| 摘要 |
PURPOSE:To carry out a stable exposure for a long term by preventing the wear of an electrode by effecting a switching from a low-power step to a high-power step in a mercury lamp under the condition that 95% of the level is attained in 1-30msec. CONSTITUTION:A shutter 4 is in an open state only for the predetermined time under the condition that a mercury lamp 1 has been lighted during the first step A in which an electric power consumption becomes high level. The condition is shifted to one that the mercury lamp 1 is lighted during the second step B in which the power consumption becomes low level, during which the shutter 4 is closed. The exposure is effected by relatively combining the first and second steps A and B, opening and closing operations of the shutter 4, and the step shift of a material 2 of a semiconductor wafer. Swiching of the step from B to A is effected under the condition that the power consumption of the mercury lamp 1 reaches 95% of the high level in the step A in 1-30msec. Consequently, the early wear of an electrode of the mercury lamp can be prevented. |
