Method for forming a void free isolation structure utilizing etch and refill techniques

摘要

A void-free isolated semiconductor substrate is described which contains a pattern of substantially vertically sided trenches within a semiconductor body. The pattern of isolation trenches isolate regions of monocrystalline semiconductor material which may contain active and passive semiconductor devices. A first insulating layer is located upon the sidewalls of the trenches. The base or bottom of the trenches is open to the monocrystalline semiconductor body. An epitaxial layer extending from the base of the trenches fills the pattern of trenches up to a level from the upper surface of the trenches as specified approximately by the equation: y=0.34x where y is the distance between the epitaxial layer and the top surface and x is the trench width. The preferred range for the trench width x is about 10 micrometers or less. A polycrystalline silicon layer fills the additional portion of the pattern of trenches above the upper surfaces of the epitaxial layer. A second insulating layer is located on the polycrystalline silicon layer within the trenches for isolation of the pattern of trenches from the ambient. It is the dense epitaxial monocrystalline semiconductor which prevents the formation of voids within the pattern of trenches. The polycrystalline silicon layer above the epitaxial layer completely covers the undesirable sharp faceted structure at the top of the epitaxial semiconductor growth structure.