| 摘要 |
PCT No. PCT/JP89/00080 Sec. 371 Date Nov. 22, 1989 Sec. 102(e) Date Nov. 22, 1989 PCT Filed Jan. 27, 1989 PCT Pub. No. WO89/07353 PCT Pub. Date Aug. 10, 1989.A method for controlling a narrow-band oscillation excimer laser which is suitable for control of an excimer laser used as a light source of a reduced projection exposer, and a system thereof. At least two wavelength selective element are disposed within a laser oscillator. There are provided a center wavelength control for causing an oscillation center wavelength determined by these wavelength selective elements to coincide with a desired value, an overlapping control for overlapping the transmission wavelengths of these wavelength selective elements, and a power control for controlling a voltage applied to electrodes located within a laser chamber to thereby control a laser output. Partial gas replacement is carried out when the application voltage to the electrodes within the laser chamber becomes high. After execution of the partial gas replacement, such control is carried out that the control period of the overlapping control is set to be substantially equal to that of the power control or that the overlapping control is inhibitd during the power control. At the time of activating the laser, the overlapping control is first carried out and then the center wavelength control is carried out.
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