On modeling of the self-aligned field implanted MOS devices with narrow widths

The IDS-VGScharacteristics of a narrow width MOS device-fabricated with self-aligned field implanted technology is markedly different from that predicted by the conventional theory. It has been observed that the threshold voltage and electrical channel width are functions of both gate bias and geometrical width. An explanation of this observation is given. The concepts of the effective threshold voltage and the effective channel width for a non-uniformly doped device are introduced, and a simple model developed which enables the determination of the doping profile along the channel width from a known IDS-VGSrelationship. In addition, a technique is described which enables an automatic plot of doping profile along the channel width, a technique which should prove invaluable for process control.