PROCESS CONTROL METHOD FOR THIN FILM PLASMADEPOSITION

摘要

During the reactive magnetron sputter deposition of the layers of optical material in a highrnvacuum environment, a phenomenon occurs, after target source replacement, when optical indexrnvalues of the plasma deposited materials are greater than required. With the intention ofrncontrolling the resultant index to median specification value throughout the entire target life,rnexperiments were conducted to determine the optimum parameter values of ion gun oxygen flowrnrate, magnetron argon flow rate, and magnetron power. A satisfactory operating range wasrndetermined for each parameter based on previous studies. These values formed a basis for arndesign of experiment three-level full factorial study with magnetron power (+/- 17%), oxygenrnflow (+/- 20%), and argon flow (+/- 20%). The results indicate that when a new target isrninstalled, the parameters need to be changed concomitantly. A follow-up study indicated thatrnparameters of low argon flow, low kilowatt power, and a high oxygen flow produced indexrnlayers that meet requirement. When the target approaches its midlife of usage, an adjustment tornthe nominal conditions indicated above will return the index to satisfactory results.