Exposure apparatus

#The present invention relates generally to a projection exposure apparatus used for the photolithography process, and more particularly to an exposure dose control in the scanning exposure apparatus.

#A projection exposure apparatus that employs a projection optical system to expose a reticle (mask) pattern onto a wafer has been conventionally used. A scanning exposure apparatus has recently been reduced to practice for wide-screen exposure. The precision required for a pattern's critical dimension (“CD”) uniformity becomes stricter as the fine processing develops.

#In order to reduce the uneven illuminance on the screen that aggregates the CD uniformity, the conventional scanning exposure apparatus controls the exposure dose using a light blocking plate near a scan masking blade that defines an illumination area or slit. For example, the exposure dose around the light blocking plate is set to be larger when the optical system has a higher transmittance at the center of the optical axis than at the periphery.

#FIG. 1 is a scanning exposure apparatus according to one aspect of the present invention.

#FIG. 2 is a partially enlarged sectional view of an illumination optical system in the exposure apparatus shown in FIG. 1.

#FIGS. 3A and 3B are schematic plane views of uneven-illuminance correctors shown in FIG. 2. FIG. 3C is a schematic plane view showing a relationship between the slit irradiated onto a reticle shown in FIG. 2 and the scanning direction.

#Referring now to the accompanying drawings, a scanning exposure apparatus 100 according one aspect of the present invention. Here, FIG. 1 is a schematic sectional view showing a structure of the exposure apparatus 100. The exposure apparatus 100 is a scanning exposure apparatus that exposes a circuit pattern of a reticle 200 onto a wafer 400 in a step-and-scan manner. The exposure apparatus 100 includes, as shown in FIG. 1, an illumination apparatus 110, a reticle stage 210 that supports the reticle 200, a projection optical system 300, a wafer stage 410 that supports the wafer 400, a measurement apparatus 500, and a control system 600.

#The illumination apparatus 110 illuminates the reticle 200 that has a circuit pattern to be transferred. The illumination apparatus 110 includes a light source unit 120, and an illumination optical system (130, 140).

#The light source unit 120 uses, as a light source, an ArF excimer laser with a wavelength of approximately 193 nm in this embodiment. However, the light source unit 120 is not limited to the ArF excimer laser, and may use, for example, a KrF excimer laser with a wavelength of approximately 248 nm, and an F2 laser with a wavelength of approximately 157 nm.