EFFECT OF HYDROGEN ACCEPTORS ON PK(A) OF PHENOLIC RESINS - LINK TO DISSOLUTION INHIBITION

Dissolution inhibition in positive resists is brought about by an indu ctive polarization effect of strong hydrogen accepters, which creates hydrogen-bonded strings of OH groups. The acidity of the OH groups bou nd in the strings is considerably lower than that of phenols in the bu lk of the system. It is the reduction in the concentration of protons in equilibrium with the various parts of the resin that lowers the rat e of phenol deprotonation and with it the rate of resin dissolution. H ere we describe changes in the pK(a) of the resin in the presence of h ydrogen accepters (dissolution inhibitiors) and we demonstrate the exi stence of a quantitative link between acidity changes and inhibition f actors.