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Summary form only given, as follows. An experiment was designed using response surface methods to investigate the effects of Cl2/BCl3 gas flows and flow ratios to investigate the plasma etching of 0.35 μm Al-Cu patterns. The objective was to produce a robust process which can be implemented into future production. The equipment used for this experiment was an ECR Metal Etcher. Various experimental runs were performed across a wide range of gas flows and flow ratios. The evaluation criteria included maximizing the selectivity between photoresist and SPSG glass, maximizing the remaining photoresist after the Al-Cu plasma etch, and minimizing etch residues on the oxide surface. In addition, pattern profiles were analyzed for tapering and notching. Following the experiment, the data was analyzed and verified with confirmation testing. Preliminary descriptions of charging effects during the plasma etch are proposed as well as basic insights into the process and similar equipment. Vacuum levels contributed to residue removal. Some unusual effects at higher gas flow rates are also presented. The results of the experiment as well as additional insights into this process are also presented in this paper.