Etching through silicon vias having different sizes with minimum depth loading

Abstract

A method for etching a substrate includes providing a substrate including a silicon layer, a dielectric layer, and a mask layer defining a first set of through silicon vias (TSVs) and a second set of TSVs with a first critical dimension (CD) and a second CD, respectively. The first CD and the second CD are different. The method includes depositing a silicon oxide layer using a nonconformal deposition process to provide reverse loading in one of the first set of TSVs and the second set of TSVs corresponding to a larger one of the first CD and the second CD; and performing a rapid alternating process including a plurality of cycles. Each of the plurality of cycles includes a deposition step, a clear step, and an etch step.

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