Novel Fast Etch Rate BARC for ArF Immersion Lithography

Abstract

Thickness of 193 immersion photoresist (PR) has been continuously reduced to achieve smaller critical dimension (CD) beyond 1x nm nodes. As a result, faster etch rate (E/R) bottom antireflective coating (BARC) is required to maintain appropriate PR thickness as a mask for pattern transfer and small CD bias after dry etch process of BARC. The etch rate of BARC can be theoretically predicted by Ohnishi Parameter (O.P.); faster etch rate can be obtained by high O.P. with increase in number of hydrophilic heteroatoms, such as nitrogen (N) or oxygen (O). However, poor solubility of high polar resin is the major technical barrier in development of faster E/R BARC. We have designed novel polarity-switchable BARC (PS-BARC) with enhanced solubility via hydrophobic protecting groups while maintaining fast etch rate. In this paper, details of BARC new fast E/R immersion BARC for 193 nm lithography will be discussed.