Patent ID: 8524563

Claim:
A method for forming a MOSFET, comprising: providing a substrate having a first surface; forming a control gate of the MOSFET overlying the first surface and insulated therefrom, the control gate having thereon first and second initial dielectric sidewalls; etching an initial cavity in the substrate from the first surface proximate the second sidewall of the gate; etching proximate the first sidewall of the gate, a first cavity in the substrate from the first surface to a first depth and having a first portion extending under the control gate at a first depth from the surface; etching proximate the second sidewall of the gate, a second cavity in the substrate from the initial cavity to a second depth and having a second portion extending under the control gate toward the first portion at a second depth from the first surface different than the first depth, wherein etching the first cavity and etching the second cavity continue until the first and second portions laterally overlap; and refilling the first and second cavities with semiconductor containing material, wherein at least one of the first and second cavities is refilled with a material having a second lattice constant different than a first lattice constant of the substrate between the first and second cavities, thereby forming source-drain regions of the MOSFET.