Masking layer having narrow isolated spacings and the method for forming said masking layer and the method for forming narrow isolated trenches defined by said masking layer

摘要

A process for forming within a masking layer self-aligned narrow isolated spacings having a width that is substantially narrower than the space width that can be created directly using the maximum resolution of available photolithography and the process for utilizing said masking layer to form narrow isolated trenches in a semiconductor substrate. The process involves the following steps: creation of a mask island using conventional photomasking and etching techniques, opposing sides of said island defining the inner walls of the narrow isolated spacings; blanket deposition of a spacer layer, the thickness of which is equal to the desired width of the narrow isolated spacings; blanket deposition of a thick protective layer that is independently etchable over the spacer layer; planarization of the protective layer to or below the top of the spacer layer; masking at least a width equal to the thickness of the spacer layer at two opposing ends of the mask island; and isotropically etching the unmasked spacer layer to form the narrow isolated spacings. Said process thereby creating the masking layer having self-aligned narrow isolated spacings exposing the substrate. At this point the mask protecting the opposing end of the mask island may be removed and the exposed substrate may be etched to form narrow isolated trenches.