas even when irradiated with ultraviolet rays can be used.

Furthermore, the optical elements 100 and 100A can be applied to some or all of the ND filters F0, F1, and F2 constituting the energy adjuster 233. In the optical element 100, the transmittance can be adjusted by changing the length or area density of the carbon nanotubes in the CNT layer 102. In the optical element 100A, the transmittance is also adjusted by the thickness of the metal film 103. Can do. Therefore, the energy adjuster 233 can be suitably used for a plurality of ND filters F0 to F2 having different transmittances, and a low reflection energy adjuster 233 can be configured.

Note that when light having a wavelength shorter than 250 nm is used as exposure light, the intensity of the exposure light is reduced by absorption by oxygen, so that all the optical paths are purged with an inert gas such as nitrogen. In the exposure apparatus EX of the present embodiment, the optical elements 100 and 100A are provided on the optical path or at a position facing the optical path. The optical elements 100 and 100A are arranged so that at least the CNT layer 102 is in an inert gas atmosphere. Can be done. Thereby, oxygen and the like in the atmosphere can be reduced, so that it is possible to prevent the carbon nanotubes from being easily damaged or decomposed due to the presence of oxygen or the like when the CNT layer 102 is irradiated with light.

Further, the CNT film formed by separating the CNT layer 102 formed on the optical elements 100 and 100A or the substrate 101 of the previous embodiment may be used as another constituent member of the exposure apparatus EX. For example, when the illumination optical system 230 of the exposure apparatus EX and the light source device 231 are installed at a distance from each other, and a light routing unit for routing light from the light source device 231 to the illumination optical system 230 is provided, The optical elements 100 and 100A and the CNT film may be used for the casing and optical system of the light routing unit. Alternatively, the light source device 231 can be used for a housing and an optical system.

As the substrate P in the above-described embodiment, not only a glass substrate for a display device but also a semiconductor wafer for manufacturing a semiconductor device, a ceramic wafer for a thin film magnetic head, or an original mask (reticle) used in an exposure apparatus ( Synthetic quartz, silicon wafer) or the like is applied.

As the exposure apparatus EX, a step-and-scan type scanning exposure apparatus (scanning stepper) that scans and exposes the substrate P with the exposure light EL through the pattern of the mask M by moving the mask M and the substrate P synchronously. In addition, the pattern of the mask M is collectively exposed while the mask M and the substrate P are stationary, and is applied to a step-and-repeat type projection exposure apparatus (stepper) that sequentially moves the substrate P stepwise. Can do.

Also, the present invention can be applied to a proximity type exposure apparatus, a mirror projection aligner, and the like as the exposure apparatus EX.

The present invention also relates to a twin-stage type exposure having a plurality of substrate stages as disclosed in US Pat. No. 6,341,007, US Pat. No. 6,208,407, US Pat. No. 6,262,796, and the like. It can also be applied to devices.

Further, the present invention relates to a substrate stage for holding a substrate as disclosed in US Pat. No. 6,897,963, European Patent Application No. 1713113, etc., and a reference mark without holding the substrate. The present invention can also be applied to an exposure apparatus that includes a formed reference member and / or a measurement stage on which various photoelectric sensors are mounted. An exposure apparatus including a plurality of substrate stages and measurement stages can be employed.

The type of the exposure apparatus EX is not limited to an exposure apparatus for manufacturing a liquid crystal display element or a display, but an exposure apparatus for manufacturing a semiconductor element that exposes a semiconductor element pattern on a substrate P, a thin film magnetic head, an image sensor (CCD) In addition, the present invention can be widely applied to an exposure apparatus for manufacturing a micromachine, MEMS, DNA chip, reticle, mask, or the like.

The exposure apparatus EX of the above-described embodiment is manufactured by assembling various subsystems including each component so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus can be manufactured in a clean room in which temperature, cleanliness, etc. are controlled.

In another embodiment, a confocal microscope such as that disclosed in Japanese Patent Application Laid-Open No. 11-183806 is used as the ND filter with the optical element including the region where the carbon nanotube aggregate (CNT) is formed. It can be applied to a light control device. In this case, as a configuration example of the ND filter, a type in which the density changes in the circumferential direction can be adopted. For example, the amount of transmitted light can be selectively adjusted by dividing a plurality of regions in the circumferential direction and arranging ND filters having different CNT concentrations (CNT density or CNT length) for each region. . Or it can be set as the ND filter which changes a transmitted light quantity continuously by changing CNT density | concentration continuously in the circumferential direction. In this example, the substrate is on the beam expander side, the CNT film is on the laser light source side, and the CNT fibers are facing the laser light source side. As described above, by using the light absorption film using CNT for the ND filter of the microscope, the light amount can be adjusted substantially without reflection. As a result, in a microscope in which many optical members are arranged in the optical path, high-resolution observation with reduced noise becomes possible.

In another embodiment, the optical element including a region where a carbon nanotube aggregate (CNT) is formed may be applied as an ND filter to a microscope other than the confocal microscope, such as a fluorescence microscope or a phase contrast microscope. it can. In this case, for example, a fluorescence microscope is expected to detect weak light from a biological sample with high sensitivity.

In still another embodiment, the optical element including the region where the carbon nanotube aggregate (CNT) is formed may be used as a light absorption film on the inner wall of the housing of the optical path of the microscope (from the light source to the objective lens). it can. Light absorption film using CNT has low reflectivity for light up to a high incident angle and extremely low wavelength dependence (low reflectivity from ultraviolet to infrared region), so it efficiently absorbs stray light and absorbs noise. Can be reduced.

In still another embodiment, the optical element including a region where a carbon nanotube aggregate (CNT) is formed can be used as a light absorption film on an inner wall of a housing of an optical system of an inspection apparatus such as a microdevice, As the control film formation, it can be applied to an inspection device such as a micro device or a light amount adjusting device of a device that performs measurement and observation by irradiating a sample with light.

As shown in FIG. 7, a device such as a semiconductor device, a display device, or an electronic device is manufactured in step 301 for designing the function / performance of the device, in step 302 for manufacturing a mask M based on this design step, and on a substrate P. Step 303, in accordance with the above-described embodiment, the substrate P is exposed with the exposure light EL from the pattern of the mask M to transfer the pattern to the substrate P, and the substrate P to which the pattern is transferred is developed to form a pattern. Device assembly including processing steps for processing the substrate P via the transfer pattern layer, such as a substrate processing step 304 including a development step for forming a transfer pattern layer having a corresponding shape on the substrate P, a dicing step, a bonding step, and a packaging step. It is manufactured through step 305, inspection step 306, and the like.

It should be noted that the requirements of the above-described embodiments and modifications can be combined as appropriate. Some components may not be used. In addition, as long as it is permitted by law, the disclosure of all published publications and US patents related to the exposure apparatus and the like cited in the above-described embodiments and modifications are incorporated herein by reference.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples.

In this example, an optical element according to the present invention was manufactured by using a quartz glass substrate, forming an aggregate of carbon nanotubes using aluminum as a base structure and iron-cobalt as a catalyst.

<Catalyst particle formation>
First, a surface-polished quartz glass substrate (20 mm × 20 mm × 0.5 mmt) was prepared. The quartz glass substrate was sufficiently cleaned by ultrasonic cleaning in alcohol and cleaning by ultraviolet irradiation.
After cleaning, the quartz glass substrate was placed in a film forming chamber of a magnetron sputtering apparatus, and the inside of the film forming chamber was evacuated to a high vacuum of 1 × 10 ⁻⁴ Pa or less.
Next, argon gas was introduced into the film formation chamber, and the pressure was adjusted to 2.1 Pa. Thereafter, plasma is generated by applying a high frequency of 13.56 MHz to the cathode to which the aluminum target is attached, and aluminum is converted into a film thickness of 5 nm in a 15 mm × 15 mm region of the quartz glass substrate. A film was formed.
Thereafter, a high frequency is applied to the cathode to which the iron target is attached to generate plasma, and iron is converted into a film thickness of 1 nm in a region on the quartz glass substrate on which the aluminum film has been formed. Filmed.
Thereafter, a high frequency is applied to the cathode to which the cobalt target is attached to generate plasma, so that cobalt is converted into a film thickness of 1 nm in a region on the quartz glass substrate on which aluminum and iron are formed. A film was formed.

Here, the sputtering film thickness in the catalyst particle forming step will be described.
In the catalyst particle formation process, the thickness of each layer formed by the sputtering method is very thin, so it is not actually a continuous film. It becomes a state. Therefore, the sputter film thickness does not match the actual thickness and particle diameter of aluminum, iron, and cobalt, but is a parameter necessary for performing sputtering while controlling the particle diameter.

The desired sputter film thickness can be set by the following procedures (1) to (4).
(1) Sputter deposition is performed on a spare quartz glass substrate for 100 minutes.
(2) The thickness of the thick continuous film obtained by the film formation for 100 minutes is accurately measured by the step measuring device. Although the film thickness varies depending on the film formation conditions and the target type, in this example, the film thickness was in the range of 90 to 120 nm.
(3) Deposition rate is calculated by the equation of deposition rate (nm / s) = film thickness (nm) / 3600 (s).
(4) With respect to the quartz glass substrate prepared for forming the carbon nanotube aggregate, the desired sputtering film thickness (nm) = deposition time (s) × deposition rate (nm / s) was calculated. The film formation time is set as a sputtering condition.
The desired sputter film thickness is derived in advance as a film forming condition suitable for the growth of carbon nanotubes. For example, a plurality of samples having different film thicknesses are prepared for each layer of aluminum, iron, and cobalt, and a carbon nanotube growth step is performed for each sample. Based on these results, the optimum film formation conditions can be set as the target value of the sputter film thickness.

<Reduction of catalyst particles>
The quartz glass substrate on which the catalyst particles were formed was stored in the core tube 14 of the manufacturing apparatus shown in FIG. At this time, in order to measure the temperature of the quartz glass substrate, a thermometer 18 was brought into contact with the upper surface of the quartz glass substrate and fixed.
Next, after the reactor 11 is sealed and the inside is evacuated to 0.4 Pa, the valve 3 and the valve 6 are opened and a mixed gas of argon and hydrogen (H ₂ : Ar = 3%: 97%) is supplied. The internal pressure of the core tube 14 was set to 70 kPa. The energization of the radiant heater 12 is started while maintaining the internal pressure of the furnace tube 14, and the radiant heater 12 (infrared furnace, manufactured by ULVAC-RIKO Inc., RHL-) is controlled by the controller 17 so that the substrate temperature rises at 5 ° C./sec. The power supplied to P610) was controlled.
When the substrate temperature reached 400 ° C., this state was maintained for 30 minutes to sufficiently reduce the surface of the iron-cobalt catalyst particles, thereby imparting catalytic activity for carbon nanotube growth.

<Carbon nanotube growth>
After the above reduction step is completed, the reaction temperature is continuously heated to 650 ° C. set at the reaction temperature at a heating rate of 1.3 ° C./sec. When the temperature reaches 650 ° C., the valve 5 and the valve 7 are immediately opened to remove ethanol. Ethanol vapor was introduced into the reaction furnace from the filled raw material container 21 to start growing carbon nanotubes.
During the growth of carbon nanotubes, the temperature of the quartz glass substrate is maintained at 650 ° C., the internal pressure of the furnace core tube 14 is maintained at 1.7 kPa, and is maintained for 30 minutes. Then, the supply of hydrogen gas and ethanol vapor is stopped, and the valve 4 is opened. The quartz glass substrate was cooled to room temperature while flowing argon gas through the furnace core tube 14.

Through the above steps, an optical element in which a CNT layer composed of a carbon nanotube aggregate was formed on a quartz glass substrate was obtained. The formed CNT layer was composed of a large number of carbon nanotubes standing on a quartz glass substrate, and the thickness thereof was about 100 μm.

<Evaluation of optical element>
About the produced optical element, the transmittance | permeability and the reflectance were measured.
FIG. 8A is a graph showing the reflectance when the CNT layer of the optical element is irradiated with light, and FIG. 8B is a graph showing the transmittance.
As shown in FIG. 8, in the optical element of this example provided with a CNT layer having a thickness of about 100 μm, the reflectance is less than 0.2% and the transmittance is 0.015% over the entire wavelength range of 190 nm to 890 nm. All were extremely low values. The OD value when used as an ND filter for ArF excimer laser light (wavelength 193 nm) was about 5.7. Furthermore, the reflectance of ArF excimer laser light was 0.002%. This reflectance is a remarkably low value with respect to the reflectance (several tens of percent) of the ND filter using a conventionally used chromium film and the reflectance of the quartz glass substrate (7 percent).
The OD value was measured using a spectrophotometer “Cary 5” manufactured by Varian. The reflectance was measured using a spectrophotometer “U-4000” manufactured by Hitachi, Ltd.

In addition, the above-described optical element was also evaluated for the angle characteristics of reflectance.
FIG. 9A is a graph showing changes in reflectance when the angle of light incident on the CNT layer of the optical element is changed. FIG. 9B is a schematic diagram illustrating a method of measuring the angle characteristics.
As shown in FIG. 9B, in the measurement of the angle characteristics, inspection light having a wavelength of 193.4 nm was incident on the CNT layer of the optical element from the light source 501 at a predetermined angle θ and reflected by the CNT layer. The light is detected by the detector 502. The reflectance R corresponding to the incident angle θ can be calculated from the ratio between the intensity of the light detected by the detector 502 and the intensity of the light emitted from the light source 501. In actual measurement, for example, J. et al. A. Woollam's ellipsometer “VUV-VASE (registered trademark)” can be used, and FIG. 9 (a) uses the above-mentioned ellipsometer “VUV-VASE” with an incident angle θ of 10 ° to 80 °. It is a graph which shows the result of having measured the reflectance by changing by 2 degree increments in the range.

As shown in FIG. 9A, in the optical element according to this example, a low reflectance of less than 0.35% is obtained when the incident angle θ is 80 ° or less, and the incident angle θ is 78 °. In the following range, a reflectance of less than 0.1% is obtained. Furthermore, in the range where the incident angle θ is 74 ° or less, the reflectivity is extremely low of almost 0% (below the measurement limit).
In the graph of FIG. 9A, the incident angle θ is set to 10 ° or more from the specification of the measuring apparatus, but the reflectance at the incident angle of 0 ° is almost 0% as shown in FIG. 8A. When the wavelength is 193 nm and the incident angle θ is small, the orientation direction of the carbon nanotubes and the incident direction of light are close to each other, and multiple reflection between the carbon nanotubes is likely to occur. Even in the range of from 10 ° to 10 °, the reflectance is almost 0% (below the measurement limit).

Next, durability was evaluated by continuously irradiating the produced optical element with laser light.
The produced optical element was continuously irradiated with ArF excimer laser light (frequency: 1400 Hz) having a wavelength of 193 nm under the conditions of an irradiation fluence of 1 mJ / cm ² / pulse and an O ₂ concentration of 20 ppm. The OD value and reflectance of the optical element were measured for each predetermined dose during a period until the dose reached 1.0 mJ / cm ² . After the dose reaches 1.0 mJ / cm ² , the irradiation fluence is increased to ³ mJ / cm ² / pulse and laser light is irradiated. After a predetermined period of time, the OD value and reflectance of the optical element are measured. It was.

FIG. 10A is a graph showing a change in OD value with respect to the dose amount, and FIG. 10B is a graph showing a change in reflectance with respect to the dose amount.
As shown in FIG. 10 (a) and FIG. 10 (b), the OD value and the reflectance hardly change during the period until the dose reaches 1.0 mJ / cm ² , and the CNT layer of the optical element is sufficient. It was confirmed that it had laser light resistance. Further, it was confirmed that the OD value and the reflectivity hardly changed even after the irradiation fluence was tripled and the laser beam was irradiated.

Next, the relationship between the length of the carbon nanotube constituting the CNT layer and the OD value was verified.
FIG. 11 is a graph showing the measurement results of the OD values of a plurality of optical elements produced by varying the lengths of carbon nanotubes (CNT lengths).
A plurality of optical elements having different CNT lengths in this example were produced by changing the holding time in the carbon nanotube growth step to form a CNT layer. For example, under the conditions described above, the carbon nanotube growth step was held at 650 ° C. for 30 minutes to form a CNT layer made of carbon nanotubes having a length of about 100 μm. Further, in this example, a plurality of optical elements each including a CNT layer formed by growing carbon nanotubes were produced by changing the length of the CNTs depending on the length of the holding time. And the OD value was measured about the obtained optical element using the spectrophotometer "Cary5" of a Varian company.

As shown in FIG. 11, the OD value of the optical element changes linearly with respect to the length (CNT length) of the carbon nanotubes constituting the CNT layer. From this, it was confirmed that in the optical element according to the present invention, the OD value can be adjusted by changing the length of the carbon nanotubes constituting the CNT layer. As described above, according to the optical element of the present invention in which the OD value can be freely adjusted, the set of ND filters F0 to F2 provided in the energy adjuster 233 of the exposure apparatus EX shown in FIG. 6 can be easily configured. .

100, 100A optical element, 101 substrate, 101a surface, 102 CNT layer, 103 metal film, 104 adhesive portion, 230 illumination optical system (illumination device), 242 measurement device (measurement device), 260 photodetection device, EX exposure device, PL projection optical system

Claims (16)

1. An optical element including a carbon nanotube aggregate in a region irradiated with light.
2. The optical element according to claim 1, further comprising a substrate having a light irradiation side surface on which the carbon nanotube aggregates are formed.
3. The optical element according to claim 2, further comprising a light amount adjusting film containing the carbon nanotube aggregate.
4. The optical element according to claim 2, further comprising a light absorption film containing the carbon nanotube aggregate.
5. The optical element according to claim 4, further comprising a light amount adjustment film formed between the substrate and the light absorption film.
6. The optical element according to claim 5, wherein the light amount adjustment film is a metal film.
7. The optical element according to any one of claims 2 to 6, further comprising an adhesive portion for adhering the substrate and the carbon nanotube aggregate.
8. The optical element according to claim 7, wherein the adhesion portion is unevenly distributed on the substrate side of the carbon nanotube aggregate.
9. The optical element according to any one of claims 1 to 8, wherein an orientation direction of the carbon nanotubes in the carbon nanotube aggregate substantially coincides with a direction in which the light is incident.
10. An illumination device that illuminates an object with light emitted from a light source,
    An optical element to which light from the light source is supplied;
    The illuminating device whose said optical element is an optical element of any one of Claim 1 to 9.
11. An illumination device that illuminates an object with light emitted from a light source,
    The illuminating device by which the optical element of any one of Claim 1 to 9 is arrange | positioned in the optical path vicinity of the light from the said light source.
12. An illumination device that illuminates an object with light emitted from a light source,
    An illumination device further comprising: a light detection device including the optical element according to any one of claims 1 to 9 and a measuring device that measures light via the optical element.
13. An exposure apparatus that illuminates a mask with exposure light and exposes a substrate with the exposure light from the mask,
    An exposure apparatus comprising the illumination device according to claim 10 to illuminate the mask.
14. An illumination optical system that illuminates a mask with exposure light; and a projection optical system that projects an image of a pattern of the mask illuminated with the exposure light onto the substrate,
    An exposure apparatus having the optical element according to any one of claims 1 to 9 at a position on or facing the optical path of the exposure light in at least one of the illumination optical system and the projection optical system.
15. The exposure apparatus according to claim 13 or 14, wherein at least the aggregate of carbon nanotubes of the optical element is disposed in an atmosphere mainly composed of an inert gas.
16. A device manufacturing method, comprising: exposing a substrate coated with a photosensitive agent using the exposure apparatus according to any one of claims 13 to 15; and developing the exposed substrate.

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