Recent advances inultra-high-speed HEMT technology

Current status and recent advances in high electron mobility transistor (HEMT) technology for high-performance VLSI are presented with a focus on material, self-alignment device fabrication, and HEMT LSI implementations. HEMT is a very promising device for ultra-high-speed LSI/VLSI due to the supermobility GaAs/AlGaAs heterojunction structure. The technological challenges for large-scale integration are discussed with the refined HEMT with self-aligned gate structure, controllability of device parameters, and MBE material problems. Master-slave flip-flop divide-by-two circuits achieved an internal logic delay of 22 ps per gate at 77 K at a fan-out of about 2, roughly three times faster than that of GaAs MESFET technology. HEMT has already made it possible to develop a 4 kbit static RAM's and 1.5 kgate gate array, demonstrating high-speed operations. With submicron gates, as well as advanced material technologies, a HEMT 64 kbit static RAM with subnanosecond access operation and 10 kgate logic LSI with subhundred-picosecond logic delays will be achieved.