The Need of Top Anti-reflective Coating Materials for ArF Immersion Lithography

Abstract

Recently, a new technology called ArF immersion lithography is emerging as a next generation lithography. The first problem of this technology is contamination issues that come from the dissolution of contaminants from the photoresist to the immersion liquid. The second is optical problem that comes from the using hyper NA system. To solve these two problems, we have developed top antilective coating (TARC) material. This TARC material can be coated on resist without damage to the resist property. In addition to, this TARC material is easily developable by conventional 2.38 wt% TMAH solution. The reflective index of this TARC is adjusted to 1.55, so it can act as an antireflective material. To this TARC material for immersion, quencher gradient resist process (QGRP) was applied also. As a result, we could improve resolution and process margin. However, some of resists showed defects that were generated by this TARC material and QGRP. To solve this defect problem, we introduced buffer function to the TARC material. Thanks to this buffer function, we could minimize defects of resist pattern in immersion lithography.