| 摘要 |
A method for forming features in an etch layer in an etch stack with an etch mask over the etch layer, wherein the etch mask has etch mask features with sidewalls, where the etch mask features have a first critical dimension, is provided. A cyclical critical dimension reduction is performed to form deposition layer features with a second critical dimension, which is less than the first critical dimension. Each cycle, comprises a depositing phase for depositing a deposition layer over the exposed surfaces, including the vertical sidewalls, of the etch mask features and an etching phase for etching back the deposition layer leaving a selective deposition on the vertical sidewalls. Features are etched into the etch layer, wherein the etch layer features have a third critical dimension, which is less than the first critical dimension.
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