Abstract: A two mask process for forming dielectrically filled planarized trenches of arbitrary width in a semiconductor substrate, the masks being of such character that they are amenable to computerized generation. The first mask defines the active regions and subdivides the trench isolation regions into a succession of trench and plateau regions, where the widths of the trench and plateau regions fall within in a dimensional range constrained by photolithographic precision of the masks and the ability to conformally deposit dielectric material into the trenches. With the first etch mask in place, the semiconductor is anisotropically etched to formed the first trench regions. A conformal deposition of dielectric follows, and by virtue of the dimensional constraints ensures substantially void free trench dielectric and a concluding substantially planar topology of the dielectric on the substrate surface.