| 摘要 |
A process is described for planarizing an isolation structure in a substrate. The process includes depositing a pad protective material over an upper surface of the substrate, and selectively removing portions of the pad protective material to expose portions of the substrate and to form sidewalls in the pad protective material. A trench is formed in the exposed portions of the substrate, and a trench fill material is deposited in the trench and over the pad protective material. A trench protective material is deposited over the trench fill material and in contact with the sidewalls of the pad protective material, such that the pad protective material and portions of the trench protective material together form a continuous protective material layer. Portions of the trench protective material and the trench fill material are selectively removed down to the level of the upper surface of the pad protective material. Finally, the pad protective material and any remaining trench protective material is removed, leaving the trench filled with trench fill material that is planarized at the upper surface of the substrate. By forming a continuous protective material layer that completely covers the trench fill material in the trench, that material is protected during later process steps that nonselectively remove trench fill material lying outside the trench. In this manner, the trench fill material lying outside the trench may be removed without photolithographic masking and patterning steps. Thus, the process according to the invention reduces the cost and complexity of planarizing the trench fill material.
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