Date of Award
Doctor of Philosophy
R. A. Buchanan, T. T. Meek, M. Breinig
Different surface pretreatments of the substrates and their effect on the nucleation and early growth stages of CVD diamond were studied, and the results were used to design a procedure for growing near-net shape diamond micro machine components. The Mechanisms responsible for nucleation of diamond on various substrate material are still under study and have not been completely explained yet. Studies of different pretreatments that enhance or degrade the nucleation are important for the determination of controlling mechanisms and might lead to better applications of the CVD diamond industry.The mechanical pretreatment consisted of ultrasonic abrasion of the silicon substrate with diamond, SiC, A1203, and TiB2 powders mixed with ethanol. Scanning Electron microscopy (SEM), profilometry, and AFM were used to characterize the surfaces before and after the CVD of diamond. Measurements of the surface roughness showed no significant difference between the roughness of the various abraded samples.Nucleation density was 4 to 8 orders of magnitude higher on the samples abraded with diamond-ethanol slurry than any other material. Increasing the abrasion time appears to have slight effect on the nucleation density. Gross deformation did not seem to affect the nucleation rate either.The effect of ion implantation on the pretreated samples was investigated.Scanning electron microscopy and RBS/Channeling were used to analyze the results of this work. At an energy of 150 KeV, a dose of 2x1015 Si/cm2 was the border line for suppression of nucleation and also for amorphization of both diamond and silicon.Annealing of the substrates at various stages of the CVD process was also studied.SEM, RBS/channeling, and SEM channeling were used for the analysis in this study.Annealing the substrates did not seem to have a significant effect on the nucleation and growth of CVD diamond.The results of the studies on pretreatment were used to design a process for fabrication of diamond microcomponents. The process included ion implantation, CVD growth, and etching. Analysis on these samples was done using all the above mentioned techniques. Controlling the nucleation in the implanted regions is the major key to the control of the minimum resolution of features on the diamond near-net shape micro components.
Ackleh, Samer Sima'an, "Control of CVD diamond nucleation and effects on microcomponent processing. " PhD diss., University of Tennessee, 1999.