Study on Optimum Condition for Fabrication of Tapered Ion-Implanted Layer in Hybrid Type Bubble Memory Devices

Methods for precise formation of tapered ion implanted layers for use as propagation tracks in 4 Mbit magnetic bubble memories were discussed. After forming a mask pattern using multi-layer resist methods, a resist pattern was formed on the propagation line connector, and heat treated. This heat treatment changed the resist cross-section angle ¿ and the pattern lengthening l; their dependences on the heat treatment temperature were determined. Optimum precisions of ¿ = 48 ± 2.3° and l = 0.43 ± 0.02 ¿m were obtained at 170°C without ultraviolet exposure.