Mechanically Strained, High Mobility, Strained-Si Devices

The aim of this effort is to inexpensively produce high performance strained-Si devices. The idea is to introduce strain into the Si lattice mechanically, and not via lattice mismatched, layered, heterostructures. Strain will be introduced by curving the ICs around a cylindrical packaging form. Using only standard fabrication techniques, integrated circuitry will be processed on thin single crystal Si membranes (20 - 50 microns thick). During the fabrication process, the membranes will be supported on standard Si wafer substrates and de-mounted afterwards. These flexible membranes can then be bent around cylindrical supports inducing uni-directional -tensile-strain. Enhanced electronic effects (mobility etc.) will be evident in devices which are appropriately aligned. Mechanically inducing the strain will circumvent the inherent problems in heterostructure fabrication. Initial calculations indicate the defect density will also be substantially reduced as the uni-directional-strain required for enhanced mobility is lower than that associated with dislocation formation. Mechanically straining the lattice after IC processing offers the possibility of a wide range of high speed devices in strained-Si, both unipolar and bipolar which are difficult to fabricate within the geometric confines of epitaxial device design. The applications are therefore in, inexpensive, high speed, strained-Si Devices.