Formation and removal of composite halogenated silicon oxide and fluorocarbon films deposited on chamber walls during plasma etching of multiple film stacks

A study was conducted on the chemical nature of the composite films depositing on the reactor walls during STI etching using plasma and surface diagnostics. However, the composite film can be removed by using an O₂ plasma maintained under conditions where the gas residence time was sufficiently high. In this case, the removal of the composite film proceeds by etching of the fluorocarbon film by O in the O₂ plasma, and subsequent etching of the halogenated silicon oxide component of the film by F produced by electron impact dissociation of the fluorocarbon etching products in the gas phase.