Strainedchannel

Strainedchannel refers to a semiconductor device fabrication technique where mechanical strain is intentionally introduced into the channel region of a transistor to enhance its performance. This strain modifies the material's band structure, which in turn affects the mobility of charge carriers (electrons or holes) within the channel. Higher carrier mobility leads to faster switching speeds and reduced power consumption for the transistor.

There are two primary types of strain used: tensile strain and compressive strain. Tensile strain, which stretches the material, is typically applied to n-type transistors (NMOS) to increase electron mobility. Compressive strain, which squeezes the material, is generally applied to p-type transistors (PMOS) to increase hole mobility. This targeted application of strain allows for complementary performance improvements in CMOS (Complementary Metal-Oxide-Semiconductor) technology.

Several methods are employed to induce strain. One common approach involves using lattice-mismatched materials in the transistor's gate stack or source/drain regions. For example, depositing silicon-germanium (SiGe) alloys in the source and drain of a silicon transistor can induce compressive strain in the channel if the SiGe lattice constant is larger than silicon, or tensile strain if it's smaller. Another technique involves forming shallow trench isolation (STI) structures with specific geometries that exert mechanical stress on the channel.

The widespread adoption of strained silicon technology has been a significant factor in the continued scaling and performance improvement of integrated circuits, allowing for faster and more energy-efficient processors and other semiconductor devices.