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Diagnostic and Etching Studies of Inductively Coupled Plasmas. SFR Workshop November 8, 2000 Matthew Radtke, John Coburn, David Graves Berkeley, CA. 2001 GOAL: Detection of depositing etch product in Si-O-Cl system by 9/30/2001. Motivation.
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Diagnostic and Etching Studies of Inductively Coupled Plasmas SFR Workshop November 8, 2000 Matthew Radtke, John Coburn, David Graves Berkeley, CA 2001 GOAL: Detection of depositing etch product in Si-O-Cl system by 9/30/2001.
Motivation • Increasingly stringent processing demands require • better fundamental understanding of gas phase • chemistry and plasma-surface interactions. • Plasma diagnostic and surface interaction • measurements are used to understand plasmas • and provide modeling data. • CF4 is a common processing plasma and the radical • recombination chemistry is not well understood.
Experimental Apparatus – top view Optical Emission Langmuir Probe pressure gauge Neutral Analysis Quadrupole Mass Spectrometer Ion Analysis Quadrupole Mass Spectrometer beam Plasma Chamber background chopper Thermocouple * industrial processing plasma use optical emission * very few systems have attempted to make all measurements simultaneously Quartz Crystal Microbalance
Experimental Procedure * mass spectrometer measurements are at wall * Langmuir probe can measure profile
Quartz Crystal Microbalance (QCM) films deposited on microbalance crystal crystal oscillates at characteristic frequency proportional to its mass change in mass causes frequency change Quartz Crystal Microbalance oscillator plasma crystal film
CF3 Recombination Coefficient Fin(CF4) • Assume CF4 formation at walls is • due entirely to CF3 recombination • CF4 balance • in – out + recombination = reaction plasma CF3 CF4 + e CF3, CF2, CF3+, … CF4 • Walls – fluorocarbon deposited • on stainless steel (30 +/- 2 oC) • QCM - negligible deposition rate • APMS - radical and neutral densities • Langmuir Probe - electron energy • distribution (fo) Fout(CF4)
Kdiss calculation = 0.038
Studies of plasma-wall interactions (e.g. Si/O/Cl for gate/trench etch) Studies of high-K etching (e.g. etch precursors, by-products, selectivity) Studies of plasma surface interaction (e.g. N2 plasma / PET; NF3 plasma / elastomer) Result 2002-2003 Milestones