Method of Evenly Filling Isolation Trenches
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-04
Onto a substrate, provided with trenches, a polyimide layer and a photoresist layer with a planar surface are deposited and etched at a photoresist/polyimide etch rate ratio of about 0.7 until the substrate surface is exposed and small elevations, that disappear upon baking, are left above the filled trenches. The described method is self-aligned. The first method steps are explained with reference to the cross-sectional view of Fig. 1. Onto substrate 1, provided with trenches 2, a polyimide coating 3 is spun and baked at about 125ŒC. Then, a photoresist layer 4 is spun onto polyimide coating 3, baked at about 95ŒC, and blanket-exposed at 300 to 400 mjoules. The structure (Fig. 1) thus obtained has a planar surface.