Technologie von kompakten Excimerlasern

Excimer lasers are pulsed gas lasers. Depending on the gas mixture laser emission is generated on single lines in the UV and VUV portion of the electromagnetic spectra. These emission lines are at wavelengths between 355 nm and 157 nm. The pulse length is normally 5 - 20 ns. Compact Excimer lasers typically have single pulse energy of 10 mJ. The maximum repetition rate is 1 kHz in the compact class. Large Excimer lasers can operate with repetition rates less than 300 Hz, but with single pulse energies up to 1 J. The laser emission is initiated by a pulsed electrical discharge in high pressure gas, having a mixture of rare gases and a halogen. The materials of the laser vessel must be resistant against the Fluorine, or Chlorine. Contaminations must be avoided during assembly and operation of the laser system. Therefore, the newest generation of Excimer lasers is completely metal sealed. All surfaces of the laser vessel - which are exposed to the corrosive laser gas-are s pecially cleaned and partly coated. By introducing this new technique in the past decade, the lifetime of the laser chamber rose from approximately hundred million pulses up to 10 billion and more. Main applications of compact Excimer lasers are the ophthalmology, the vision correction (LASIK), and metrology for semiconductor manufacturing. Large Excimer lasers are used in industrial applications like surface treatment and as light source in wafer steppers producing highly integrated processors and memory chips.