Patent Application
20070268467
The embodiments of the present invention will be described below with reference to the accompanying drawings.
An air intake port 2 is disposed in the backside of an exposure apparatus main body 1, and two stages of chemical filters 31, 32 are disposed near the air intake port 2 in the exposure apparatus main body 1. The two stages of chemical filters 31, 32 reduce a concentration of impurities in a gas of an air conditioning system.
An optical system area 4 on a downstream side of the chemical filters 31, 32 includes various optical members. The exposure apparatus main body 1 includes a laser beam source 5. An exposure laser beam a emitted from the laser beam source 5 is applied to the optical members in the optical system area 4.
In the exposure apparatus main body 1, a splitter mirror 6 is disposed on an optical path of the laser beam source 5, and a life detection optical component 7 made of SiO2 or a fluorite is disposed on a reflection optical path of the splitter mirror 6. The splitter mirror 6 transmits the exposure laser beam a emitted from the laser beam source 5 through the optical system area 4, and splits and applies a part of the laser beam a to the optical component 7.
An air discharge tube 8 (guiding member) is disposed from a downstream side of the first-stage chemical filter 1 toward the chemical component 7. The air discharge tube 8 is provided with a pump 9. Accordingly, a gas on the downstream side of the chemical filter 31 whose life is to be detected is guided through the air discharge tube 8 to a surface of the life detection optical component 7 to be discharged to the same.
A transmittance measurement device 10 is disposed near the optical component 7 in the exposure apparatus main body 1. The transmittance measurement device 10 includes a mechanism of automatically and periodically measuring a transmittance of the laser beam from the splitter mirror 6 through the life detection optical component 7 or a transmittance of light from a transmittance measurement light source 11 through the optical component 7.
In the exposure apparatus configured in the aforementioned manner, upon suction of an external gas from the air intake port 2 into the exposure apparatus main body 1, the gas flows through the two stages of the chemical filters 31, 32 into the optical system area 4 to circulate in the exposure apparatus main body 1. A part of the gas passed through the first-stage chemical filter 31 is drawn through the air discharge tube 8 by an operation of the pump 9, and discharged from the air discharge tube 8 to the surface of the optical component 7.
When a removal rate of the chemical filter 31 drops to increase a concentration of impurities on the downstream side thereof, impurities in the gas discharged to the surface of the optical component 7 become substances of fogging the optical component 7 (fogging substances) by a laser beam applied to the optical component 7 to stick to the component surface. As a result, the transmittance of the optical component 7 drops.
The transmittance measurement device 10 periodically monitors the transmittance of the optical component 7 to plot a graph in which the abscissa indicates time and the ordinate indicates transmittance values. The transmittance measurement device 10 is set to display an alarm when the transmittance becomes equal to or less than a set value or when an absolute value of a change rate of the transmittance becomes equal to or more than a set value.
According to a general exposure apparatus, chemical filters are fixed in both of an air intake port and an air circulation path. According to the embodiment, however, by discharging the gas on the downstream side of the first-stage chemical filter 31 installed at the air intake port 2 to the optical component 7, the life of the first-stage chemical filter 31 can be detected. At this point of time, as the second-stage chemical filter 32 normally retains sufficient removal efficiency, no fog occurs in the optical system in the exposure apparatus main body 1. Thus, if the chemical filter 31 is changed at this stage, maintenance of the optical system is unnecessary. As the first-stage chemical filter 31 alone has to be changed, the work is easy, and an influence on the operation time of the apparatus can be reduced.
As the laser beam applied to the monitor optical component 7, not the exposure laser beam but light split for calibration in the exposure apparatus main body 1 can be used at timing when no calibration is carried out. A lamp (light source for transmittance measurement) 11 for applying light with a wavelength equal to that of light used for an exposure process may separately be disposed in the exposure apparatus main body 11 to apply light therefrom to the optical component 7. The monitor optical component 7 should preferably be installed in a return area of the air conditioning system in the exposure apparatus.
To fog the monitor optical component 7 more efficiently and quickly, the laser beam from the splitter mirror 6 may be applied to the optical component 7, and the light from the lamp 11 may be applied to the optical component 7 for transmittance measurement thereof. In this case, the laser beam from the splitter mirror 6 is used for expediting photoreaction of fogging, and the light from the lamp 11 is used for evaluating the transmittance. The laser beam from the splitter mirror 6 is always applied, or applied during exposure. As photoreaction depends on wavelengths of light components, when no exposure laser beam is used, a laser beam source for generating a laser beam with a wavelength equal to that of the exposure laser beam, or a lamp which includes light components with many equal wavelengths may be used. Transmittance measurement may be periodically carried out (e.g., daily), and light may be applied from the lamp 11 only during the measurement. A wavelength of light from the lamp 11 is basically equal in wavelength to the exposure laser beam. However, light with another wavelength can be used as long as there is a correlation with a transmittance change in the exposure laser beam.
By increasing an air discharge flow rate, the detection sensitivity can be increased, and thus the life of the chemical filter can be detected at an early stage.
When a laser beam from a laser beam source 5 is used as laser beams to be applied to the optical components 71, 72, a part of an exposure laser beam a emitted from the laser beam source 5 is split by a splitter mirror 5 and a light splitter component 110 to be applied to the optical components 71, 72. The transmittance measurement device 101, 102 include mechanisms for automatically and periodically measuring transmittances of laser beams from the light splitter component 110 through the optical components 71, 72 for life detection or transmittances of light components from the lamps (light sources for transmittance measurement) 111, 112 through the optical components 71, 72 to monitor transmittance values.
As shown in
When a plurality of chemical filters are installed in an exposure apparatus main body 1, as shown in
According to the second to fourth modified examples, without disposing a laser beam source, a lamp, an optical component for life detection, or a transmittance measurement device in the exposure apparatus, by simply installing a life monitor of an external unit, the life of a chemical filter can be detected.
According to the embodiment, the gas on the downstream side of the chemical filter is guided through the air discharge tube 8 to the optical component 7. However, a configuration can be employed in which the air discharge tube 8 is removed by arranging the optical component 7 near the chemical filter to be exposed to the gas on the downstream side of the chemical filter in the exposure apparatus main body 1.
As apparent from the foregoing, the embodiment provides the exposure apparatus which includes the mechanism for monitoring the life of the chemical filter used for the air conditioning system in the exposure apparatus. The monitor optical component is disposed in the exposure apparatus, light split from the exposure light source is applied while the gas is applied from the downstream side of the chemical filter to the component surface. The mechanism for measuring a transmittance of the monitor optical component is provided to monitor the transmittance.
When the removal rate of the chemical filter drops, and the concentration of impurities in the gas on the downstream side of the chemical filter increases, the monitor optical component is fogged to reduce a transmittance. Accordingly, by monitoring a change in the transmittance of the optical component, the life of the chemical filter can be detected.
The exposure apparatus of the embodiment facilitates detection of the life of the chemical filter mounted in the air conditioning system in the exposure apparatus. Before damage such as fogging of the process optical member of the exposure apparatus occurs, the life of the chemical filter is detected to enable determination of exchange timing. Thus, the cost of changing the optical component can be reduced, and a drop in operation rate of the exposure apparatus caused by maintenance such as changing or cleaning of the optical component can be prevented. According to the exposure apparatus which includes the two-stage chemical filters, by monitoring the life of the filter of the first stage (upstream side), the apparatus can be operated only by changing the filter of the first stage, and changing time and cost can be reduced.
Conventionally, life evaluation has been carried out by measuring concentrations of impurities in gases on upstream and downstream sides of the chemical filter. Thus, the measurement has needed much time, labor and cost, and much time has passed before a result of the measurement is obtained. According to the embodiment, however, the life detection can be carried out in real time without much time and labor, and without great cost.
According to the embodiment, it is possible to provide an exposure apparatus and a semiconductor device manufacturing method which can easily detect a life of the chemical filter used for an air conditioning system in the exposure apparatus.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-142035 | May 2006 | JP | national |
