Methods of forming high aspect ratio openings. The method comprises removing a portion of a dielectric material at a temperature less than about 0° C. to form at least one opening in the dielectric material. The at least one opening comprises an aspect ratio of greater than about 30:1. A protective material is formed in the at least one opening and on sidewalls of the dielectric material at a temperature less than about 0° C. Methods of forming high aspect ratio features are also disclosed, as are semiconductor devices.
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