The dependence of channel length on channel width in narrow-channel CMOS devices for 0.35-0.13 μm technologies

We have found that narrow-channel PFET´s do not have the same effective channel length as wide PFET´s with the same polysilicon length. Narrow PFET devices are longer than their wide counterparts by 20-40 nm while narrow NFET devices are negligibly different from wide NFET´s. This phenomenon occurs in a wide variety of technologies, from 0.13 and 0.18 μm technologies with extension/halo devices to a 0.35-μm technology with simple abrupt-junction devices. Depending on the details of the short-channel rolloff behavior, this phenomenon may result in apparent anomalous narrow-channel threshold voltage behavior. We suggest that the modification of the boron redistribution by the mechanical stress imposed by the bounding isolation SiO₂ may explain the effect.