Development of positive photoresist

A new model is proposed to describe the development of positive photoresist over the full range of exposure. The model includes the depth dependence of development rate and is capable of fitting measured data of all resists examined to date. A measurement system for determining the exposure and development model parameters is described. Several types of photoresist and developer have been characterized under a number of processing conditions. The effect of the development model parameters on developed resist profiles is illustrated using simulation.