The photo active compound of AZ® and TI
photoresists belongs to the group of
diazonaphtho-quinone-sulphonates (DNQ).
Their presence in photoresists reduces the alkaline
solubility by more than one order of
magnitude (Meyerhofer-plot right-hand).
During exposure, the DNQ transforms into a
carboxylic acid, accompanied by the release of
nitrogen and the absorption of water (schema
overleaf). Thus, the alkaline solubility increases
by several orders of magnitude and is
finally more than one order of magnitude
higher as compared to pure Novolak