Microwave plasma modelling in clamshell chemical vapour deposition diamond reactors

Abstract

A microwave plasma model of a chemical vapour deposition (CVD) reactor is presented for understanding spatial heteroepitaxial growth of polycrystalline diamond on Si. This work is based on the TM 0(n>1)p clamshell style reactor (Seki Diamond/ASTEX SDS 6K, Carat CTS6U, ARDIS-100 style) whereby a simplified H 2 plasma model is used to show the radial variation in growth rate over small samples with different sample holders. The model uses several steps: an electromagnetic (EM) eigenfrequency solution, a frequency-transient EM/plasma fluid solution and transient a heat transfer solution at low and high microwave power density. Experimental growths provide model validation with characterisation using Raman spectroscopy and scanning electron microscopy. This work demonstrates that shallow holders result in non-uniform diamond films, with a radial variation akin to the electron density and temperature distribution at the wafer surface. For the same process conditions, greater homogeneity is observed for taller holders, however, if the height is too extreme, the diamond quality reduces. From a modelling perspective, EM solutions are limited but useful for examining electric field focusing at the sample edges, resulting in accelerated diamond growth. For better accuracy, plasma fluid and heat transfer solutions are imperative for modelling spatial growth variation.

Superconducting boron doped nanocrystalline diamond microwave coplanar resonator

“…The SEM images show that in the gap regions, the B-NCD has been successfully etched which was also corroborated using a probe station measurement. Raman spectra is given in Figure 4, showing the first and second order bands of Si at ∼520 cm −1 and ∼965 cm −1 , respectively [31,32,33] and numerous signatures typically associated with BDD at high dopant concentrations. The B-NCD bands are labelled at ∼450 cm −1 (dA), ∼1200 cm −1 (dC), ∼1295 cm −1 (dB), 1332 cm −1 (d) and the wide region at ∼1500-1680 cm −1 (G) [34].…”