Basic Performance of VUV Exposure Systems Using Head-on Type Ar2 and Kr2 DBD Excimer Lamps

As an application of dielectric barrier discharge(DBD) lamps, vacuum-ultraviolet(VUV) exposure systems of both Ar2* and Kr2* excimers have been developed and their basic performance has been evaluated. Each system comprises a 20-W DBD excimer lamp, a sinusoidal wave high-voltage power supply, and a cylindrical lamp holder. A high-voltage transformer and a lamp are designed to be set as close together as possible in the holder. The inside of the holder is purged and filled with nitrogen gas when it is in use. The excimer lamp has an MgF2 window at the lamp end and is a “head-on type” lamp. The head-on type Ar2* excimer VUV system produced monochromatic light at 127 nm (with a 9.8-nm FWHM). It’s irradiance had an almost homogeneous distribution within a 15-mm diameter planar circle at 50 mm from the output window and was about 0.4 mW/cm2. The head-on type Kr2* excimer VUV system produced monochromatic light at 147 nm (with a 13.2-nm FWHM). It’s irradiance had an almost homogeneous distribution within a 15-mm diameter planar circle at 50 mm from the output window and was about 1.4 mW/cm2. The lifetime of the lamps in these system is defined as the time point at which irradiance drops to 50% of its initial value. It was 500 and 1500 h, respectively, for the Ar2* and Kr2* excimer lamps.