| 摘要 |
A process for device fabrication, comprising the steps of forming a dielectric material region on a silicon substrate, forming a first amorphous silicon or polysilicon region on the dielectric material region, implanting one or more dopants in the first amorphous silicon or polysilicon region, and, subsequent to implanting the one or more dopants in the first amorphous silicon or polysilicon region, forming a second amorphous silicon or polysilicon region on the first amorphous silicon or polysilicon region. Typically, a refractory metal silicide layer is formed over the silicon, and such silicide is optionally formed by a salicide process. The second silicon region makes it more difficult for the implanted dopants to reach the silicide layer, and thereby reduces undesirable lateral diffusion of dopants in the silicide and accompanying cross-doping. The buried nature of the dopants in the silicon further reduces the amount of lateral diffusion within the silicon, regardless of the gate material. In addition, the benefits of a relatively thin gate dielectric are realized. Further, the reduced annealing times and temperatures necessary for dopant drive-in and activation result in improved control of device threshold voltage, on- and off-current, and channel and source/drain dopant profiles. |
