Diagnostic and analytical study on diamond deposition in inductively coupled plasmas

Summary form only given. The majority of research on diamond chemical vapor deposition is conducted at moderate pressures of several tens of torr. In contrast, low pressures on the order of millitorr are highly desirable for controlling elementary processes at the surface due to long mean-free path of ions and radicals. In this study, the neutral radicals such as H and CH₃ and positive ions responsible for diamond growth in a low-pressure inductively coupled plasma were detected by vacuum ultra-violet laser absorption spectroscopy and mass spectrometry as a function of pressure (10-80 mtorr). The growth rate and morphology of diamond were examined by applying a positive substrate and inserting a grid mesh to control the ion-bombardment energy. Theoretical growth rates were obtained from the measured H and CH₃ densities by using contour lines of constant growth rates based on a simple growth model to examine the validity of the measured data. A threshold H density above which the growth is possible was determined to be in the range of 10¹¹-10¹² cm^-3 by a kinetic rate analysis for desorption and incorporation of adsorbed CH ₃ with an aid of H interactions