In turn, the photoresist hardens in desired patterns when it is developed. During the etching process , wafers are moved to a plasma reactor where electrically excited gases etch the surface into the pattern defined by the photolithography process. After etching, wafers are cleaned thoroughly. Toward final wafer fabrication , each wafer is subjected to testing to determine defective components. Silicon nitride, a protective coating, is applied.
Wafers are then ready for the final processing step, multiprobe testing.