Epitaxial CrN(001) layers, 57 and 230 nm thick, were grown on MgO(001) at 700 °C by ultra-high-vacuum magnetron sputter deposition in pure N@sub 2@ discharges. An oblique deposition angle @alpha@ = 80° was utilized to purposely increase the effect of atomic shadowing on surface morphological and microstructural evolution. The layers are single crystals with a surface morphology that is characterized by dendritic ridge patterns extending along orthogonal <100> directions superposed by square shaped super mounds with <100> edges. The ridge patterns are due to a 2D growth instability related to a gradient in the adatom density while the supermounds form due to atomic shadowing. The supermounds protrude out of the surface and capture a larger deposition flux than the surrounding layer. This leads to both vertical and lateral growth and the formation of inverted pyramids that are epitaxially embedded in a single crystalline matrix. The inverted pyramids are terminated by 1-3 nm wide tilted voids that form nanostaircases due to kinetic faceting along orthogonal {100} planes.