Measuring Acid Generation Kinetics in Photoresist Films via Capacitance Techniques
Berger, Cody Michael
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In this thesis, a novel technique for measuring photoacid generation kinetics in chemically amplified photoresists was developed that utilizes capacitance measurements from interdigitated electrodes. In this technique, a chemically amplified photoresist is first coated onto the interdigitated electrode sensors. Then, capacitance measurements are recorded from the sensor as the photoresist is exposed to UV radiation. As acid is generated in the film during exposure, the net dielectric constant of the resist film changes, resulting in a change in the capacitance measured from the IDE sensor. By properly analyzing the observed capacitance response to exposure, it is possible to determine the kinetic rate constant for photoacid generation, or Dill C parameter. The discussion in this thesis describes four major areas of work performed. First, the basic development of the Dill C measurement technique and data analysis algorithm is described. Second, potential complications due to relative humidity changes, spin coating problems, and ambient base contamination are investigated. Next, the discussion turns to two key improvements to the measurement technique: the use of multi-frequency measurements to increase the capacitance signal, and the development of a normalized capacitance expression for improved data analysis. Finally, the effects of two critical components of chemically amplified resist solutions upon the technique are studied: protecting groups and background base quenchers.