EXCIMER LASER SOURCE SYSTEM IN WHICH FREQUENCY FOR HIGH RESOLUTION PROJECTION TYPE LITHOGRAPH IS STABILIZED AND LINE WIDTH IS NARROWED

摘要

PURPOSE: To form radiation light having a narrow spectrum band width together with a central wavelength equipped with high-order stability by comparing an excimer laser wavelength with a basic absorption line while using three different optic/dynamic stabilizing loops. CONSTITUTION: A cell 20 is inserted into a laser void specified by mirrors 14 and 16. A piezoelectric transducer 18 is driven so as to optimize a laser void interval between the mirrors 14 and 16. A piezoelectric transducer 42 is driven so as to maximize a detector signal again by precisely adjusting the void interval of a resonator 34 when the intensity of a beam 35 emitted from the resonator 34 is deviated from an optimum value. A piezoelectric transducer 54 is driven so as to precisely adjust the wavelength of an excimer laser oscillator 44 for maximizing the transmission of a beam 58 to be passed through the resonator 34. A transmitted beam 71 from the oscillator 44 is passed through an amplifier 72 just once and amplified by passing a gain due to induction emission in an excimer discharging gain chamber 73. Thus, high-order frequency stability and narrow spectrum band width can be provided.