A model for anomalous short-channel behavior in submicron MOSFETs

• Published in: IEEE electron device letters 1993-12, Vol.14 (12), p.575-577
• Main Authors: Hanafi, H.I., Noble, W.P., Bass, R.S., Varahramyan, K., Lii, Y., Dally, A.J.
• Format: Article
• Language: English
• Subjects: Annealing; Applied sciences; Doping profiles; Electronics; Electrostatics; Exact sciences and technology; FETs; MOS devices; MOSFETs; Oxidation; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductor process modeling; Threshold voltage; Transistors
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/55.260794

Experimental data and simulation results for submicron MOSFETs are reported and used to support a physical explanation for two important anomalies in the dependence of device threshold voltage on channel length. They are the widely observed increase in threshold voltage with decreasing channel length (roll-up), and the more recent observation that the ultimate threshold voltage decrease (roll-off) occurs at a rate which is far in excess of that which can be explained with conventional models of laterally uniform channel doping. A model that attributes roll-up as well as roll-off to lateral redistribution of doping near the source and drain junctions is proposed. This lateral redistribution is caused by crystal defects formed during post-source/drain-implant anneal. The resulting profile consists of an enhancement of background doping adjacent to the junction edge, bounded by a depression of the doping farther into the channel.< >