Simplified Fabrication On Al/AlOx/Al Tunnel Junction

Superconducting Josephson junction, as the basic unit of superconducting qubits, has excellent scalability, system controllability and long coherence time. So far, some integrated fabrications on Josephson junctions have been developed. Josephson junction system is widely researched in quantum computing areas.In this paper we studies the fabrication of Al/AlOx/Al tunnel junction. we have done a lot of work on exploring a simplified technique of fabricating Al/AlOx/Al superconducting tunnel junctions on high resistivity silicon substrate, which aims to reduce the complexity of the operation. Through photolithography, magnetron sputtering,etching and other technology, we have successfully fabricated the Al/AlOx/Al tunnel junction. The junction â… -â…¤ characteristic was measured at 0.3K, which shows that the energy gap voltage was 0.37 mV and the superconducting critical current density is about 12 A/cm2. We focused on the following work:1. The basic parameters of simplified fabrication were determined.2. Al films were deposited by magnetron sputtering. We tested the different effects of air pressure and sputtering power.3. The natural oxide layer was etched by ion beam milling. After measuring the etching effect on Al film and silicon substrate, appropriate etching time was confirmed.4. Some parts of the fabrication process should be optimized to ensure the stability of sample properties. We have researched the negative effects of these steps and put forward to some improvement projects.