Self-alignment techniques for GaAs MESFET i.c.s

The current status of self-alignment in GaAs is reviewed and the technological impact of the various different techniques assessed. The discussion centres around the gate-priority and ohmic-priority self-aligned n+implantation schemes. The advantages and disadvantages of each approach are discussed in terms of both process complexity and ultimate performance. The short channel effect, orientation effect and planar channelling are described as potential problem areas for short gate length self-aligned devices and the ability of each process to alleviate these effects is considered.