Dry cleaning uses plasma-based processes to remove organic contamination and residues without wet chemicals. Mechanism: Plasma generates reactive species (oxygen radicals, ions) that react with organics, converting them to volatile products (CO2, H2O). Common plasmas: O2 plasma (ashing), H2 plasma (native oxide removal), N2/H2 (gentle clean), Ar (sputtering). Applications: Photoresist ashing and stripping, post-etch residue removal, surface preparation, descum. Advantages: No wet chemical waste, environmentally friendly, can reach small features, vacuum compatible. Photoresist ashing: O2 plasma converts photoresist to CO2 and H2O. High throughput. May damage some materials. Residue removal: Post-etch polymer removal, sidewall clean. Critical for high aspect ratio features. Downstream plasma: Remote plasma generation reduces damage to sensitive devices. Damage concerns: Plasma can damage gate oxides, introduce charging. Careful recipe required for sensitive structures. Integration: Often used in combination with wet cleans for complete contamination removal. Equipment: Plasma asher (barrel or downstream), RIE-style tools for more control.