Cleaning of substrates When new and clean substrates (wafers) are used, a heating at approximately 200 °C for several minutes (2-3 min, hot plate) is sufficient for drying. Substrates should however subsequently be processed quickly.
Process procedure e-beam resist
Development of PMMA films PMMA films can only be developed with solvent-based developers. Aqueous-alkaline PMMA developers will not attack PMMA – PMMA is even used as protective coating in the presence of strongly alkaline solutions (
Process conditions
Gas bubbles during coating Air bubbles often occur when resist bottles are e.g. shaken or moved around before coating, or if a resist is diluted. They may also appear if the coating step is performed immediately after opening of the resist bottle,
Photoresists are light-sensitive, their properties change in the presence of light or elevated temperatures. Resists age during storage and are therefore supplied in light-protected amber glass bottles,