wafer plane, the relationship between the stress state and the {111} planes could not be altered ... structures fabricated on (001) single-crystal silicon films. Journal of Applied Physics 2009 ...

or plane, identified by a bracketed number, such as (100), (110) or (111). "If you etch silicon using fluorine gas, the etching proceeds along (100) and (110) crystal planes but does not etch (111 ...