Charles H. Wood

New Deep Ultraviolet Source For Microlithography

An electrodeless microwave powered deep UV source has been developed. This source pro-duces a unique intense spectrum between 190 and 260nm. Deep UV radiated power output efficiencies exceed 10% at microwave power input levels of 1500 watts. The lack of elec-trodes avoids output attenuation due to electrode sputtering that can cause deep UV fall-off and early bulb failure with compact arcs. Optical systems have been designed to utilize this source for effective flood irradiation of wafers with deep UV having good intensity, uniformity and collimation characteristics. One application of this source is to the portable conformable mask (PCM) technique for meeting submicrometer resolution requirements over profiled surfaces. In this application the exposure time to clear a 2 micrometer PMMA layer using the microwave powered deep UV source is less than 30 seconds.