The PEB process causes three effects: (1) the diffusion of the PAC, (2) solvent evaporation and, (3) thermally induced chemical reactions. The influences of these mechanisms on the average dissolution rate of the resist are not easily segregated from one another when reflective substrates are used. The effect of standing waves was eliminated by using nonreflective substrates. The effects of the solvent removal and other thermal reactions on the dissolution rates of the resist were investigated at different PEB temperatures concentrating on two different resist systems. In general, the dissolution rates of both resists decreased as a function of the PEB temperature. The magnitude by which the dissolution rate changes with PEB temperature at different exposure energies depends on the resist composition and its chemistry at elevated temperatures. The steepness of DRM average bulk dissolution rate curves generated on nonreflective substrates suggest improved resist performance without PEB. In practice, however, high contrast resists processed without PEB, on non-reflective substrates have poorer lithographic performance than when using a PEB. Accurate analysis of the dissolution rate data revealed that the surface dissolution inhibition caused by the PEB is responsible for the improvement.