High mobility enhancement mode FET

摘要

A novel semiconductor transistor is presented. The semiconductor structure has a MOSFET like structure, with the difference that the device channel is formed in an intrinsic region, so as to effectively decrease the impurity and surface scattering phenomena deriving from a high doping profile typical of conventional MOS devices. Due to the presence of the un-doped channel region, the proposed structure greatly reduces Random Doping Fluctuation (RDF) phenomena decreasing the threshold voltage variation between different devices. In order to control the threshold voltage of the device, a heavily doped poly-silicon or metallic gate is used. However, differently from standard CMOS devices, a high work-function metallic material, or a heavily p-doped poly-silicon layer, is used for a n-channel device and a low work-function metallic material, or heavily n-doped poly-silicon layer, is used for a p-channel FET.

主权项

1. A semiconductor field effect device structure comprising:
a source region and a drain region; a channel region between said source and drain regions; a semiconductor barrier region under said channel region; a dielectric layer extending over at least a portion of said channel region; a gate extending over said dielectric layer;
wherein said gate is in physical contact with said dielectric layer;wherein said gate is at least partially overlapped with at least one of said source and drain regions;wherein said channel region has a dopant concentration less than about 5×1016 cm−3;wherein said gate has a work-function substantially equal or greater than the sum of the electron affinity and half energy-gap of said channel region, when said semiconductor field effect device is a n-channel device;wherein said gate has a work-function substantially equal or lower than the sum of the electron affinity and half energy-gap of said channel region, when said semiconductor field effect device is a p-channel device, andwherein said semiconductor field effect device structure is an enhancement mode field effect device.