REMOTE PLASMA-ENHANCED CHEMICAL VAPOR DEPOSITION (RPCVD) PROCESS FOR LOW TEMPERATURE (≤450^°C) EPITAXY OF Si AND Si_1−x, Ge_x

ABSTRACT

Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD) is a low temperature growth technique which has: been successfully employed tor in situ remote hydrogen plasma cleaning, dielectric deposition, silicon homoepitaxy and Si_1−x, Ge_x heteroepitaxy in the temperature range of 150^°C-450^°C. The growth rate of epitaxial Si in the RPCVD process can be varied from 0.4Å/min to 50Å/min by controlling the r-f power. The wide range of controllable growth rates makes RPCVD a excellent tool for applications ranging from quantum-well type structures to more conventional Si epitaxy. Epitaxial Si and Si_1−x, Ge_x films with defect densities below the detectable limits of TEM (∼10⁵ cm^{− 2} or less) and low oxygen content (∼3×10^1B cm^{− 3}) have been achieved by RPCVD. The in situ boron-doped Si films have been grown on n-typo, phosphorus-doped substrates to form p-n junctions for mesa diode fabrication. The mesa diodes with different boron doping concentrations (10¹⁷-10¹⁹ cm^{− 3}) show good current-voltage characteristics with ideality factors of 1.2-1.3. A Si/Si_0.BGe_0.2 superlattice structure with sharp Ge transitions has been achieved due to the low temperature capability of the RPCVD process. The fundamental growth kinetics of the RPCVD process have been studied by measuring plasma density, plasma potential and electron temperature as a function of process parameters using a Langmuir probe and by measuring growth rate as a function of process parameters such as r-f power, temperature and precursor partial pressure.