Optical monitoring and control system and method for plasma reactors

A plasma processing system for controlling the processing of a substrate with a plasma, the system comprising:

• a) a plasma reactor chamber capable of containing the plasma;
• b) a substrate pedestal for supporting the substrate;
• c) a segmented electrode assembly arranged within said chamber adjacent said substrate, said assembly having a plurality of electrode segments;
• d) a plurality of RF power supplies, each said supply electrically connected to a corresponding one of said electrode segments;
• e) a plurality of fiber optic sensors integrated into said electrode assembly, each of said sensors having first and second ends, said second ends arranged to receive light from respective regions of the plasma and transmit said light to said first ends;
• f) a sensor array system arranged to receive light from said first ends of said fiber optic sensors and to convert said light into an electronic output signal corresponding to the spectral content of said light as a function of position across the plasma;
• and
• g) a control system in electrical communication with said sensor array system and said plurality of RF power supplies, for controlling the RF power to said electrode segments based on said electronic output signal from said sensor array system.

9 An electrode assembly for a plasma reactor system for processing a substrate with a plasma, the electrode comprising:

• a) a plurality of substantially planar electrode segments arranged adjacent one another and arranged to be substantially parallel to the substrate when said segments are installed in the reactor system;
• b) insulating members, arranged between said electrode segments, each having a sensor bore formed therein;
• and
• c) a plurality of fiber optic sensors each having first and second ends, with said second ends held within respective sensor bores such that said second ends receive light from respective regions of the plasma.

An electrode assembly for a plasma reactor system for processing a substrate with a plasma, comprising:

• a) a planar electrode body having upper and lower substantially planar surfaces with a plurality of through-bores having an input end at said upper surface and an exit end at said lower surface;
• b) two or more transparent windows, each arranged at a respective exit end of a respective one of said bores;
• and
• c) two or more fiber optic sensors each having a first end and a second end, with each of said second ends arranged within a corresponding one of said two or more bores adjacent one of said windows.

An electrode assembly for a plasma reactor system for processing a substrate with a plasma, comprising:

• a) an electrode body having a lower surface;
• b) a plurality of adjustable nozzle units arranged along said electrode body lower surface, for controlling the flow of gas through the electrode assembly, each said nozzle unit having a nozzle plug with a tip, and a nozzle bore passing through said nozzle plug and said tip;
• and
• c) a plurality of fiber optic sensors, each held in one of said nozzle bores such that said fiber optic sensors can receive light from the plasma through said tip.

A plasma processing system for controlling the processing of a substrate with a plasma, the system comprising:

• a) a plasma reactor chamber capable of containing the plasma;
• b) a substrate pedestal for supporting the substrate;
• c) a segmented electrode assembly according to claim 9 arranged within said chamber and facing the substrate;
• d) a plurality of RF power supplies, each said supply electrically connected to a corresponding electrode segment;
• e) a sensor array system arranged to receive light from said fiber optic sensors and to convert said light into an electronic output signal corresponding to the spectral content of said light;
• and
• f) a control system in electrical communication with said sensor array system and said plurality of RF power supplies, for controlling the power to said electrode segments from said RF power supplies based on said electronic output signal from said sensor array system.

A method for improving overall plasma processing uniformity of a wafer in a plasma processing system having a plasma and an electrode assembly with a plurality of electrode segments connected to respective RF power supplies, comprising the steps of:

• a) determining a time to an endpoint for each of a plurality of portions of a first wafer using an array of sensors arranged adjacent the plasma and spaced apart in a direction substantially parallel to the wafer;
• b) loading a second wafer to be processed into the plasma processing system;
• and
• c) adjusting RF power delivered to each electrode segment by an amount proportional to differences in said endpoint times.