FIG. 2E is a cross-sectional view of semiconductor device 200 following formation of dielectric and conductive layers in accordance with some embodiments. A first dielectric layer 112 is deposited along the exposed surfaces of substrate 102 and the sidewalls and bottom surface of trenches 110 and 110′. In some embodiments where trench mask pattern 108 remains, trench mask pattern 108 is between a top surface of substrate 102 and first dielectric layer 112.

In some embodiments, the first dielectric layer 112 is formed by using chemical vapor deposition (CVD), atomic layer deposition (ALD), high density plasma CVD, sputtering, atomic layer deposition (ALD), or any other suitable method, or combination of methods, for forming a generally conformal dielectric layer on the exposed surfaces of both the substrate 102 and the trenches 110, 110′. In some embodiments, the first dielectric layer 112 includes a single layer. In some embodiments, the first dielectric layer 112 includes a multilayer structure of one or more suitable dielectric materials. Examples of suitable materials for the first dielectric layer 112 include, but are not limited to, silicon oxide (e.g., SiO₂), silicon nitride (e.g., Si₃N₄), SiON, SiC, SiOC, or a combination thereof.