Multilevel imaging system realizing k1=0.3 lithography

The pursuit of ultimate resolution by optical lithography has given rise to many new technologies, such as PSM (phase shifting mask), oblique illumination etc. In order to realize the benefit of these new technologies in practice, a new exposure technology IDEAL (Innovative Double Exposure by Advanced Lithography) is proposed. First exposure is for fine patterns, which are imaged with high contrast and large depth of focus, while second exposure is done with multileveled light distribution. These two exposures collaborate each other to form fine patterns with reasonable focus margin and good two-dimensional profile. Experimental results of logic gate patterns are shown and demonstrate the possibility of k(1)=0.3 lithography. Using IDEAL, KrF lithography can be extended to 100-110 nm and ArF to 80 nm resolution.