Advanced micro-lithography process for i-line lithography

In our previous paper [Jpn. J. Appl. Phys. 40 (2001) 419], we reported the development of an advanced micro-lithographic process for producing 0.1 mum contact holes by KrF excimer laser (248 nm) lithography. This chemical shrinkage technology, called resolution enhancement lithography assisted by chemical shrink (RELACS), utilizes the cross-linking reaction catalyzed by the acid component remaining in a predefined resist pattern. We report herein the results of the application of RELACS to i-line (365 nm) lithography. The properties of RELACS for i-line lithography were very, different from those for KrF lithography. This is due to the difference in chemical mechanism between i-line and KrF resists. The characteristics of the application of RELACS to i-line lithography were studied by conducting basic experiments on the addition of a photo-acid generator (PAC) to an i-line resist and investigating the property of the cross-linking reactions involved in the pre-doping of various acids to RELACS film. Finally, we optimized RELACS materials to match i-line resist and realized the fabrication of contact holes less than 0.2 mum diameter by i-line lithography.