SYSTEM FOR PREVENTING VARIATION OF FOCUS WITHIN EXPOSURE EQUIPMENT

摘要

Purpose: a kind of system is arranged to prevent focus variations and time for exposure within a radiation device, so that exposure performance is improved. Construction: in a radiation device, a shutter (ST) is driven by a servo motor (M), so that a lattice pattern is transferred to a chip by lights via a focusing system. Here, a kind of system for preventing the focus variations in radiation device includes a circuit (20), it is the exposure one shutter driver signal of output with the shutter (ST) of a specific time interval, in a process wait state when chip is not loaded into a wafer stage. Therefore, because process interruption can prevent focal variation in a process wait state, so that exposure performance can be improved.