Characterization of latent image by surface energy determined by contact angle measurements

Abstract

The resist processes used for optical lithography are mainly positive tone, based on the use of DNQ/novolac photoresists. The decrease in feature size requires a good knowledge and control of each step. The formation of the latent image is one of the more critical steps as it is very difficult to control and the quality of the subsequent steps is mainly governed by the quality of this image. This paper proposes to use contact angle measurements to follow resist surface modifications occurring during exposure. This technique leads to the determination of the different components of the surface energy. The correlation between Fourier transform infrared analysis and surface energy components has shown that contact angle measurements allow the latent image formation to be followed.