Plasma etching in integrated circuit manufacture—A review

Plasma etching, the selective etching of material by reaction with chemically active radicals in a glow discharge, is dry and clean, and offers process simplification and improved dimensional tolerances compared to existing wet‐chemical‐etching processes in semiconductor integrated circuit (IC) device fabrication. In this paper previously published work on plasma etching and apparatus is reviewed, new processes and techniques for Al and Al–Si plasma etching and for the precise control of etchrates and detection of etchcycle endpoints are reported, and plasma etching and stripping are shown to be fully compatible with silicon gate, metal–oxide–semiconductor (MOS) device processing in a new ’’fully plasma‐etched ion‐implanted’’ 2‐μm channel‐length CMOS process. It is concluded that plasma etching and stripping technologies can have a significant impact on MOS manufacturing, in improving the tolerances and yield of conventional geometry devices with 4‐μm minimum linewidth, and in improving the resolution to help evolve the next generation of high‐density, high‐performance short‐channel devices. However, for a thorough exploitation of plasma etching in IC manufacturing, there remains a need for further efforts to obtain (a) a more complete understanding of the fundamentals of plasma‐etching processes and (b) simple automatic apparatus for fast uniform etching with precise endpoint detection and control.