Stability and precipitation kinetics in Si(sub 1(minus)y)C(sub y) /Si and Si(sub 1(minus)x(minus)y)Ge(sub x)C(sub y)/Si heterostructures prepared by solid phase epitaxy

摘要

This study investigates the stability of metastable Si(sub 1(minus)y)C(sub y)/Si heterostructures during rapid thermal annealing (RTA) over a temperature range of 1,000--1,150 C. Heterostructures of Si(sub 1(minus)y)C(sub y)/Si and Si(sub 1(minus)x(minus)y)Ge(sub x)C(sub y)/Si (x (equals) 0.77, Y (<=) .0014) were formed by solid phase epitaxy from C implanted, preamorphized substrates using a 30 minute 700 C anneal in N(sub 2). The occupancy of C in substitution lattice sites was monitored by Fourier Transform Infrared Absorption spectroscopy. The layer strain was monitored by rocking curve X-ray diffraction and the structural changes in the layers were determined using plan-view and X-sectional transmission electron microscopy (TEM). For anneals of 1,150 C or above, all the substitutional C was lost from the Si lattice after 30 seconds. TEM verified that the strain relaxation was the result of C precipitating into highly aligned (beta)SiC particles rather than by the formation of extended defects. No nucleation barrier was observed for the loss of substitutional C. Preliminary results will also be discussed for Si(sub 1(minus)x(minus)y)Ge(sub x)C(sub y)/Si heterostructures where there is the additional factor of the competition between strain energy and the chemical driving forces.