| abstract |
A dry etching method using no organic resist mask without involving an increase in the number of necessary processes or wafer surface steps. Conventionally, a nitrogen based compound film (6) is formed as a thin anti-reflection film on a gate electrode or aluminum (Al) metallization layer. The nitrogen based compound film (6) thus formed can be used as an etching mask for the material layer by using etching gas capable of forming sulfur (S) in a plasma when dissociated by electric discharges. For instance, a W polycide film (5) masked by a TiON anti-reflection film patterned into a predetermined shape can be etched by S₂F₂ / H₂ mixed gas. In this case, a nitrogen (N) dangling bond formed on the surface of the TiON anti-reflection film (6) combines with sulfur supplied by S₂F₂ to form a polythiazyl (SN) x coating, which provides the resulting TiON anti-reflection film pattern (6) with a sufficient etching resistance to act as an etching mask. This etching process emits no carbon to the etching system, thus improving selectivity for a SiO₂ based material layer. The TiON anti-reflection film pattern (6) can also be used as an etching mask for an aluminum metallization layer with a view to reducing after-corrosion. |