Kinetics of etching of silicon dioxide in a CF4 plasma

Etching of silicon dioxide in CF4 plasmas was theoretically investigated, a nd thereon a mathematical model to describe the etching process was formula ted. By using a Langmuir-type surface chemistry model shown in the literatu re and the plasma chemistry model from our previous work, the etch rate was derived as a function of the discharge power. The data of the etch rate of silicon dioxide in CF4 plasmas in the literature were analyzed based on th is etch model. As a result of this analysis, a linear relationship between the reverse etch rate and the reverse discharge power was found, which veri fies the model and leads to another finding that the ion energy flux to the etch surface is proportional to the discharge Fewer. The intercept and gra dient of the linear relation give estimates for the gradient of etch rate a t zero discharge power and the etch rate at the infinite discharge power, r espectively. These estimated values are found to depend on the flow rate. B ased on this analysis, a mathematical form of the etch rate as a function o f the flow rate of the feedstock gas was obtained and shown to be fairly cl ose to the experimental results in the literature. (C) 2000 The Electrochem ical Society. S0013-4651(99)08-048-9. All rights reserved.