Photocopying – Projection printing and copying cameras – With temperature or foreign particle control
Reexamination Certificate
2001-11-27
2004-08-31
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
With temperature or foreign particle control
C355S053000
Reexamination Certificate
active
06784972
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exposure apparatus, a device manufacturing method and an environmental control of an exposure apparatus. More particularly, the present invention relates to an exposure apparatus used in a lithography process in manufacturing semiconductor devices, liquid crystal display devices and the like, a device manufacturing method in which exposure is performed by using the exposure apparatus, and an environmental control method to keep environmental conditions inside an exposure chamber of the exposure apparatus substantially constant.
2. Description of The Related Art
In an apparatus performing processing for fine features such as a semiconductor exposure apparatus, an air conditioning system is provided to adjust temperatures therein because the temperatures need to be adjusted with extremely high accuracy. In this case, the air conditioning system needs to be a circulating system since very precise temperature adjustment needs to be performed within a range of, for example, ±0.1° C. relative to a target temperature. Accordingly, a blower is required for circulating air. In the exposure apparatus, a machine chamber housing an air conditioner including the blower is normally installed independently of a main body chamber housing an exposure apparatus main body because of problems of vibration and the like.
In the exposure apparatus that manufactures electronic devices such as LSI's and the like, pressure inside the main body chamber housing the exposure apparatus main body, which consists a reticle, a projection lens and the like, is usually set to be higher than that of the outside of the main body chamber. The air inside the main body chamber leaks to the outside due to a pressure difference between the inside and the outside of the main body chamber, air needs to be supplied from the outside to compensate for the lost air. Accordingly, an outside air inlet called an OA port is provided in part of a supply path of the air (a supply path) to the main body chamber, and outside air is normally, naturally fed through the OA port.
On the other hand, the air that has returned from the main body chamber enters the air conditioner in the machine chamber together with supply air from the outside. The air that has entered the air conditioner is cooled down by a cooler. At this point, excess moisture brought from the outside by the feeding of the outside air condenses on the radiation fins of the cooler and so is removed. Then, the air from which the excess moisture has been removed is heated to a given temperature by a heater, and sent into the main body chamber by the blower.
In addition, it has recently been found out that trace level gas in a clean room atmosphere has adverse effects on a semiconductor manufacturing apparatus such as a reduction projection exposure apparatus (a stepper) and the like. More specifically, in an excimer laser exposure apparatus, an X-ray exposure apparatus or an electron beam exposure apparatus, which uses an excimer laser such as a KrF excimer laser, an ArF excimer laser or the like as a light source, a high sensitive chemically amplified resist is used in order to compensate for insufficient brightness of the light source. The chemically amplified resist contains an acid-generating agent as a photosensitive agent, and acid generated by the agent upon exposure induces catalytic reaction in a subsequent thermal processing (PEB: post exposure bake) so as to make the exposed part of the resist insoluble (a negative type) or soluble (a positive type) in a developing solution. However, in the case of a positive resist, trace level basic gas of a ppb level in the atmosphere may neutralize acid catalyst generated on the surface of the positive type chemically amplified resist to form a hardly-soluble surface layer. In such a case, the phenomenon occurs that after being exposed and developed, a cross section of the resist, which should be rectangular, is made into a shape like a letter T (referred to as a T-shape) When such a hardly-soluble surface layer is formed, the benefit of using the chemically amplified resist, which is a high sensitive resist, is lost. In order to proceed to exposure, overcoat or the like is necessary, which reduces throughput.
Further, as the exposure light becomes shorter in wavelength and more intense in illuminance, the phenomenon also occurs that trace level gas in the atmosphere precipitates as tarnish substances, which adhere to the surfaces of optical members forming an illumination system. Such a phenomenon occurs due to photochemical reaction between the trace level gas in the atmosphere and the exposure light. Reactive substances are ammonia gas, sulfur oxide, organic silicon compound and the like in the air. As a result of generation of tarnish on the optical members forming the illumination system, the illuminance is greatly reduced so that the throughput is reduced.
Therefore, means for removing a trace of impurity gas in a clean room atmosphere are disclosed in, for example, Japanese Patent Laid-Open No. 6-77114 and the U.S. Pat. No. 5,430,303 corresponding thereto.
With respect to conventional exposure apparatuses, a method where an exposure apparatus main body, and a substrate transportation system transporting a photosensitive substrate such as a wafer or a mask transportation system are housed in one environmental control chamber, and another method where the exposure apparatus main body, and the substrate transportation system or the mask transportation system are housed in different environmental control chambers are known.
In both methods, either one of the following techniques has been adopted. One is that air is blown into the inside of the exposure chamber that houses the exposure apparatus main body sideways (side-flow) from the side other than a side where the substrate transportation system and the mask transportation system are installed, and the other one is that air is blown downward (down-flow) from the ceiling to the floor of the exposure chamber.
According to the invention disclosed in the foregoing Japanese Patent Laid-Open, a trace of impurity gas in a clean room atmosphere can be surely removed to a certain extent, and reduction in illuminance due to tarnish on the optical members and generation of the hardly-soluble surface layer of the chemically amplified resist can be limited.
Recently, however, as the feature sizes of semiconductor devices become finer, outgas from an adhesive agent, a sealing agent, paint and components used in exposure apparatuses, which caused no problem in the past, is coming to pose problems that cannot be ignored, and the exposure apparatus main body itself can be regarded as a source of contamination. To get rid of influences of the outgas, the insides of an exposure apparatuses are required to be chemically clean, and chemical filters to remove chemical substances are commonly installed in exposure apparatuses similarly to the invention disclosed in the foregoing Japanese Patent Laid-Open.
However, in a conventional exposure apparatus, since a filter that removes impurities is provided only at the outside air inlet or a supply path to the inside space of the main body chamber; chemically contaminated air containing outgas released from the exposure apparatus main body when performing air conditioning thereof returns to an air conditioner and then is sent into the chemical filter disposed in the supply path by a blower of the air conditioner. Accordingly, the lifetime of the chemical filter in the supply path shortens particularly, and the chemical filter must be frequently replaced with a new one. Further, design of the conventional exposure apparatus has made on the presupposition that replacement of the chemical filter is unnecessary during the life of the apparatus. That is, replacement of the chemical filter itself has never been taken into consideration. Therefore, a chemical filter other than the one at the outside air inlet is normally disposed in a position where rep
Kamiya Saburo
Katsura Koichi
Nagahashi Yoshitomo
Adams Russell
Esplin D. Ben
Nikon Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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