METHODS AND STRUCTURES TO PREVENT SIDEWALL DEFECTS DURING SELECTIVE EPITAXY

摘要

Trenches (and processes for forming trenches to reduce or prevent crystal defects in selective epitaxial growth of group III-V type or germanium (Ge) material (eg, “buffer” material) from the top surface of the substrate material) ) Is provided. Defects may arise due to selective epitaxial sidewall growth and collisions between oxide trench sidewalls. These trenches include (1) a trench having sidewalls inclined at an angle of 40 to 70 degrees (eg, 55 degrees, etc.) relative to the substrate surface; And/or (2) a coupling trench having an upper trench above and surrounding the opening of the lower trench (eg, the lower trench may have sloped sidewalls, short vertical walls, or long vertical walls) do. These trenches reduce or prevent defects in epitaxial sidewall growth when the growth abuts or grows against the vertical sidewalls of the trench in which the sidewall is grown.