| The so-called Meyerhofer plot opposites the alkaline solubility of unexposed and completely exposed photo resists as a function of the photo active compound concentration. Before exposure, the inhibitor DNQ-sulfonate decreases the development rate by 1-2 orders of magnitude, which is similar to the development rate increase caused by the product of the photo reaction, the indene carboxylic acid.The dependency of the exposure dose from the development rate of a thin (illumination penetration depth > resist film thickness), and a thick (penetration depth < film thickness) photo resist is different: From a certain exposure dose on, the photo active compound is sufficiently converted into the indene carboxylic acid to allow a constant high development rate in thin films. The impact of bleaching becomes clearly visible for thick resist films: Below a certain exposure dose, the resist cannot be cleared. |
Literature: Exposure and Development
The Photoreaction