Michael G. Ury

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.

Microlithography Techniques Using A Microwave Powered Deep UV Source

A number of multilevel resist processes are being developed to solve the difficult problem of producing submicrometer circuit features over profiled surfaces. The application of a novel illumination system, comprising a microwave powered source and catadioptic optical system, to accomplish the pattern transfer step through planarization resists by deep UV flood exposure is characterized. The microwave powered lamp generates 114 watts of deep UV (200 - 260 nm) with an efficiency of greater than 9%. Data showing an effec-tive bulb lifetime of 500 hours or more is presented. Optical filtering techniques are described which effectively attenuate energy above 245 nm and result in excellent critical dimension control. Enhancing areas of the deep UV spectrum by using microwave powered bulbs with additive materials such as cadmium is discussed, and spectral data presented. Problem areas for successful use of the PCM process in production are defined and solutions are discussed. Finally, extensions of microwave powered deep UV lamp technology to other areas of microlithography are discussed.