Interface stability in stressed solid-phase epitaxial growth

Abstract

The role of applied stress on interface stability during Si solid-phase epitaxial growth was investigated. Transmission electron microscopy observations of growth interface evolution revealed in-plane uniaxial compression ͑tension͒ led to interface instability ͑stability͒. Additionally, level set simulations revealed that the stress-influenced interface instability was accurately modeled by adjusting the strength of the linear dependence of local interface velocity ͑rate of change of interface position with respect to time͒ on local interface curvature proposed in previous work. This behavior is explained in terms of tension in the growth interface controlling interface stability during growth; it is argued that compressive ͑tensile͒ stress tends to reduce ͑enhance͒ interfacial tension and results in interfacial instability ͑stability͒ during growth.

Solid-Phase Epitaxy

“…Morarka et al [101] have argued that the magnitude of the stress concentration is insufficient to account quantitatively for the observations, and have advanced a model in which the applied stress is hypothesized to modify the interfacial tension. They have been able to obtain good agreement with morphologies they observe in multidirectional SPE in device fabrication geometries.…”

Defective Solid-Phase Epitaxial Growth of Si

“…In principle, for an interface with peaks and trough, variation in the localized stress state should exist due to differences in the elastic properties of amorphous and crystalline Si (Witvrouw and Spaepen, 1993). However, later work showed that variations in the localized stress state, even in the presence of substantial perturbations, were negligible (Morarka et al, 2011). It was thus advanced that a synergistic effect between the applied stress and the localized growth interface curvature was responsible for controlling morphology, though the origin of this is not yet understood.…”

“…If this system is now annealed to effect SPEG, the growth interface will exhibit morphological instability as well as the generation of defects depending on the sign of the applied stress. Specifically, if σ 11 ¼ 0 (stress free) or σ 11 > 0 (tensile), the growth interface will remain flat during SPEG and no defects will be generated, while if σ 11 < 0 (compressive), the growth interface will roughen during SPEG and defects will be generated at the growth interface (Barvosa-Carter et al, 1998, 2004Morarka et al, 2011;Phan et al, 2001;Rudawski et al, 2007Rudawski et al, , 2008bSage et al, 2000;Sklenard et al, 2013). Fig.…”

“…Extensive prior work established that the velocity of the growth interface is highly sensitive to the annealing temperature (Olson and Roth, 1988;Roth et al, 1990) used to effect SPEG, the crystallographic orientation of the substrate, the presence of impurities Kennedy et al, 1977;Lietoila et al, 1982;Morarka et al, 2010;Suni et al, 1982;Williams and Elliman, 1983;Williams and Short, 1983) within the α-Si layer, and the application of external stress (Aziz et al, 1991;Barvosa-Carter and Aziz, 2001;BarvosaCarter et al, 1998BarvosaCarter et al, , 2004Chaki, 1991Chaki, , 1994Lu et al, 1989;Morarka et al, 2011;Nygren et al, 1985;Phan et al, 2001;Rudawski and Jones, 2009;Rudawski et al, 2007Rudawski et al, , 2008bRudawski et al, ,c,d, 2009aSage et al, 2000;Sklenard et al, 2013). The exact details of the effect each of these considerations has on the macroscopic nature of the SPEG process will not be described in detail here.…”

“…Interestingly, it is also possible to apply an external uniform stress and influence the formation of defects during SPEG ( Barvosa-Carter et al, 2004;Morarka et al, 2011;Phan et al, 2001;Rudawski et al, 2007Rudawski et al, , 2008bRudawski et al, ,c,d, 2009aSage et al, 2000;Sklenard et al, 2013). Consider a (001) Si wafer with a continuous α-Si layer extending to the wafer surface with a uniform in-plane uniaxial stress applied along [110] (σ 11 ).…”