ArF excimer laser device for exposure

An ArF excimer laser comprising a laser chamber filled with laser gases composed of fluorine gas, argon gas and at least one rare gas other than argon gas and a high voltage pulse generating device which generates pulses within the laser chamber of reversed polarity having an electrical discharge oscillating current waveform for exciting said laser gas and acting in conjunction with an optical system for discharging a series of laser beams so as to perform an oscillating current waveform laser operation with a repetition rate of more than 3 kHz;

• wherein, to produce a laser pulse with a width of at least 30 ns;
• the laser operation is carried out in a start half-period of the electrical discharge oscillating current waveform of the pulses generated by said high voltage pulse generating device and in at least two subsequent half-periods;
• a pressure of said laser gas in the laser chamber is from 2.5 to 3.5 atm;
• a concentration of the fluorine in said laser gas is 0.12% or less of the volume of the laser gas;
• and
• a concentration of the argon gas in said laser gas is from 2% to 3% as a partial pressure of the argon gas relative to the pressure of the laser gas in the laser chamber.