Photocopying – Projection printing and copying cameras – With temperature or foreign particle control
Reexamination Certificate
2001-09-10
2004-07-13
Fuller, Rodney (Department: 2851)
Photocopying
Projection printing and copying cameras
With temperature or foreign particle control
C355S053000
Reexamination Certificate
active
06762820
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention relates to an exposure apparatus and a device manufacturing method. More particularly, the present invention relates to an exposure apparatus used in a lithography process in manufacturing semiconductor devices, liquid crystal devices and the like, and a device manufacturing method with which exposure is performed by using the exposure apparatus.
2. Description of The Related Art
Since before, in a lithography process to manufacture semiconductor devices, liquid crystal display devices and the like, a reduction projection exposure apparatus of a step-and-repeat method (a so-called stepper) and a scanning projection exposure apparatus of a step-and-scan method (a so-called scanning stepper) have been mainly used.
In recent years, the exposure apparatuses have used shorter wavelengths for exposure under the demand for improvement of resolution responding to finer circuit patterns in accordance with higher integration of semiconductor devices and the like. Currently, a KrF excimer laser with an oscillation wavelength of 248 nm and an ArF excimer laser with a shorter oscillation wavelength of 193 nm are used as a light source. In the exposure apparatus using such a light source with a short wavelength, from a viewpoint that the sensitivity of resist needs to be increased to compensate for the shortage of brightness of each light source, a high sensitive, chemically amplified resist has been used as the resist that coats a substrate. The sensitive emulsion of the chemically amplified resist contains acid generating agent; catalytic reaction is induced in a subsequent thermal processing (PEB: post-exposure-bake) by the acid generated in exposure, and insolubleness (negative type) or solubleness (positive type) of the resist to a developer is promoted.
It has been found out recently that a trace of gas in the atmosphere causes adverse effect to the exposure apparatus. For example, when a substrate is coated with a positive type chemically amplified resist, a phenomenon occurs that a trace of base gas of a ppb level in the atmosphere neutralizes an acid catalysis generated on the surface of the positive type chemically amplified resist to form a surface hard-soluble layer, and that a resist's section, which is to be rectangular, is shaped like a visor called a T-shape that resembles a letter T after the exposure and development are performed. Overcoat is needed since the chemically amplified resist as a high sensitive resist cannot be used alone, and thus the throughput reduces.
Moreover, with shorter wavelengths and higher illumination of an exposure beam, for example, ammonia gas, sulfur oxide, organosilicon and the like in the atmosphere chemically react to strong energy of short wavelength ultraviolet light and precipitate on the surfaces of optical elements in the exposure apparatus as tarnish substances. It has been found out that a certain amount of the precipitation causes the scattering and the absorption of light beams and thus phenomena such as the decreases of degree and uniformity of illumination on the irradiated surface. Accordingly, it is becoming a matter of importance to control chemical pollutants in the atmosphere to a low concentration.
For this reason, it is required that the environment inside a current exposure apparatus is strictly controlled.
On the other hand, since the exposure apparatus is an extremely precise apparatus, the temperature state inside the apparatus needs to be controlled to a constant level in order to make each section thereof exert its desired performance. For such temperature control, a conventional exposure apparatus is designed to keep the space inside an environmental chamber in a uniform temperature distribution by sending a gas, whose temperature is controlled by a temperature control unit, into the environmental chamber where the exposure apparatus main body is housed. In addition, to keep the concentration of the foregoing chemical pollutants such as ammonia to a low level, the chemical pollutants need to be removed before the gas whose temperature is controlled is sent into the environmental chamber. For this purpose, a filter unit that removes chemical pollutants in the gas by chemical adsorption and physical adsorption (hereinafter, also referred to as a “chemical filter” for convenience) is generally used.
There is no doubt that realization of higher integration of semiconductor devices will be required in future. Accordingly, an exposure apparatus is required to realize even more accurate exposure. Thus, further improvement of performance of each element in the exposure apparatus is demanded. One such demand is further improvement of the temperature control performance inside the environmental chamber.
However, it has been found recently that when gas for air conditioning, e.g., air of which the temperature fluctuation amount relative to a target temperature is strictly controlled to a value or less by an air conditioner or the like is sent into the environmental chamber to highly accurately control the temperature inside the environmental chamber, the temperature fluctuation amount, relative to the target temperature, of the air sent into the chamber increases in the environmental chamber. Therefore, the temperature fluctuation is likely to block the realization of higher exposure accuracy required in the future.
The inventors presumed that constituents for improving the exposure accuracy cause the above increase of the temperature fluctuation amount because it has appeared after the exposure accuracy has become greatly high, and repeated various kinds of experiments and the like under the presumption. As a result, the inventors found out that the temperature fluctuation amount of the air increases after the air passes through the foregoing chemical filter unit rather than before.
SUMMARY OF THE INVENTION
The present invention was made based on the foregoing novel findings obtained by the inventors. A first object of the present invention is to provide an exposure apparatus capable of simultaneously limiting the illumination reduction caused by tarnish of optical members and an increase of the temperature fluctuation amount.
A second object of the present invention is to provide a device manufacturing method capable of manufacturing highly integrated micro-devices with good productivity.
According to the first aspect of this invention, there is provided an exposure apparatus, comprising: an exposure apparatus main body that exposes a substrate to an energy beam so as to form a predetermined pattern on said substrate; a main body chamber that encloses at least a portion of said exposure apparatus main body; an environmental control unit connected to said main chamber to supply a predetermined gas into said main body chamber to control an environment inside said main body chamber; and at least one first filter unit that is arranged in a portion of a ventilation path of said gas supplied into said main body chamber by said environmental control unit, removes chemical pollutants from said gas, and controls temperature fluctuation of said gas after passing through the first filter unit to within a predetermined range.
The ventilation path of the gas supplied into the main body chamber by the environmental control unit is not limited to the ventilation path between the environmental control unit and the main body chamber, but specifically includes an air-supply path in the environmental control unit and the main body chamber, in its concept.
With this ventilation path, the first filter unit that removes chemical pollutants from the gas and controls the temperature fluctuation of the gas after passing the filter unit to within the predetermined range is arranged in a portion of the ventilation path of the gas supplied into the main body chamber by the environmental control unit. Accordingly, the space including the ventilation path in the downstream of the first filter unit has an atmosphere from which chemical pollutants is removed and the temperature
Hashimoto Michinori
Karibe Fumio
Udagawa Kenji
Yoshida Tomoyuki
Fuller Rodney
Nikon Corporation
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