Gel layer model for photoresist development

The positive photoresist is assumed to be transferred, via intermediate gel state, from the resist to the developer solution. A mechanism for the development of positive photoresist is proposed to derive a development rate equation considering gel layer formation. This new model using the concept of gel layer can better fit recent experimental dissolution rate data exhibiting a notch shape which is critical to resist performance. The model parameters are obtained by fitting measured dissolution data using the least square method. The variation of gel layer thickness during dissolution is well explained with the model.