Method of forming a layer on a semiconductor substrate having a plurality of trenches

摘要

A method of fabricating a semiconductor device is illustrated. A substrate having a plurality of trenches is provided. The plurality of trenches include trenches having differing widths. A first layer is formed on the substrate including in the plurality of trenches. Forming the first layer creates an indentation in the first layer in a region overlying a trench (e.g., wide trench). A second layer is formed in the indentation. The first layer is etched while the second layer remains in the indentation. The second layer may protect the region of indentation from further reduction in thickness. In an embodiment, the first layer is polysilicon and the second layer is BARC of photoresist.