Metal etch with HI-addition to conventional chemistry

The photoresist selectivity is known to increase by changing from chlorine- to bromine-based etchants. Therefore, skipping to iodine-based etchants should result in further enhancement of photoresist selectivity. This is corroborated by a very high photoresist selectivity of the iodine-based etchant HI. Since HI is also the only iodine containing compound with a sufficient vapor pressure for plasma etching, HI should be the etchant of choice for a new aluminum etch process.