| 摘要 |
A process for etching a dielectric layer with an underlying stop layer, particularly in a counterbore process for a dual-damascene interconnect structure. The substrate is formed with a lower stop layer, a lower dielectric layer, an upper stop layer, and an upper dielectric layer. The initial deep via etch includes at least two substeps. A first substep includes a non-selective etch through the upper stop layer followed by a second substep of selectively etching through the lower dielectric layer and stopping on the lower stop layer. The first substep may be preceded by yet another substep including a selective etch part ways through the upper dielectric layer. For the oxide/nitride compositions, the selective etch is based on a fluorocarbon and argon chemistry, preferably with a lean etchant combined with a richer polymer former, and the non-selective etch includes a fluorocarbon or hydrofluorocarbon, argon and an oxygen-containing gas, such as CO.
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