| 摘要 |
A wet process utilizing a dilute acid oxidant solution, for example, a dilute sulfuric acid with hydrogen peroxide is used in the fabrication of a metal gate electrode of a semiconductor device, offering high etch selectivity and high controllability to achieve a desired profile for the metal gate electrode. In some embodiments, the dilute acid oxidant solution is a dilute sulfuric peroxide solution, comprising at least 50% or 80% by weight of water, less than 30% or 15% by weight of sulfuric acid, and less than 20% or 20% of hydrogen peroxide with optionally less than 100 ppm or 30 ppm ozone. In some embodiments, the dilute sulfuric peroxide solution further comprises less than 100 ppm of hydrofluoric acid. The dilute acid oxidant solution can be used effectively to clean the metal gate electrode or to form an undercut on a metal gate layer of the metal gate electrode.
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