ASH 210

An asher is semiconductor process equipment used to remove photoresist and other organic residues from wafer surfaces. Ashers are commonly used after lithography and etch steps to clean wafers by exposing them to a reactive plasma that converts resist into volatile byproducts.

Ashers generally operate by generating a low pressure plasma from process gases inside a treatment chamber. Reactive species from the plasma attack organic films on the wafer surface and convert them into gaseous reaction products that are then exhausted from the chamber.

Ashing is typically distinguished from directional plasma etching by emphasizing resist stripping and residue removal rather than pattern transfer. Ashers are often integrated into cleaning sequences where controlled plasma exposure reduces residual polymers before subsequent wet cleaning or inspection.

Ashers sit in the back end of many patterning sequences after the wafer has undergone exposure, development, and an etch or implant related step that leaves photoresist in place. Ashing prepares the wafer for downstream cleaning, inspection, deposition, or additional lithography by removing resist and associated organic contamination.

Ashers are used for photoresist stripping, descum, and post etch residue removal in semiconductor manufacturing. Ashers are also used in process flows that require removal of organic films before later surface preparation or film formation steps.