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
Photoresists Ageing of Photoresist Developer
The ageing of developers (=aqueous alkaline solutions) originates from CO2-absorption from air, decreasing the developer activity and the development rate. Therefore, we recommend a storage in well-closed original containments. In case of open developer baths over a period of several days, a N2-stream minimizes the CO2-absorption.

Certain developers (e.g. AZ® 400K, AZ® 351B) contain chemical buffers which enable a constant development rate over a long time span as compared with simple NaOH/KOH solutions.
 Overview: Developer (Metal Ion containing)  Overview: Developer (Metal Ion free)
MicroChemicals® - All you need for microstructuring with short lead times also in small sales volumes:

Photoresists (positive, negative, image reversal, thin and thick resists, spray resists, protective coating ...)
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)