High Density Plasma Etching of Platinum Films in BCl3/Ar and CF4/Ar Inductively Coupled Plasmas

The etch characteristics of platinum films and the etch selectivities for platinum over the mask materials in BCl3/Ar and CF4/Ar ICP discharges have been investigated to establish a process window for the thick platinum structure formation in MEMS devices. Maximum etch rates of similar to 1800 angstrom/minute and similar to 1200 angstrom/minute were obtained at a moderate ICP source power (750 W) and a relatively high rf chuck power (400 W) condition for CF4/Ar mid BCl3/Ar ICP discharges, respectively. Maximum etch selectivities of similar to 2.6 for platinum over Al and of similar to 2.1 for platinum over ZnO were obtained. CF4/Ar ICP etching with aluminum mask layer seems to be a very attractive tool for the fabrication of MEMS devices containing a thick platinum structure layer.