Templates for highly ordered SiGe-QD arrays for single photon detection

Two and three dimensional SiGe-QD-arrays can be regarded as a test-system for artificial crystals, as they also can be utilized as single photon detectors. While arrays with randomly distributed SiGe-QD can easily be grown on plain silicon surfaces, the fabrication of ordered arrays with pitches done to a few 10 nm is challenging: to facilitate Template Assisted Self Assembled growth of SiGe-QD in MBE, ordered arrays of seed holes have to be etched into the silicon substrate. EUV-interference lithography can be employed, but here no spatial relation to previous or later process steps is possible. In this work contrast and resolution of ZEP 520A-7 is investigated in terms of development temperature, duration and acceleration voltage during e-beam exposure to obtain laterally ordered well localized SiGe-QD-arrays. By increasing acceleration voltage from 50 kV to 100 kV contrast can be improved by a factor of 1.9, shifting the resolution from 40 nm pitch seed hole arrays etched in silicon to 30 nm.