Asymmetrical transistor with a source region that is very heavily-doped and the drain region is doped with a high concentration and low concentration

摘要

To provide asymmetrical IGFET that includes a source region is very heavily-doped drain region to be doped (57) in a high concentration and low concentration summary]. Preferably, the channel junction is brought from the source region, which is very heavily-doped drain region is lightly doped. Forming on a substrate a gate that includes the steps of providing a semiconductor substrate, the opposite side walls of the first and second method of making the IGFET, is lightly doped by applying a first ion implantation The high concentration almost the whole of the source region doped to a low concentration without the step of injecting a substrate source and drain regions that, by applying a second ion implantation to dope the drain region is lightly doped By applying a step change in the source region is doped, ion implantation, the third and, instead of the source region that is very heavily-doped source region is heavily doped, the lower the drain side spacer without doping a portion of the drain region is lightly doped, and a step of changing the drain region that is heavily doped portion of the drain region is lightly doped outside of the drain side spacer. Advantageously, IGFET low source - a drain series resistance, I want to reduce the hot-carrier effect.