EXPOSURE AND PATTERNING PROCESS FOR FORMING MULTI-LAYER RESIST STRUCTURES

摘要

A method for forming on a substrate a multi-layer resist structure having a controlled and pre-determined amount of undercut or overcut according to whether a positive or negative tone resist is used. The amount of undercut or overcut is controlled by means of a predetermined level of pre-exposure of each underlying resist layer prior to deposition of the next resist layer and the final patterning of the top resist layer. The multi-layer resist is then developed to remove resist in a controlled manner from each layer according to the degree of exposure of the resist. Using the technique, multi-layer resist structures having very fine sub-micron details may be formed. Multi-layer positive tone resist structures can be employed as a mask and combined with metal deposition and lift-off techniques for fabricating very high resolution metallic features.