Improved Resolution of Thick Film Resist

摘要

The effect of pre-baking conditions on the resolution and aspect ratio of thick-film resists is examined in order to improve resist processing performance. Resist samples are pre-baked at various temperatures and for various baking times, and a range of resist properties are examined. It is found that the pre-baking conditions affording the best resist pattern profile and development contrast are 125°C for 7 min. The mechanisms responsible for the observed variations in pattern profile are studied by comparing and simulating the development activation energy, the change in the amount of solvent and photo active compound (PAC) during pre-baking, the residual solvent amount in the resist, and the transmission after pre-baking. The results indicate that there are two factors responsible for retarding the pattern formation process and causing degradation of pattern profile and resolution. One mechanism is N_2 bubbling during development, which is caused by N_2 trapped in residual solvent during exposure. The other mechanism is thermal decomposition of the PAC during baking, which weakens the retardation of development unexposed resist.