Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-03-29
2004-11-30
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C204S298250, C118S719000
Reexamination Certificate
active
06826442
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a stocker for stocking an object to be stocked such as a reticle or wafer in a semiconductor manufacturing process, an exposure apparatus having the stocker, a device manufacturing method, a semiconductor manufacturing factory, and an exposure apparatus maintenance method and, more particularly, to a stocker for an object to be stocked in an exposure apparatus using an F
2
excimer laser as an exposure light source.
BACKGROUND OF THE INVENTION
In recent years, the wavelength of an exposure light source used in an exposure apparatus is becoming much shorter in the manufacture of a semiconductor device. A short wavelength increases the resolution of a projection, exposure system concerning exposure, which enables exposure of a finer pattern. An F
2
excimer laser has a wavelength as short as 157 nm, and is being applied to an exposure apparatus. The wavelength of 157 nm falls within a wavelength region generally called a vacuum ultraviolet region. In this wavelength region, light is greatly absorbed by oxygen molecules and hardly passes through outer air. Thus, the F
2
excimer laser can be applied in only an environment in which the atmospheric pressure is decreased to almost vacuum and the oxygen concentration is sufficiently decreased. According to a reference “Photochemistry of Small Molecules” (Hideo Okabe, A Wiley-Interscience Publication, 1978, page 178), the absorption coefficient of oxygen with respect to light having a wavelength of 157 nm is about 190 atm
−1
cm
−1
. This means that a transmittance T per cm is only T=exp(−190×1 cm×0.01 atm)=0.150 when light having a wavelength of 157 nm passes through gas having an oxygen concentration of 1% at one atmospheric pressure.
Japanese Patent Publication 5-66733 discloses an interface apparatus for an integrated circuit. This apparatus relates to a box for storing integrated circuit wafers and an interface for the wafers in the box. The earlier publication also discloses exchange of wafers so as to inhibit entrance of foreign matter such as dust.
In an exposure apparatus using an F
2
excimer laser, absorption by oxygen at a wavelength of 157 nm is conspicuous. To obtain a satisfactory transmittance, the oxygen concentration must be reduced to 1 ppm or less, and the concentration must be strictly controlled. Members which are frequently loaded/unloaded into/from the exposure apparatus are wafers and reticles (including masks), which are usually stocked in a clean room or the like. The oxygen concentration cannot be satisfactorily reduced even by arranging a mechanism for reducing oxygen in transporting a wafer or reticle to the exposure apparatus. Such a mechanism becomes an oxygen mixing source into the exposure apparatus, and decreases the yield of the exposure apparatus.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation, and has as its object to stock a reticle or wafer in an atmosphere in which the oxygen concentration is reduced to about 5 ppm before the reticle or wafer is transferred to an exposure apparatus.
It is another object of the present invention to transport a reticle or wafer in an oxygen-concentration-reduced atmosphere to an exposure apparatus without exposing the reticle or wafer to outer air.
To achieve the above objects, according to the present invention, a stocker for stocking an object to be stocked such as a reticle, mask, or wafer has the following arrangement.
According to the first arrangement, a stocker comprises a first sealing member, atmosphere control means for controlling an internal atmosphere of the first sealing member to a first atmosphere, and transfer means for transporting an object to be stocked to an exposure apparatus or receiving the object to be stocked from the exposure apparatus without exposing the objects to be stocked to an external atmosphere of the first sealing member, wherein at least one object to be stocked is stocked in the first sealing member.
According to the second arrangement, a stocker comprises a first sealing member, first atmosphere control means for controlling an internal atmosphere of the first sealing member to a first atmosphere, a second sealing member for storing at least one object to be stocked, second atmosphere control means for controlling an internal atmosphere of the second sealing member to a second atmosphere, and transfer means for transporting the object to be stocked to an exposure apparatus or receiving the object to be stocked from the exposure apparatus while the object to be stocked is stored in the second sealing member without being exposed to an external atmosphere of the first sealing member, wherein at least one second sealing member, which stores at least on object to be stocked, is stocked in the first sealing member.
The stocker of the present invention may further comprise a load-lock chamber. In this case, the object to be stocked is transported to the outside of the first sealing member or received from the outside of the first sealing member via the load-lock chamber, At this time, the object to be stocked is preferably transported to the outside of the first sealing member or received from the outside of the first sealing member while stored in the second sealing member.
The stocker may further comprise atmosphere measurement means such as oxygen analyzers for measuring the internal atmospheres of the first sealing member and/or the second sealing member. In the first arrangement, it is desirable that the first atmosphere have an oxygen concentration of 50 ppm or less. In the second arrangement, it is desirable that the first atmosphere have an oxygen concentration of 50 ppm or less and the second atmosphere have an oxygen concentration of 5 ppm or less. In either case, the first and second atmospheres are usually an inert gas atmosphere, and preferably, a nitrogen gas atmosphere, a helium gas atmosphere, or a gas mixture atmosphere of nitrogen gas and helium gas. For this purpose, the atmosphere control means preferably has gas injection means for injecting inert gas or the like, or evacuation means for discharging gas from the stocker.
The stocker of the present invention is desirably connected to the exposure apparatus via a highly airtight transfer path, and is suitable for an exposure apparatus using an F
2
excimer laser as an exposure light source.
For example, transfer means for transporting the object to be stocked to manufacturing apparatuses for performing various processes or receiving the object to be stocked from the manufacturing apparatuses for performing various processes is desirably arranged in a semiconductor manufacturing line.
In a reticle or mask stocker, a desired one of stocked reticles or masks is supplied to the exposure apparatus by, e.g., a reticle changer.
With this arrangement, the object to be stocked can be transported to the exposure apparatus without being exposed to outer air while the oxygen concentration in the stocker is maintained at 50 ppm or less and, especially, the oxygen concentration around the substrate such as a reticle or wafer is maintained at about 5 ppm. The oxygen concentration can be quickly reduced to 1 ppm or less by loading the object to be stocked into the exposure apparatus via, e.g., the load-lock chamber. The evacuation means is adopted to repeat discharge and gas injection, which can reduce the oxygen concentration to about 5 ppm faster than the case of only gas injection. Particularly, in an exposure apparatus using an F
2
excimer laser as a light source, a high-quality semiconductor device can be manufactured while absorption of a laser beam is reduced and the yield is kept high.
An exposure apparatus of the present invention for transferring a pattern drawn on a reticle or mask to the wafer by exposure comprises a stocker having the above features in order to stock substrates such as reticles, masks, or wafers.
The exposure apparatus of the present invention further comprises a display, a network interface, an
Murakami Eiichi
Takeuchi Seiji
Kosowski Alexander
Picard Leo
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