Cadmium/rare gas discharge lamp of the short arc type, as well as projection exposure device using the same

Abstract

A cadmium/inert gas discharge lamp of the short arc type, which suppresses an unnecessary emission upstream and downstream of the necessary emission spectra in a wavelength range of 210 to 230 nm, achieves a high efficiency of the emission spectra in the range 210 to 230 nm and can be used in very satisfactory manner for industrial applications. Also, a highly efficient projection exposure device through the incorporation of a cadmium/rare gas discharge lamp of the short arc type having good emission spectrum characteristics in the wavelength range 210 to 230 nm, which can transmit in projecting manner fine image patterns with a large depth of focus. The cadmium/rare gas discharge lamp of the short arc type is arranged within a temperature-regulated quartz bulb, and is provided with a pair of adjacently facing electrodes, together with inert gas selected from xenon, krypton, argon, neon or mixtures of them. Metal cadmium with a pressure of 14 to 200 kPa is encapsulated in the tube in a stationary lighting operation. The lamp is operated in such a way that J/P, i.e. the ratio between a discharge current in a stationary lighting operation J (A) and a cadmium pressure in a stationary lighting operation P (kPa) is in a range 0.13 to 15. Also, a projection exposure device, which has the above-described discharge lamp and a power supply for carrying out the lighting operation of the discharge lamp under the above-described condtions.

Dependencies are inferred from the claim text.