Photoresist Processing Trouble-Shooting Etchants and Solvents
Photoresists Ancillaries Storage/Handling/Ageing Substrate Pre-Treatment and Coating Baking Steps Exposure Development Coating and Lift-off Etching and Stripping
Exposure Wavelengths, Spectral Sensitivities, Doses Rehydration Exposure Dose: Too low/too high? Bleaching Resolution Limits Some Chemistry: The Photoreaction
The photo reaction lowers the UV absorption coefficient of DNQ-based photo resists by several orders of magnitude: Photo resist bleaches and becomes transparent below approx. 440 nm wavelength. For this reason, in exposed resists, the penetration depth of short wavelength light strongly increases, corresponding to a self-energized light-channelling. Beside the possibility to expose thick resist films (penetration depth of i-line in unexposed photo resist only approx. 1-2 micron!), this channelling allows a lateral resolution limit below the theoretical diffraction limit in the resist volume.
Weiterführendes Dokument (pdf) Literature: Exposure and Development  The Photoreaction Weiterführendes Dokument (pdf) Absorption Coefficients of selected Photoresists
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Ancillaries ( developers, thinner, adhesion promoter such as HMDS, remover)
Etchants (acids and the ready-to-use etching mixtures aluminium etch, chromium etch, gold etch und silicon etch)
Solvents (acetone, isopropyl alcohol, MEK ... in VLSI and ULSI quality)