CHARACTERIZATION OF AR CU ELECTRON-CYCLOTRON-RESONANCE PLASMAS USING OPTICAL-EMISSION SPECTROSCOPY/

Optical emission spectroscopy is used to investigate trends with chang es in processing parameters for Ar/Cu plasmas in an electron-cyclotron -resonance (ECR) plasma deposition system. The primary motivation for this work is to monitor trends in ionization fractions for copper depo sition plasmas using a noninterfering diagnostic tool. The system, whi ch consists of a solid copper sputter target coupled to a permanent ma gnet ECR microwave plasma system, is operated in the range of 1-6 mTor r argon with net microwave input power of 500-1500 W. Emission from th e following excited states is monitored: Ar neutrals (696.5 nm); Ar io ns (488 nm); Cu neutrals (521.8 and 216.5 nm); and Cu ions (213.6 nm). Cu ion emission and Cu neutral emission monotonically increase with n et microwave input power but at slightly different rates for different pressures, while argon-ion emission as a function of pressure shows a broad peak around 4 mTorr. The ratio of Cu ion emission to Cu neutral emission is used as an indicator of the relative ionization efficienc y for Cu and peaks neat 5 mTorr. Spectroscopic estimates of electron t emperature differences between pure Ar and Ar/Cu plasmas are also pres ented.