Method for forming ultra fine deep dielectric isolation

DETAILED DESCRIPTION In accordance with the present invention, a method is described for the formation of ultra fine grooves that can be filled with dielectric material which can then act as dielectric isolation for highly dense integrated circuit devices.
This method is accomplished by first forming a first layer of material on the silicon body wherein the dielectric isolation is desired.
The layer material is formed over a first set of alternately designated device regions with bare silicon therebetween.
A conformal coating is deposited over the first layer and on the silicon body included in a second set of alternately designated device regions and the designated isolation regions.
The thickness of the coating is made to be substantially the width of the planned dielectric isolation.
A second layer is then deposited over the conformal coating.
The first layer and the conformal coating are composed of different materials.
The topmost surface of the second layer and the conformal coating are planarized by removing partially the second layer and conformal coating from the first layer wherein the second set of alternately designated device regions in the silicon body are covered by the conformal coating and the second layer with portions of the conformal coating separating the covers for the first and second sets of device regions.
The vertical portions of the conformal coating separating the covers are then removed down to the silicon body in the designated isolation regions.
These covers are then used as an etch mask for a etching of grooves in the silicon body to the desired depth of the dielectric isolation.
The grooves are then filled with dielectric material to form the dielectric isolation.
The preferred method of filling the grooves is by a thermal oxidation process.