Surface kinetics of polyphenylene oxide etching in a CF4/O-2/Ar downstreammicrowave plasma

A downstream microwave plasma etcher with in situ diagnostics has been cons tructed to elucidate the chemical mechanisms in plasma etching of polypheny lene oxide (PPO). CF4/O-2/Ar reactant gases are used. Stable reaction produ cts are investigated with mass spectrometry while reactive-free radical inf ormation is obtained using optical emission spectroscopy. Additionally, the weight loss of PPO is measured to determine average etch rate. A linens co rrelation between weight loss measurements of PPO laminates and integration of CO and CO2 formation measured by mass spectrometry suggests that real-t ime monitoring of polymer etching can be achieved. Etching dynamics are stu died with gas compositions of CF4 varied from 6.6 to 30%. The etch process exhibits a dynamic reduction in rate with CF4 greater than or equal to 20%. C-1s spectra of X-ray photoelectron spectroscopy show an increase in fluor ination of the etched surface with CF4%. A kinetic model based on the dynam ic change of the number of carbon sites that are fluorinated is proposed. ( C) 2000 The Electrochemical Society. S0013-4651(99)07-106-2. All rights res erved.