For the testing of different etch parameters, so-called "easycleave" structures were etched and analysed. Easycleave, as shown in Figure , is a 1 cm by 2 cm piece of silicon wafer with a 50 nm thick chromium etch mask with arrays of apertures. The apertures are arranged with a 84.5°angle between the axis of the primitive lattice. This non-90°angle ensures that cleaving along a wafer crystal plane will always cleave through some of the pores, hence the name easycleave. The etch mask consists of arrays of circular apertures of 11 different diameters. For each diameter there are up to 7 arrays of different pore-to-pore pitches.