Selective area epitaxy is the local growth of epitaxial layer through a patterned dielectric mask (typically SiO2 or Si3O4) deposited on a semiconductor substrate. Semiconductor growth conditions are selected to ensure epitaxial growth on the exposed substrate, but not on the dielectric mask. SAE is formed by opening seed windows on an oxidized Silicon substrate which is typically < 100 > in orientation. The seed window edges are aligned at 45" to the wafer flat, and are along the [loo] direction. Epitaxial growth is initiated selectively in the seed windows on the exposed regions. The growth is referred to as SEG when the Silicon is confined within the oxide walls, and until it reaches the level of the oxide. If the growth is continued, the Silicon grows out of the seed hole and laterally over the masking oxide to produce a single crystal layer of Silicon called Epitaxial Lateral Overgrowth(EL0)
FACTORS EFFECTING SAE
(a) Temperature of growth (b) Choice of mask (c) Orientation of window (d) Mask to window ratio (e) Influence of etchant (f) Quality of mask (g) Influence of shape of window