Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition – Control element is fluid pressure sensitive
Reexamination Certificate
1999-02-25
2003-09-09
Tran, Hien (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
Control element is fluid pressure sensitive
C422S105000, C422S109000, C422S110000, C118S715000, C118S7230VE
Reexamination Certificate
active
06616898
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a processing apparatus equipped with a sealed vacuum device which contains a processing portion. In particular, it relates to a processing apparatus suitable for the manufacture of a semiconductor element, or the like. It also relates to a device manufacturing method which employs such a processing apparatus.
In the manufacture of a semiconductor element or the like, an exposing apparatus is used. As semiconductor elements have been rendered microscopic and highly integrated, X-ray has come to attract attention as one of the most promising choices of exposing light. The rate of the X-ray attenuation caused by the presence of the atmospheric air is extremely high. Therefore, when an X-ray is used as the exposure beam for a semiconductor exposing apparatus, the X-ray is guided into an exposure chamber through a beam duct which has been evacuated to an extremely high degree. In an exposure chamber, a substrate positioning stage and a mask holding apparatus are placed. A substrate positioning stage accurately positions a piece of substrate wafer or the like with the use of a chuck activated by suction. A mask holding apparatus holds a mask. In order to accurately expose the predetermined area of a piece of substrate by an exposure beam, the substrate piece must be very accurately positioned. Therefore, a laser interferometry based measuring device, or the like, is placed in an exposure chamber to measure the position of the substrate positioning stage in the chamber. In order to prevent X-ray attenuation, the atmospheric air in an exposure chamber is evacuated, creating a virtual vacuum chamber, while filling the evacuated exposure chamber with a small amount helium gas or the like to enhance the heat dissipation from the substrate in the wafer form, or a mask. Further, an exposure chamber is structured so that the pattern of the mask held by a mask holding apparatus is transferred onto the substrate by the X-ray as exposure light.
The internal pressure of an exposure chamber, or a vacuum chamber, affects the amount of X-ray transmission through the chamber. In other words, the change in the internal pressure of the vacuum chamber causes nonuniform exposure. The vacuum level falls as the atmospheric air, the gases from the bearings or the like, of the aforementioned positioning stage or the like, leak into the vacuum chamber, which in turn reduces the amount of the X-ray transmission through the internal space of the vacuum chamber. In other words, this kind of vacuum loss in an exposure chamber, or a vacuum chamber, is one of the main reasons why the performance of an exposing apparatus deteriorates in accuracy, and also why the throughput of an exposure apparatus reduces. Further, the internal temperature of a vacuum chamber locally increases due to the heat sources contained in the vacuum chamber, for example, the actuator or electrical wiring of the substrate positioning stage, the laser, or the like. Also, the internal temperature of the vacuum chamber is locally increased by the heat from the exposure light projected onto the substrate wafer and the mask. This kind of local temperature increase deforms the mask and the substrate, making it impossible to desirably transfer the mask pattern. In addition, the local temperature fluctuation creates a turbulence in the ambience gas in the measurement path of the laser beam projected by the laser interferometry based measuring device in the vacuum chamber, which results in fluctuation in the refractive index of this portion of the ambience gas. The fluctuation of the refractive index makes it impossible to accurately measure the position of the substrate positioning device with the use of a laser interferometry based measuring device. Thus, the pressure, temperature, and degree of purity of the gas in an exposure chamber, or a vacuum chamber, must be very precisely controlled as is evident from the above explanation.
Thus, the air in an exposure chamber, that is, a sealed container, is replaced with a small amount of inert gas such as pure helium, so that the internal space of the exposure chamber becomes a virtual vacuum space. Known as a method for keeping the gas in the exposure chamber pure while maintaining the internal space of the exposure chamber in the virtual vacuum state is the method disclosed in U.S. Pat. No. 5,267,292, which corresponds to EP application no. 363,168, for example. According to this patent, the internal pressure of the exposure chamber, or the sealed container, is kept constant by adjusting the flow rate at which the ambient gas in the exposure chamber is exhausted from the exposure chamber, and the flow rate at which very pure gas is allowed to flow into the exposure chamber, based on the internal pressure of the exposure chamber detected with the use of a pressure sensor. In this case, the flow rate at which the pure gas is allowed to flow into the exposure chamber is a certain number of times the flow rate at which unwanted gases flow into the exposure chamber.
Further, the following technology is disclosed in Japanese Laid-Open Patent Application No. 156625/1990. Thus, according to this patent, a sealed chamber is employed as an exposure chamber in which X-ray is used as exposure light. In operation, the atmospheric air in the sealed chamber is evacuated, and is replaced with a small amount of gas, for example, helium gas. As for the operational fluid for the static pressure bearings for the positioning stage in the evacuated sealed chamber (hereinafter, “vacuum chamber”), the ambient gas, that is, helium gas, in the vacuum chamber is used; the ambient gas is fed to the static pressure bearing after its pressure is increased with the use a compressor. The internal pressure of the vacuum chamber is controlled by adjusting the flow rate at which the helium gas, or the ambient gas, in the vacuum chamber is exhausted. More specifically, the internal pressure of the vacuum chamber is detected, and the flow rate at which the ambient gas in the vacuum chamber is exhausted by a vacuum pump is adjusted in response to the detected internal pressure of the vacuum chamber, so that the internal pressure of the vacuum chamber remains virtually constant. The helium gas suctioned out of the vacuum chamber by the vacuum pump is recirculated into the vacuum chamber to reduce helium gas consumption, while keeping constant the purity of the helium gas in the vacuum chamber so that exposure does not become uneven.
Japanese Laid-Open Patent Application No. 264404/1996 also discloses an ambient gas recirculating system. According to this patent, the ambient gas in a vacuum chamber is suctioned out by a vacuum pump, so that the internal pressure of the vacuum chamber remains constant at a predetermined level. The ambient gas suctioned out of the vacuum chamber is compressed by a compressor, and stored in a tank. Then, this ambient gas compressed and stored in the tank is recirculated into the vacuum chamber after being purified by a gas purifier, so that the rate at which ambient gas such as helium gas, which is rather expensive, is utilized, is improved, reducing thereby the cost for running the apparatus.
There is a technology for controlling the internal environment, of a semiconductor exposing apparatus, the ambient gas of which is the atmospheric air. According to this technology, the chamber in which an exposing apparatus is placed is connected to an air conditioning apparatus, which prevents the internal temperature of the chamber from being increased by the heat sources, for example, a mechanical power source such as a motor, electrical wiring, a laser, and the like, in the chamber, so that the internal temperature of the chamber remains constant at a predetermined level. This type of air conditioning apparatus is constituted of a fan, and a heat exchanger such as a heater or a cooler. It takes in the air from within a chamber or the atmospheric air, adjusts the temperature of the air by the heat exchanger, and sends the air into the chamber b
Hara Shin-ichi
Hasegawa Takayuki
Matsui Shin
Tanaka Yutaka
Terashima Shigeru
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Tran Hien
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