Model studies on the metal salt sensitization of chemically amplified photoresists (Conference Presentation)

As EUV approaches its insertion point into high volume manufacturing the semiconductor industry is increasingly focusing on photoresist performance. Recently metal containing resists have been proposed as alternatives to standard Chemically Amplified (CA) systems. Both approaches suffer from an incomplete knowledge of the EUV imaging mechanism. In particular the origin, number and fate of the secondary electrons believed to be active in the resist reactions is poorly understood. In this contribution we describe a study designed to try and characterize these processes and quantify the reactions that determine resist performances. We will describe experiments on a series of model CA systems doped with inorganic salts. Photoacid yields and relative rates of deprotection will be reported for metal salts that can be incorporated into polymer films at concentrations as high as 10 molal. In addition to comparing the relative performance at EUV we will also be characterizing the response at 248 nm and 100 KeV e beam. The results of these studies will be discussed in terms of the metal ion crossection, ionization potential and redox potential. In addition we will describe some unanticipated EUV reactivity of standard acid indicators that may impact the accepted electron yield/photospeed measurements that have been reported for EUV CA resists.