Arrays of widely spaced atomic steps on Si(111) mesas due to sublimation

Abstract

Steps with spacings of microns form on top of mesas fabricated on Si(111) that is annealed at temperatures where sublimation becomes important. Upon annealing, mesas first develop ridges along their edges, effectively creating craters which then become step-free by a step flow process described in the literature. Due to the miscut of the average surface from (111), ridge breakdown occurs on one edge of each mesa as sublimation proceeds. The breakdown point then acts as a source of steps which spread out over the mesa surface. The distribution of steps in the resulting step train depends on the sublimation rate, direct step-step interaction and the diffusive exchange of atoms among the steps. Computer simulations using BCF (Burton, Cabrera and Frank) theory provide insight into the controlling processes. The results suggest that self-organization of the wide terrace distributions in the low step density area occurs under sublimation. We compare the experimental and predicted step distributions.Comment: 11 pages, 3 figures with 7 subfigures revised for submission to Surface Scienc

Early morphological changes on Si(111) surfaces during UHV processing

“…However, this theory should only be valid for isotropic solids ͑e.g., glasses͒ but may also be applicable to crystals above their roughening or premelting transitions. However, as reported earlier, 59 the presence of the ridge does allow the formation of regions with single atomic steps separated by wide atomically flat terraces ͑Fig. This is indeed consistent with what we observe experimentally as long as the surface is relatively rough.…”

Surface gate and contact alignment for buried, atomically precise scanning tunneling microscopy–patterned devices

“…12 It is believed that high temperature annealing causes the movement of atomic steps across terraces by a step-flow evaporation process. The exact nature of the kinetic processes that cause the surface morphology of Si substrates to change and lead to the formation of large step-free areas on Si͑100͒ and Si͑111͒ during high temperature annealing is still a matter of debate.…”

“…[9][10][11][12] Patterning square ridge structures by optical lithography, Lee and Blakely 10 were able to produce arrays of step-free regions up to 20 ϫ 20 m 2 in size on the Si͑100͒ surface after an anneal at 1000-1150°C in UHV. Firstly, the process is fully electron beam lithography ͑EBL͒-based allowing smaller ͑Ͻ500 nm features size͒ and shallower ͑ϳ60 nm͒ markers that can be imaged by the STM directly, thereby increasing the overall alignment accuracies down to ϳ100 nm.…”

Эволюция микролунок на широких террасах поверхности Si(111) в процессе высокотемпературного отжига

“…В случае высокотемпературного термического отжига или эпитаксиального роста информацию об атомных процессах можно извлечь из анализа кинетики трансформации литографически структурированных поверхностей [6,7]. Однако теоретическое описание экспериментальных исследований процессов трансформации литографических структур, созданных на вицинальной поверхности кристалла, затрудненo из-за необходимости учeта их взаимодействия с вицинальными ступенями, дислокациями и другими дефектами поверхности [8,9].…”