The Study on Characteristics of Deep-UV Chemically Amplified Photoresist
When exposure system has advanced from I-line to Deep-UV, traditional Diazo-Novolak photoresist can not be used because of very low transmittance in Deep-UV wave length region. Chemically amplified resist (CAR) could improve the deficiency of lower transmittance, besides, CARs have high sensitivity, good resolution and high contrast, and are the major resist of Deep-UV exposure system. In this thesis, UV spectrometer was used to study the kinetic model of negative-tone chemically amplified photoresist, the change of absorbance of chemically active groups in photoresist were measured as the basis of kinetic reaction study. The thesis contains two parts: 1.Kinetic model: reaction mechanisms were based on the photoacid catalyzed reaction by post exposure bake and photoacid loss reaction. The photoacid catalyzed reaction rate constant, acid loss rate constant and photoacid catalyzed reaction order were obtained by experiments and their physical meanings were studied. 2.Environmental stability: between the exposure and PEB, post exposure delay, the contaminations in air diffusion into the negative-tone resist and induce-the round top profile. The paper studied the photoacid loss by the artificial NH3 contamination and tried to use weak acid to prevent this basic contamination. Chemically amplified resists are the main trend of resist to get into 0.25 micron processes. The kinetic model can be understood further from this thesis. This thesis also proposed the using of weak acid to neutralize basic contamination during post exposure delay.
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