Polysilicon Multistep Etching Process in Radial-Flow Anode-Coupled Reactor
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
Sequential multistep plasma etching of polysilicon allows to achieve better control of desired etched profiles, wafer and batch etch rate uniformities in radial-flow plasma reactor. This three-step etch process has been developed to combine the advantages of different chemistries. STEP 1 A CF4 Ar plasma at high power clears the polymer residues, left by a photolithographic process, by carbon and fluorine recombination reaction. This step is needed to insure wafer etch-rate uniformity during the second step. STEP 2 A CF4 CO2 plasma provides fast isotropic polysilicon etching, good uniformity and lower resist loss for a better etched profile without the barrel shape observed with CF4 O2 plasma.