| abstract |
A process for etching multiple layers (22, 24) on a substrate (25) in an etching chamber (30) and cleaning a multilayer etchant residue formed on the surface of the walls (45) and components of the etching chamber (30). In multiple etching steps, process gas comprising different compositions of etchant gas is used to etch layers on the substrate (25) thereby depositing a compositionally variant etchant residue inside the chamber (30). In one cleaning step, a first cleaning gas is added to the process gas to clean a first residue or to suppress deposition of the first residue onto the chamber surfaces. In a second cleaning step, another residue composition is cleaned off the chamber surfaces using a second cleaning gas composition. The process is particularly advantageous for etching of metal silicides (22) or polysilicon (24) using chlorine or bromine chemistry, whereby fluorides like CF4, NF3 or SF6 are added as first cleaning gas, and oxygen is used as second cleaning gas. |