Etching titanium nitride and silica at a similar rate, when making numerous interconnection terminals or pads in DRAM is carried out in vacuum chamber in controlled flow of nitrogen fluoride

摘要

Silicon wafer is structured with a metallic base layer and an upper insulating layer of silica. This is covered by a metallic contact, formed by a layer of titanium nitride covered by Al-Cu. The wafer is placed on the electrostatic chuck of the vacuum chamber of the etching unit. Power applied is less than 400 W. A flow of NF3 gas is directed onto the structure at 40 sccm, so the selectivity ratio SiO2:TiN is about 4. Further preferred methods based on the foregoing procedure are also described.