  The photochemical acid generation is refined from the very first principles
of elementary particle physics. We first briefly review the formulation of the
quantum theory of light based on the quantum electrodynamics framework to
establish the probability for acid generation at a given spacetime point. The
quantum mechanical acid generation is then combined with the deprotection
mechanism to obtain the probabilistic description of the deprotection density,
directly related to the feature formation in a photoresist. A statistical
analysis of the random deprotection density is presented to reveal the leading
characteristics of stochastic feature formation.
