Using interdigitated electrodes for measuring photoacid generator kinetics in chemically amplified resists

In this work, the feasibility of using interdigitated electrodes to measure the kinetics of photoacid generation in a resist film has been examined. Interdigitated electrodes provide a quick, noninvasive, nondestructive alternative to traditional Dill C measurement techniques and unlike traditional techniques is easily performed in a wafer fab environment. The initial results indicate that the interdigitated electrodes (IDEs) used in this work are capable of both detecting the small quantities of acid generated by photoacid generators (PAGs) at loadings typical of those found in chemically amplified resists and quantifying the amount of acid generated during exposure. In addition, a linear relationship has been observed between measured IDE capacitance and both PAG and photoacid content. This relationship has been utilized to determine the Dill C parameter from the measured IDE capacitance response vs. exposure dose for films consisting of triphenylsulfonium triflate (TPS-Tf) in a poly(hydroxystyrene) (PHOST) matrix. A Dill C value of 0.0445 cm(2)/mJ was measured for TPS-Tf in PHOST, which is in agreement with literature values for similar PAG-polymer systems. (C) 2004 The Electrochemical Society.