| 摘要 |
A method for physical etching using a multilevel hard mask. A substrate having a multilayer structure thereon is provided. A BPSG layer, a masking material layer and a patterned photoresist layer are sequentially formed on the multilayer structure, wherein the masking material layer has a high selective etching ratio for the BPSG layer. A pattern of the patterned photoresist layer is transferred to the masking material layer, and then transferred to the BPSG layer. The masking material layer and the BPSG layer, which function as a multilevel hard mask, are used to physically etch the multilayer structure to form a trench therein.
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