Patent ID: 6635578
Filing Date: 2003-10-21
Classification: H01J,H01L

Abstract:
A method of operating a plasma reactor having a main chamber for containing a process gas and for holding a semiconductor wafer to be processed, a bias power applicator for applying RF bias power to the wafer and a main plasma source power applicator for applying main chamber plasma source power to the main chamber, and a secondary chamber capable of forming, from a secondary chamber process gas, neutral species furnished to said main chamber, and a second plasma source power applicator for applying secondary chamber plasma source power to said secondary chamber, said method comprising:applying main chamber plasma source power to said process gases in said main chamber by said main plasma source power applicator to produce a first plasma in said main chamber; applying secondary chamber plasma source power to said process gases in said secondary chamber by said second plasma source power applicator to produce a second plasma in said secondary chamber; applying RF bias power to the wafer by said bias power applicator; selecting an increase in neutral species density in said main chamber; selecting a secondary chamber plasma source power level; preventing charged particles formed in the secondary chamber from entering the main chamber by interposing a charged particle filter between the main and secondary chambers, whereby said secondary chamber is primarily a neutral species source to said main chamber for independent control of ion and neutral species densities in said main chamber; and finding an upper limit of the main chamber plasma source power level below which said secondary chamber plasma source power level results in at least the increase in neutral species density in said main chamber selected in the first step of selecting, and maintaining said main chamber plasma source power level below said upper limit.