| abstract |
A plasma reactor for processing a workpiece such as a semiconductor wafer has a housing defining a process chamber, a workpiece support configured to support a workpiece within the chamber during processing and comprising a plasma bias power electrode. The reactor further includes plural gas sources containing different gas species, plural process gas inlets and an array of valves capable of coupling any of said plural gas sources to any of said plural process gas inlets. The reactor also includes a controller governing said array of valves and is programmed to change the flow rates of gases through said inlets over time. A ceiling plasma source power electrode of the reactor has plural gas injection zones coupled to the respective process gas inlets. In a preferred embodiment, the plural gas sources comprise supplies containing, respectively, fluorocarbon or fluorohydrocarbon species with respectively different ratios of carbon and fluorine chemistries. They further include an oxygen or nitrogen supply and a diluent gas supply. The controller is programmed to produce flow of different process gas species or mixtures thereof through different ones of said plural gas injection zones. The controller is further programmed to change over time the species content of the gases flowing through different ones of said plural gas injection zones. |