Papers by Author: Brian H. Ponczak

Abstract: A method to improve the uniformity of epitaxial wafers grown in planetary rotation reactors through analysis of intentionally stalled wafer measurements is described. A set of basis functions that are completely uniform when rotated in the reactor environment are described and used to construct a nearest uniformity producing profile (NUPP). The methodology for use of stalled wafer profiles and comparison to the NUUP allows easy identification of the changes in process parameters necessary for more uniform epitaxial growth. Although described here as applied to SiC epitaxial growth, this method is applicable to all planetary rotation reactors which are utilized for SiC and III-V semiconductor epitaxial growth.

Abstract: A quadrupole mass spectrometer unit was utilized to accurately detect the chemical species present inside a SiC CVD reactor growth chamber before, during, and after epitaxial deposition. The in-situ mass spectrometer has been able to confirm the presence of silane (SiH4) and propane (C3H8) decomposition products (eg. Si and CH4) that were predicted from chemical modelling, and give insight into specific reaction kinetics. Additionally, the mass spectrometer has positively detected trace amounts of oxygen, which has helped to identify process weaknesses and possible sources of vacuum leaks.

Abstract: A series of designed experiments have been conducted over a period of years in a multiwafer, planetary rotation, epitaxial reactor to quantify the effects of various epitaxial growth process parameters on the resulting SiC epitaxial layers. This paper summarizes the results obtained through statistically designed experiments varying process parameters and their resultant effect on the layer thickness, carrier concentration and the variability of these parameters wafer-to-wafer, and within a wafer.