Patent ID: 9142445
Filing Date: 2015-09-22
Classification: H01L

Abstract:
1. A method comprising: forming an opening in a substrate, wherein the opening in the substrate has (i) sidewalls and (ii) a bottom surface, and wherein the opening in the substrate has a first depth; forming a first masking layer on (i) the sidewalls of the opening and (ii) the bottom surface of the opening; during a first etching operation, selectively etching (i) the first masking layer formed on the bottom surface of the opening such that the first masking layer formed on the sidewalls of the opening is not etched, and (ii) a first portion of the substrate at the bottom surface of the opening such that the opening in the substrate has a second depth, wherein the second depth is different from the first depth, and wherein subsequent to selectively etching the first masking layer, a first portion of the first masking layer remains on the sidewalls of the opening, wherein the first etching operation to selectively etch the first masking layer formed on the bottom surface of the opening is continued, without stopping, until completion of the selective etching of the first portion of the substrate at the bottom surface of the opening; subsequent to selectively etching the first masking layer, forming a second masking layer on (i) the first portion of the first masking layer remaining on the sidewalls of the opening and (ii) the bottom surface of the opening; during a second etching operation, selectively etching (i) the second masking layer formed on the bottom surface of the opening such that the second masking layer formed on the first portion of the first masking layer is not etched, and (ii) a second portion of the substrate at the bottom surface of the opening such that the opening in the substrate has a third depth, wherein the third depth is different from the second depth, and wherein subsequent to selectively etching the second masking layer, a first portion of the second masking layer remains on the first portion of the first masking layer; and subsequent to selectively etching the second masking layer, removing (i) the first portion of the first masking layer remaining on the sidewalls of the opening and (ii) the first portion of the second masking layer remaining on the first portion of the first masking layer.