Scanning electron beam lithography for fabrication of magnetic bubble circuits

A high-resolution technique is described for the experimental fabrication of Permalloy patterns for magnetic bubble circuits having linewidths as small as 3000 A. The system includes a computer-controlled electron beam, automatic registration, a modified field-stitching method, and exposure control to compensate for proximity effects. Patterns are formed either by electroplating or by evaporation. The system can be used either for directly writing on bubble wafers or for fabricating masks for x-ray or conformable-mask printing.