Optical Emission Spectroscopy from rf Sputtering Plasma of Gd-Co Alloy

A study was performed on the rf sputtering plasma of pure cobalt and gadolinium metals and of Gd
₂₆
Co
₇₄
alloy using optical emission spectroscopy (OES), for various discharge conditions such as the argon pressure P
_Ar
, target voltage V
_rf
, and substrate bias voltage V
_b
. From measurements of OES line intensities and deposition rates for various values of P
_Ar
, V
_rf
and the focussing field H, it was found that the line intensities of both Co and Gd atoms are represented as linear or square functions of the atomic densities in the plasma. Moreover, the preferential resputtering effect of Gd atoms was also confirmed from the change in line intensity for a negative bias voltage with V
_b
≧20 V.