JP2003037040A - Optical apparatus and aligner containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical apparatus which releases unwanted gas from a housing to accommodate an optical element and obtains stable optical performance after aging, and to obtain an aligner which has the optical apparatus. SOLUTION: In the optical apparatus which holds optical members using holding members within the housing and uses optical flux via the optical elements, a space (a) including the holding members and a space (b) not including the holding members are separated by a partitioning plate. If the pressure in the space (a) is defined as P2, while the pressure in the space (b) is defined as P1, the use of a pressure control means results in the condition P2>P1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device using optical elements such as a lens, a mirror and an optical filter, and controls pressure in a space holding the optical element and a space forming an optical path in the optical device. However, it is suitable for an exposure apparatus, such as a stepper for manufacturing a semiconductor element, which maintains an optical element in a favorable environment.

[0002]

2. Description of the Related Art Optical elements such as lenses, mirrors and optical filters are, for example, cameras, telescopes, microscopes, spectroscopes,
It is used in various optical devices such as exposure devices.

In an optical element in an optical device such as a camera, a telescope or a microscope, the higher the function of the optical element, the more the optical characteristic maintaining performance of the optical element largely depends on the operating environment.

Particularly, in the exposure apparatus used in the process of manufacturing the semiconductor integrated circuit and the photomask used for manufacturing the semiconductor integrated circuit, a slight change in the characteristics of the optical element greatly affects the performance of the exposure apparatus. Further, in an optical measuring device such as a spectroscope, if the measured value changes with time due to the atmosphere in the device, it becomes a situation in which the material evaluation analysis cannot be performed accurately.

An exposure apparatus called a stepper is known as a typical exposure apparatus. The environment in which the stepper is used is a place where the atmosphere is generally controlled called a clean room. However, various solutions are used in the manufacturing site of semiconductor devices, and various devices are used to drive them, and chemical substances scattered in the environmental atmosphere are not absent. The stepper uses a shorter wavelength and requires very high optical characteristics. That is, even a slight change in the optical characteristics of the optical element is no longer acceptable. in addition,
The fact that the wavelength of light becomes shorter means that the range of chemical substances that react with the reaction process is becoming wider,
Increasingly good environmental control is needed.

On the other hand, it is proposed in Japanese Patent Laid-Open No. 02-210813 and Japanese Patent Laid-Open No. 06-216000 to purge the space atmosphere on the optical path with a purified inert gas or a filtered gas. .

[0007]

Generally, when holding an optical element such as a lens or a mirror with a lens holding frame, a holding material such as an adhesive or a cushioning material is used. From this holding material,
Gas is released by the constituents. In particular, when light in the ultraviolet region is incident on the holding material, gases of various components may be released therefrom. The gas component at that time adheres to the lens surface or the mirror surface. Further, if the product chemically adheres to the gas component in the atmosphere due to the exposure light and the product adheres to the optical element, the optical performance is significantly deteriorated.

According to the present invention, it is possible to prevent a substance that deteriorates the optical performance from adhering to the optical element, maintain the optical characteristics of the optical element at the initial values, and always obtain good optical characteristics. It is an object of the present invention to provide an optical device and an exposure apparatus having the optical device.

[0009]

According to another aspect of the present invention, there is provided an optical device, wherein an optical element is held in a housing by using a holding material, and the luminous flux transmitted through the optical element is used. The space a containing the space a and the space b not containing the holding material are separated by a partition plate, and when the pressure of the space a is P2 and the pressure of the space b is P1, the pressure control means makes P2 <P1. It is characterized by that.

According to a second aspect of the invention, in the first aspect of the invention, the pressure control means has a gas supply line for supplying gas into the housing and a gas discharge line for discharging gas from the space a. Is characterized by.

According to another aspect of the present invention, there is provided an optical device in which a holding material is used to hold an optical element in a housing, and a light flux transmitted through the optical element is used. It is characterized in that it has a gas discharge means for discharging to.

According to a fourth aspect of the invention, in the third aspect of the invention, the gas discharging means separates the space a containing the holding material from the space b not containing the holding material, and the gas in the space a to the outside of the housing. It is characterized by having a gas discharge line for discharging.

An exposure apparatus according to a fifth aspect of the present invention includes the first to fourth aspects.
It is characterized by having the optical device according to any one of 1.

[0014]

1 is a schematic view of the essential portions of Embodiment 1 of the optical device of the present invention. The optical device of this embodiment can be used in an exposure apparatus for manufacturing semiconductor elements.

In the first embodiment, the air pressure P2 in the space a containing the holding material 4 is controlled and the air pressure P1 in the other space b is controlled.

The shaded area in FIG. 1 indicates the optical path space 1.
(The optical path space here literally refers to a space through which light of the used wavelength passes.) FIG. 1 shows a cross-sectional view of a general lens 2 and a lens holding member 3. To hold the lens (circular lens) 2 and the lens holding member 3 together, a holding material 4 called a general adhesive or a cushioning material is used. The holding material 4 such as an adhesive or a buffer releases some gas from the holding material 4 due to its constituent components. In the optical device that controls the atmosphere on the optical path, these released gases have a great influence on maintaining constant optical characteristics over time. Therefore, the gas released from the holding material 4 and the like is mixed into the space atmosphere 1 on the optical path, and the gas is discharged from the inside of the holding member 3 in order to prevent the gas component from adhering to the optical element. In FIG. 1, a circular lens 2 is fixed to a cylindrical holding member 3 (hereinafter also referred to as a lens barrel) with an adhesive / buffer agent 4. This fixed portion is partitioned by a partition plate 13 formed of a member such as a metal that can be separated in a ring shape. The partition plate 13 separates the space a in which the holding material 4 in FIG. 1 is arranged from the optical path space 1 (the space b not including the holding material 4) including the hatched portion in FIG. Partition plate 13
Need not come into contact with the surface of the lens 2 as shown in FIG. Optical element (lens) for controlling the atmosphere on the optical path
A gas supply line 14 penetrating at least the inside and outside of the lens barrel is arranged in a space formed on the one surface side. Figure 1
In the above, one gas supply line 14 is arranged in each of the upper and lower spaces of the optical element (lens) 2. Further, a gas discharge line for discharging the gas supplied from the gas supply line 14 and the gas discharged from the holding material 4 in the fixing region of the optical element 2 in FIG. 1 in the space a isolated by the partition plate 13. 15 are arranged. In the middle of the gas supply line 14 and the gas discharge line 15 in FIG. 1, a gas pressure regulator 11 flowing through the line is provided.

Instead of the gas pressure regulator 11, a flow meter,
A flow controller may be placed. Discharge line 1
The pump 12 may be arranged in the middle of 5. Optical element 2
It is more preferable to arrange the pump 12 as the sealed structure of the lens barrel containing the is higher. Each of these elements 11, 12, 14
Constitutes the position element of the control means.

In the above structure, the pressure P1 in the space on the optical path and the discharge line 1 by the pressure regulator of the supply line 14
The pressure regulator of No. 5 sets the pressure P2 in the space outside the optical path so that P2 <P1. By setting the structure and setting the pressure in each space as described above, the gas released from the holding material 4 in the fixing area of the optical element 2 in FIG. 1 does not diffuse from the partition plate into the optical path space and is discharged from the discharge line 15 more quickly. Can be removed to the outside of the lens barrel 3, and the supply line 1
The gas for controlling the optical path atmosphere from No. 4 is sufficiently cleaned so that the change with time from the initial characteristics of the optical element 2 is reduced.

Here, the exhaust line 15 and the partition plate 13 constitute one element of the gas exhaust means.

FIG. 1 shows an optical system in which a light beam passes through an optical element.

In FIG. 1, a stainless steel container 3 is manufactured so that the optical element 2 and the holding material 4 can be hermetically sealed, and synthetic quartz is provided on the two surfaces facing the stainless steel side wall so that light reaches the optical element 2. Windows 16 and 17 are provided. Similarly, stainless steel pipe materials are partially welded to all of the gas lines 14 and 15 and are partially connected to each other by nuts via stainless steel ferrules. In addition, a control unit including a pressure regulator 11, a pressure sensor, a flow meter, etc. is arranged in each gas line.

The optical element 2 has antireflection films on both sides of the optical element for the wavelength range used.

As a method for confirming the effect, when the partition plate 13 is removed, when the partition plate 13 is arranged, the partition plate is arranged and the pressure control is performed, when the space b is higher than the other space a, the partition plate is arranged and the pressure is adjusted. The control was divided into the case where the space b was lower than the other space a. Gas chromatogram-mass spectroscopy method (GC-MS method) by collecting characteristic changes of optical elements due to continuous irradiation and the atmosphere on the optical path.
The qualitative and quantitative determination of the components in the optical path atmosphere was carried out. The linear introducer 18 shown in FIG. 1 is a hollow tube, and a mechanism is provided at one end to stop gas inflow with a valve during irradiation. When collecting the atmosphere, extend the pipe to the optical path with a linear introducer, and use an adsorption tube (Tenax) at a pressure and flow rate sufficiently lower than the supply gas pressure.
Organic matter in the atmospheric gas on the optical path was collected and collected in a TA 100 mg-filled glass tube). Similarly, the ionic components were similarly collected by the impinger method and evaluated by ion chromatography.

A deuterium lamp, a xenon lamp, and an excimer laser are used as the light source used, and the operation is carried out in each case. The holding material 4 for fixing the optical element is an epoxy adhesive, a silicone adhesive, an inorganic adhesive. Agents and the like were used. No matter which wavelength of light is used and which fixing material is used, comparing the changes in the optical characteristics, the partition plate 13 is removed for the configuration with the largest change, and the pressure control is performed in the space b.
Is lower than the other space a, then the partition plate 13
When the partition plate 13 is placed next, and when the partition plate 13 is placed and the pressure control is higher in the space b than in the other space a, the change in the optical characteristics of the optical element is observed in several tens of days. Was not seen.

It was confirmed by the GC-MS method and the impinger method that the total amount of components other than the supply gas in the atmosphere on the optical path also conforms to the above-mentioned permutation of optical characteristics. By investigating the detection components, the adhesive components such as phosphate ion, silicate ion, etc., which are considered to be derived from the curing agent, were detected in the inorganic adhesive, and they were not detected in the initial stage from the surface of the optical element with the changed characteristics. Element P was confirmed. Similarly, in the epoxy type, carbonyl compounds, amine type compounds,
Phenols and the like were detected, and mixed compounds which were considered to be derived from them were detected from the surface of the optical element whose characteristics had changed. Siloxane was detected in the optical environment of the silicone system.

Further, the components detected by the GC-MS method and the Impinger method in the exhaust line 15 from the fixed portion of the optical element 2 separated by the partition plate 13 are removed by the partition plate 13 at the time of the material used. In this case, the same components as those detected from the optical path atmosphere were observed. Thus, by arranging the partition plate and setting the pressure P1 of the optical path atmosphere b to be higher than the pressure P2 of other regions, the optical path atmosphere is controlled by a clean supply gas, and the other atmosphere is realized. It was confirmed that the gas released from the parts and members was selectively discharged before entering the optical path atmosphere, and it was possible to avoid the influence on the characteristic change of the optical element 2.

In addition to this embodiment, spaces for driving parts, surface-treated parts, etc. in the optical device are separated from the optical path by a partition plate, and the pressure of these spaces is controlled by the atmosphere on the optical path in the same optical device. By setting the pressure lower than the pressure, it is possible to prevent the emission components from these constituent parts from entering the optical path and suppress the characteristic change of the optical element.

With such a structure and configuration, the control of the space atmosphere on the optical path is well realized without being affected by the gas components emitted from the peripheral members.

By separating the holding mechanism portion, the holding material, the drive region, and the like used in the above structure and the optical device from the optical path and controlling the pressure of each space, the space atmosphere on the optical path is controlled. Are controllable. Further, an optical device that can maintain good initial performance without being restricted by the materials and mechanisms used in the device, compared to the conventional purging in the optical device, is realized.

FIG. 2 is a schematic view of the essential portions of Embodiment 2 of the present invention. In this embodiment, a reflection type optical element 21 is used as an optical element as compared with the first embodiment of FIG. 1, the optical element 21 is fixed to a fixing pedestal 22 with an adhesive 23 as a holding material, and the holding material 23 is fixed. The only difference is that the partition plate 13 separates the space a containing it and the space b not containing the holding material 23 by the partition plate 13, and the other configurations are the same.

The same elements as those shown in FIG. 1 are designated by the same reference numerals.

Also in this embodiment, in the optical device having the optical element 21, the pressure P1 in the space b on the optical path due to the pressure of the pressure regulator in the line 14 and the pressure P2 in the space a outside the optical path by the pressure regulator in the line 15 are set. By maintaining the relationship of P2 <P1 between them, it is possible to suppress the change with time from the initial characteristics of the optical element in the optical device. In addition, a simple partition structure can keep the optical path atmosphere clean. We have achieved an optical device that is less susceptible to characteristic deterioration over time without increasing the cost of the device due to special materials and surface treatment.

FIG. 3 is a schematic view of a main part of a projection exposure apparatus using the optical device of the present invention.

The present embodiment shows a case where the present invention is applied to a normal step-and-repeat type stepper (projection exposure apparatus).

In the figure, reference numeral 34 designates an exposure illumination system.
A reticle (mask) 31 as an object is illuminated.
The exposure illumination system 34 is an ArF excimer laser (wavelength 193
nm) or KrF excimer laser (wavelength 248n
m) or a g-line (436 nm) or i-line (365 nm) emitting lamp. Three
Reference numeral 8 is a projection device.

In this embodiment, at least one of the exposure illumination system 34 and the projection device 38 is provided with the optical device shown in FIG.

Reference numeral 31 is a reticle (mask) as a first object. Reference numeral 32 denotes a projection optical system such as a refraction type or catadioptric system, which projects the circuit pattern of the reticle 31 illuminated by the exposure illumination system 34 onto a wafer 33 (exposed substrate) as a second object.

Reference numeral 35 denotes a wafer holder, which holds the wafer 33. 36 is a wafer stage,
A wafer holder 35 is mounted, and well-known xyz drive, θ drive, tilt drive, etc. are performed.

Reference numeral 37 is an interference mirror for monitoring the position of the wafer stage 36 with an interferometer (not shown). The wafer 33 is positioned at a predetermined position by a wafer stage drive control system (not shown) using signals obtained from the interferometer mirror 37 and the interferometer, and projection exposure is performed in that state.

[0040]

According to the present invention, it is possible to prevent a substance that deteriorates the optical performance from adhering to the optical element, maintain the optical characteristics of the optical element at the initial values, and always obtain good optical characteristics. It is possible to achieve an optical device configured as described above and an exposure apparatus including the optical device.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a schematic view of a main part of a second embodiment of the present invention.

FIG. 3 is a schematic view of a main part of a projection exposure apparatus of the present invention.

[Explanation of symbols]

1 Optical path space 2,21 Optical element 3 holding member 4 holding material 11 Gas pressure regulator 12 pumps 13 partition boards 14 Supply line 15 discharge line 22 pedestal 23 Adhesive

Claims (5)

[Claims] 1. An optical device that holds an optical element by using a holding material in a housing and utilizes a light flux passing through the optical element, wherein a space a containing the holding material and a space b not containing the holding material are provided. Separated by a partition plate, the pressure of the space a is P2, and the space b is
An optical device, wherein the pressure control means sets P2 <P1 when the pressure of P1 is P1. 2. The optical device according to claim 1, wherein the pressure control means has a gas supply line for supplying gas into the housing and a gas discharge line for discharging gas from the space a. . 3. An optical device for holding an optical element by using a holding material in a housing and utilizing a light flux passing through the optical element, a gas discharging means for discharging a gas generated from the holding material to the outside of the housing. An optical device characterized by having. 4. The gas discharge means has a partition plate for separating a space a containing the holding material and a space b not containing the holding material, and a gas discharge line for discharging the gas in the space a to the outside of the housing. The optical device according to claim 3, wherein: 5. An exposure apparatus comprising the optical device according to any one of claims 1 to 4.