Effect of Non-Hydrostatic Stress on Kinetics and Interfacial Roughness During Solid Phase Epitaxial Growth in Si

Abstract

We report preliminary in-situ time-resolved measurements of the effect of uniaxial stress on solid phase epitaxial growth in pure Si (001) for the case of stress applied parallel to the amorphous-crystal interface. The growth rate is reduced by the application of uniaxial compression, in agreement with previous results. Additionally, the velocity continues to decrease with time. This is consistent with interfacial roughening during growth under stress, and is supported by both reflectivity measurements and cross-sectional TEM observations. We present a new kinetically-driven interfacial roughening mechanism which is consistent with our observations.

Kinetically Driven Growth Instability in Stressed Solids

“…The activation strain tensor describes the stress dependence of G ‫ء‬ . Measurements for (001) yield first and second diagonal elements of 10.14 V and a third diagonal element of 20.35 V, where V is the atomic volume of the crystal; off-diagonal elements are zero [4,9,10]. As the interface orientation varies, the atomistic processes occurring at the interface that determine the activation strain tensor are assumed to retain their orientation with respect to the lattice (which would result if, e.g., all action occurred at step edges), resulting in V ‫ء‬ and G ‫ء‬ fixed to the lattice and independent of interface orientation.…”

On Kinetically vs. Energetically Driven Growth Instabilities in Solid and Vapor Phase Epitaxy

“…Just such a dependence of the interfacial mobility on stress has been observed [14,16] in SPEG of Si(001), characterized by * 11 V = +0.14 times the atomic volume Ω of crystalline Si.…”

“…We have previously called attention to the mobilities of the interfaces or atoms involved in growth [13,14] and characterized the stress-dependence of mobilities [14][15][16][17][18], and we and others have predicted how the changes in mobility due to stress also help determine the growth morphology [5-7, 10-12, 16, 19, 20].…”

“…The stress concentration in the trough results in a local interfacial mobility that is smaller than that at the peak; hence the peak grows faster and the perturbation tends to amplify. I call this the Barvosa-Carter ("BC") instability [10,16]. The stress effect on mobility is first order in stress, thus giving rise to opposite amplification behavior under tension and compression.…”

“…In contrast, the elastic strain energy in the energetically-driven Asaro-Tiller ("AT") instability [1] is second order in stress, and therefore is destabilizing under both tension and compression. Hence if the interface is unstable under compression, which is generally observed in many growth situations and specifically known for solid-phase epitaxial growth (SPEG) of Si(001) [10,16] from an amorphous parent phase, and the stress-dependence of the mobility is the predominant factor in determining interface instability, then the interface should be stable in tension. This is indeed what we see in the mja128.pdf laboratory.…”