Controlled formation of atomic step morphology on micropatterned Si (100)

Abstract

Micro scale features are fabricated on Si (100) surfaces using lithographic techniques and then thermally processed in an ultra high vacuum (UHV) environment. Samples are flash heated at 1200 °C and further annealed at 1050 °C for 18 hours. The surface morphology was examined using an atomic force microscopy (AFM). The process resulted in the formation of symmetric, reproducible step-terrace patterns with very wide atomically flat regions exhibiting highly reproducible step-terrace morphology. 25 µm lithographically patterned cells spontaneously transform into a symmetric formation marked by step bunches pinned by pyramidal structures separated by wide atomic terraces. The pyramidal features are visible using a conventional optical microscope and are to be used as fiducial marks to locate nanoscale features fabricated on the atomically flat terraces.

Atomically Traceable Nanostructure Fabrication

“…32 While it has been shown previously that high temperature sample processing will induce significant atomic scale surface reconstruction, the grid pitch used here is great enough to have little effect on the surface reconstruction in the middle of the squared defined by the grid. 34 However, near the edges of the patterned areas, step bunching does occur with asymmetry that depends upon the direction of current flow during sample preparation. 34 Since the optical imaging is performed at an oblique angle relative to the surface, small changes in height on one side of a trench relative to the other will induce additional uncertainty in pattern location-especially when compared to plan-view imaging as in AFM or normal SEM.…”

“…34 However, near the edges of the patterned areas, step bunching does occur with asymmetry that depends upon the direction of current flow during sample preparation. 34 Since the optical imaging is performed at an oblique angle relative to the surface, small changes in height on one side of a trench relative to the other will induce additional uncertainty in pattern location-especially when compared to plan-view imaging as in AFM or normal SEM. After the tip engages the sample, the 10 μm focal spot size of the microscope coupled with the ~20 μm post-processing fiducial linewidth results in an approximate uncertainty in pattern position identification of ±27 μm.…”

Silicon epitaxy on H-terminated Si (100) surfaces at 250 °C

“…Samples of 4 mm × 10 mm size were diced from the wafer. The samples were cleaned using a standard piranha and RCA recipe, followed by a dip in 2 % hydrofluoric acid [27],[28] . Afterwards, the samples were mounted on a standard Omicron sample holder * and loaded into a UHV preparation chamber with an in situ UHV heater (base pressure 5 × 10 −8 Pa).…”

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].…”