We have developed a fabrication process based on Chemical Mechanical Polishing (CMP) for the sub-micron NbN Josephson junctions on single-crystal MgO substrates. The NbN junctions were fabricated with epitaxial NbN/AlN/NbN trilayers deposited by reactive DC magnetron sputtering. The top electrode of the junction was exposed using CMP to contact the NbN wire without opening the submicron via through the dielectric. It has produced submicron NbN junctions with areas as small as 0.09 μm². We have fabricated NbN tunnel junctions with a wide range of critical current density J_c. The NbN junctions show excellent Josephson tunneling characteristics, the gap voltage V_g is 5.8 mV and the quality factor R_sg/R_n is 12 for the junctions with a J_c of 10.7 kA/cm², and V_g is 5.3 mV and R_sg/R_n is 4 for the junctions with a J_c of 150.5 kA/cm². The 1000-junction arrays were fabricated and their I-V characteristics were measured, critical current uniformity was obtained and the standard deviation is about 5%. The high J_c sub-micron NbN junctions will be helpful in developing large-scale NbN SFQ circuits with high operating frequency.

我们开发了一种基于化学机械抛光 (CMP) 的制造工艺，用于单晶 MgO 基板上的亚微米 NbN 约瑟夫森结。NbN 结是通过反应直流磁控溅射沉积的外延 NbN/AlN/NbN 三层制成的。使用 CMP 暴露结的顶部电极以接触 NbN 线，而无需打开穿过电介质的亚微米通孔。它已生产出面积小至0.09 μm ^{2的亚微米NbN 结}。我们制造了具有宽范围临界电流密度J _{c的 NbN 隧道结}。NbN结表现出优异的约瑟夫森隧道特性，其间隙电压V _g为5.8 mV，品质因数R _sg / R _n为12， J _c为10.7 kA/cm ²， V _g为5.3 mV， R对于J _c为 150.5 kA/cm ²的结， _sg / R _n为 4 。制作了1000个结的阵列并测量了它们的I - V特性，获得了临界电流均匀性，标准偏差约为5%。高J _c亚微米NbN结将有助于开发具有高工作频率的大规模NbN SFQ电路。