A new technique for fabrication of nano- and atomic-scale device elements and quantum systems which cannot be obtained by any other technology is proposed. The technique is based on the experimentally established possibility of creating atomically sharp-edged cracks of desired length and direction in a given layer of a heterostructure. Ultra-narrow (1 nm) and perfectly straight window-slits in the GaAs layer-mask of semiconductor structures and ultra-thin (2 nm) semiconductor membranes have been fabricated for the first time.