Transistors with increased mobility in the channel zone and method of fabrication

摘要

A semiconductor transistor structure with increased mobility in the channel zone and a method of its fabrication are described. A semiconductor substrate having a first dopant is formed. A diffusion barrier layer having a second dopant is formed on the semiconductor substrate to suppress outdiffusion of the first dopant. Next, a semiconductor layer having substantially low dopant concentration relative to the first layer is epitaxially grown on the diffusion barrier layer. The semiconductor layer defines a channel in the semiconductor transistor structure. The low dopant concentration in the semiconductor layer increases the mobility of the carriers in the channel of the semiconductor transistor structure. A gate electrode and a gate dielectric are formed on the semiconductor layer with the low dopant concentration.