Easy process for fabrication of high-reliability DC-SQUIDs

A process to fabricate high-reliability DC-SQUIDs for the study of biomagnetism on 4-in silicon wafers by minimizing the steps of the fabrication process is discussed. Al films were used for the shunt and damping resistors to decrease the number of materials used in the fabrication. The large beta L DC-SQUID device was adopted to increase the reliability of the process because of the small number of input coil turns needed. The reliability of the fabricated devices was tested by examining their current-voltage and flux-voltage characteristics. These characteristics were in close agreement with the calculated values. The critical current and the modulation depth of about 200 DC-SQUIDs across a single wafer agreed within +or-5%.<
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