A buffer gas contained in a laser gas used for an ArF excimer laser mainly
consists of He, and Xe is preferably added to the laser gas. Mixture
piping divided by valves is disposed on piping running from a chamber to
an excimer laser gas cylinder, the mixture piping and a Xe gas cylinder
are connected, gas exhaust by a gas exhaust module and opening and closing
of the valves are controlled by a gas controller to add a trace quantity
of xenon gas to the excimer laser gas. Thus, to remedy a burst
characteristic and a spike characteristic of the ultraviolet laser device
by adding a trace quantity of xenon gas, the xenon gas can be supplied
efficiently into the chamber without modifying existing laser gas supply
equipment.
