Role of Glycine in Chemical Mechanical Planarization (CMP) of Copper SFR Workshop May 24, 2001 Serdar Aksu, Fiona M. Doyle Berkeley, CA 2001 GOAL: to delineate specific roles of a range of complexing agents and oxidizers in copper CMP by 12/30/2001. 5/24/2001

Objective and Methods In copper CMP, electrochemical and mechanical mechanisms are not well understood. Develop a foundation for understanding the behavior of slurries with complexing agents using glycine as a model reagent Comparison of Cu electrochemical behavior in aqueous solutions with and without glycine in terms of Potential-pH diagrams Polarization experiments Comparison of in-situ Cu electrochemical behavior during polishing by slurries/solutions with or without glycine In-situ polarization experiments In-situ monitoring of open circuit potential (EOC) 5/24/2001

TYPICAL METAL (Cu, W, Al etc.) CMP SLURRY CHEMICALS Planarization Mechanism in Metal CMP by Kaufman’s Tungsten CMP Model 1- Removal of Passivating Film by Mechanical Action at Protruding Areas 2- Wet Etch of Unprotected Metal by Chemical Action. Passivating Film Reforms 3- Planarization by Repetitive Cycles of (1) and (2) Metal Passivating Film TYPICAL METAL (Cu, W, Al etc.) CMP SLURRY CHEMICALS INHIBITORS: Benzotriazole (BTA) OXIDIZERS: H2O2, KIO3, Fe(NO3)3 COMPLEXING AGENTS: NH3, EDTA, Glycine, Ethylene Diamine PASSIVATION DISSOLUTION 5/24/2001

Experimental Techniques Rotating Disk Electrode In-situ Electrochemical Experiments Rotator Frame w=200 rpm Rotating Cu Disk electrode Luggin Probe & Reference Electrode Fritted Glass Gas bubbler P=27.6 kPa Magnetic Stirrer Pt Counter Electrodes Copper Working Electrode Solution / Slurry pool (Chemicals / Alumina abrasive Particles w/ Average Size ~ 120 nm from EKC Tech.) Suba 500 Polish Pad (Rodel Corp) 5/24/2001

Copper Electrochemical Behavior No Glycine CuT=10-5 RDE 200 rpm pH=4 pH=9 pH=12 CuT=10-5 ; LT=10-2 10-2 M Glycine 5/24/2001

Polishing w/ pad and 5 % Al2O3 In-situ Polarization Diagrams No Glycine 10-2 M Glycine pH=9 No abrasion Polishing w/ pad only Polishing w/ pad and 5 % Al2O3 No Glycine 10-2 M Glycine pH=12 5/24/2001

In-situ Open Circuit Potential Measurements Without Glycine With 10-2 M Glycine 5/24/2001

Conclusions Polarization results well correlated with potential-pH diagrams No significant changes in in-situ polarization for active behavior Mechanical components significantly affected in-situ polarization for active-passive behavior Kaufman’s tungsten CMP model is also valid for Cu CMP Glycine (complexing agents) may enhance the polishing efficiency 5/24/2001

Future Goals Investigation of Cu electrochemical behavior in ethylenediamine (En) and ethylenediaminetetraacetic acid (EDTA) Studying Cu polishing behavior in EDTA Delineating the synergy effect between chemical (electrochemical) and mechanical contributions Exploration of the role of chemical oxidizers, especially H2O2 5/24/2001