| 摘要 |
A method for the selective removal of a high-k layer such as HfO2 over silicon or silicon dioxide is provided. More specifically, a method for etching high-k selectively over silicon and silicon dioxide and a plasma composition for performing the selective etch process is provided. Using a BCl3 plasma with well defined concentrations of nitrogen makes it possible to etch high-k with at a reasonable etch rate while silicon and silicon dioxide have an etch rate of almost zero. The BCl3 comprising plasmas have preferred additions of 10 up to 13% nitrogen. Adding a well defined concentration of nitrogen to the BCl3/N2 plasma gives the unexpected deposition of a Boron-Nitrogen (BxNy) comprising film onto the silicon and silicon dioxide which is not deposited onto the high-k material. Due to the deposition of the Boron-Nitrogen (BxNy) comprising film, the etch rate of silicon and silicon dioxide is dropped down to zero. The Boron-Nitrogen (BxNy) comprising film can be removed during the etching process using the right substrate bias (leading to ion bombardment) or after the etching process by a simple water rinse since the Boron-Nitrogen (BxNy) comprising film is water soluble.
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