Research On A Pulsed Diode Sputtering Technology For Copper Film Deposition

A pulsed diode sputtering technology for film deposition was proposed andresearched in this thesis when considered the development and achievement in highpower pulsed magnetron sputtering technology in recent years, to avoid the defect oflow target utilization and low structural flexibility in magnetron sputtering.The development process of pulsed glow discharge, as well as the influence to it byparameters of pulsed power, Argon pressure, and target-substrate distance, was studiedby measuring and analyzing the target current curve. Plasma density in different time inthe process of pulsed discharge was acquired by using the Langmuir probe creatively,and the development of plasma density in different pressure and different position wasstudied too. The mechanism of the influences of the parameters to the deposition rateand surface quality of copper films was investigated by analyzing cross-section andsurface morphologies observed by SEM and surface hardness and adhesion obtained bya nano indenter XP system.Research in the target current curve showed that the pulsed glow discharge isconstituted by a starting phase, which is shortened by the increase of target voltage andArgon pressure, and a later stabilizing phase, and when the target voltage and Argonpressure were both in high level, self-sputtering was kindled and there would be a slightcurrent decrease before stabilizing phase. Target current is significantly influenced bytarget voltage and Argon pressure, and the target-substrate distance and geometrystructure have little to do with the current.In the starting phase, Plasma density has an apparent hysteresis when comparedwith the target current, and when glow discharge ceased in one pulse, the plasmadensity will maintain for a while, and for longer when pressure increased, instead ofdecreasing immediately. No apparent hysteresis was observed when compared theplasma density curves obtained in different position.Study in deposition rate and surface morphology revealed that the deposition rate ismainly controlled by the quantity of sputtered atoms, its average initial energy, and theaverage times of collision before they reach the substrate, and the surface quality of filmis greatly influenced by the substrate temperature, the residual energy of deposited atoms, and the deposition rate.The peak current density can reach a level of102mA/cm2, and the plasma density1012cm-3, in the pulsed diode sputtering technology. Films deposited in two differenttarget-substrate structures both showed good thickness uniformity, and in propercondition, both acquired smooth and dense films.