Photocopying – Projection printing and copying cameras – Illumination systems or details
Reexamination Certificate
1998-12-11
2001-08-21
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Illumination systems or details
C355S053000, C355S073000
Reexamination Certificate
active
06278516
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a projection exposure apparatus used, in a process of producing a semiconductor device such as an IC or LSI, to project a laser beam onto a substrate so as to form thereon a reduced image of a circuit pattern of a reticle (also called a mask).
In recent years, great advances have been made in the technology of producing semiconductor devices. With great advances in general semiconductor production technology, great advances have also been made in the microlithography technology. With the most advanced photolithography technology, it is possible to obtain high resolution in the sub-micron range. One possible method to further improve the resolution is to increase the NA (numerical aperture) of an optical system using exposure light with a fixed wavelength. Another method is to reduce the wavelength of the exposure light.
Various techniques based on the latter method have been proposed to improve the resolution using ultraviolet light with a small wavelength such as an excimer laser beam. The excimer laser apparatus, unlike conventional light sources such as a super-high pressure mercury lamp for emitting i-line light, is very large in size and weight, and thus it is installed separately from the main part of an exposure apparatus. Furthermore, in order to minimize the apparatus installation space in a clean room and also for the reason of safety, the excimer laser generator is installed, in most cases, in a room separated from a room in which the main part of the exposure apparatus is installed. For example, the excimer laser apparatus is installed in a room on a floor below the clean room or in a room which is on the same floor as the clean room but which is isolated from any other rooms.
The laser beam generated by the laser apparatus is transmitted to the exposure apparatus directly or through a plurality of light deflection elements such as mirrors, or through another type of optical path properly selected depending on the installation conditions. In any case, it is required that the optical path between the laser apparatus and the main part of the exposure apparatus should be tightly shielded. As is well known, a highly reliable safety system is required to ensure that no strong ultraviolet radiation such as an excimer laser beam leaks outward from the optical path. It is desirable that the inside of the optical path be purged with an inert gas such as nitrogen so that the optical elements in the optical path are prevented from being degraded. That is, it is required that the projection exposure apparatus using a laser beam should meet both requirements described above.
In view of the above, it is a general object of the present invention to solve the above problems. More specifically, it is an object of the invention to provide a technique which makes it possible to perform maintenance of the laser beam path of a projection exposure apparatus while ensuring complete safety, without causing degradation of optical elements, and at low cost.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, to achieve the above objects, there is provided a projection exposure apparatus capable of detecting projection exposure conditions in the middle of a laser beam irradiation path, the projection exposure apparatus comprising: a laser source for generating a laser beam; an illumination optical unit for illuminating a reticle with the laser beam; a projection optical unit for projecting a pattern of the reticle onto a wafer; a light shielding member in which the path of the laser beam emitted by the laser source is enclosed and in which an inert gas is supplied; a removable enclosure for enclosing the light shielding member; an insertion slot formed in the light shielding member so that a detector for detecting a physical or chemical characteristic in the vicinity of the laser beam path may be inserted into the insertion slot; and a light shielding lid provided on the light shielding member, the light shielding lid being capable of being opened and closed when the detector is inserted or removed, wherein when the detector is inserted, the light shielding lid is pushed into its open position whereas when the detector is removed, the light shielding lid moves into a closed position and rests in the closed position in which the insertion slot is closed with the light shielding lid.
According to a second aspect of the present invention, there is provided a projection exposure apparatus capable of detecting projection exposure conditions in the middle of a laser beam irradiation path, the projection exposure apparatus comprising: a laser source for generating a laser beam; an illumination optical unit for illuminating a reticle with the laser beam; a projection optical unit for projecting a pattern of the reticle onto a wafer; a light shielding member in which the path of the laser beam emitted by the laser source is enclosed and in which an inert gas is supplied; a removable enclosure for enclosing the light shielding member; an insertion slot formed in the light shielding member so that a detector for detecting a physical or chemical characteristic in the vicinity of the laser beam path may be inserted into the insertion slot; and a tight sealing lid provided on the light shielding member, the tight sealing lid being capable of being opened and closed when the detector is inserted or removed wherein when the detector is inserted, the tight sealing lid comes into an open position in which the tight sealing lid prevents the enclosure from being placed in the normal position.
According to a third aspect of the present invention, there is provided a projection exposure apparatus capable of detecting projection exposure conditions in the middle of a laser beam irradiation path, the projection exposure apparatus comprising: a laser source for generating a laser beam; an illumination optical unit for illuminating a reticle with the laser beam; a projection optical unit for projecting a pattern of the reticle onto a wafer; a light shielding member in which the path of the laser beam emitted by the laser source is enclosed and in which an inert gas is supplied; a removable enclosure for enclosing the light shielding member; an insertion slot formed in the light shielding member so that a detector for detecting a physical or chemical characteristic in the vicinity of the laser beam path may be inserted into the insertion slot; and a lid disposed on the insertion slot and capable of being opened and closed when the detector is attached or removed.
According to a fourth aspect of the invention, there is provided a method of producing a semiconductor device, including a projection exposure step using a projection exposure apparatus according to the first aspect described above.
According to a fifth aspect of the invention, there is provided a method of producing a semiconductor device, including a projection exposure step using a projection exposure apparatus according to the second aspect described above.
According to a sixth aspect of the invention, there is provided a method of producing a semiconductor device, including a projection exposure step using a projection exposure apparatus according to the third aspect described above.
In the projection exposure apparatus according to the above-described second aspect of the invention, the projection exposure apparatus may further include a light shielding lid provided on the light shielding member, the light shielding lid being capable of being opened and closed when the detector is inserted or removed, wherein when the detector is inserted, the light shielding lid is pushed into its open position whereas when the detector is removed, the light shielding lid moves into a closed position and rests in the closed position in which the insertion slot is closed with the light shielding lid.
In the projection exposure apparatus according to the above-described first aspect of the invention, the light shielding lid may include a mechanism whereby when the detector is inserte
Miwa Yoshinori
Yamana Tetsumi
Adams Russell
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Fuller Rodney
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