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.
Each integrated circuit in the wafer is electrically tested to determine whether or not a chip is ready for final assembly, bonding and packaging.