| 摘要 |
Positional information of each of wafer stages during exposure and during alignment is measured directly under a projection optical system and directly under a primary alignment system, respectively, by a plurality of encoder heads, Z heads and the like, which a measurement bar placed below surface plates has, using gratings placed on the lower surfaces of fine movement stages. Consequently, high-precision measurement of the positional information of the wafer stages can be performed.
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