Extended Data Fig. 5: Geometry to be etched.
Illustration of the cross-section for a patterned PPA layer spin-coated on an hBN flake. The etch time can be calculated by the following formula: \({\rm{Etch\; time}}={\rm{strike\; time}}+\frac{{\rm{cushion}}+2A+D}{{{\rm{rate}}}_{{\rm{PPA}}}}\) where the strike time is how long it takes for the plasma to be generated after the etching recipe is started (~7 s in our system), the cushion and pattern amplitude A are typically in units of nanometers, D is a user-defined offset (typically in nanometers) that can be positive or negative to engineer a ‘miss’ to one side of the under-etch–over-etch balance if it is critical for the process and ratePPA is the etch rate of PPA (typically in units of nanometers per second).
