Epitaxial Source/Drain Layout on Dielectric Substrates for Leakage Control

The patent extracts the source of leakage current and parasitic transistor formation by removing the semiconductor substrate and replacing it with a dielectric substrate. This eliminates the parasitic conduction paths that exist in conventional semiconductor substrates, directly addressing the harmful effects while maintaining device functionality through epitaxial source/drain structures.

The patent introduces a dielectric substrate as an intermediary between the epitaxial source/drain structures and the underlying support. This dielectric layer acts as a mediator that prevents direct electrical contact that would cause leakage, while still providing mechanical support and enabling the formation of high-performance multigate devices.

The patent transitions from planar gate control to three-dimensional multigate control by forming gates that wrap around the channel in multiple dimensions. This vertical and lateral gate wrapping provides enhanced electrostatic control over the channel, effectively suppressing short-channel effects even as devices continue to scale down in size.

The patent employs composite material structures including epitaxial semiconductor layers with different compositions (e.g., SiGe source/drain regions with silicon channels) to achieve both scaling and control. The engineered material composition gradients and heterostructures enable improved carrier mobility and gate control simultaneously.

The patent performs preliminary actions by forming the epitaxial source/drain structures with integrated strain features during the early fabrication stages, before gate formation. This preliminary strain engineering is built into the epitaxial growth process itself, allowing subsequent processing steps to proceed with standard techniques while the performance benefits are already established.

The patent utilizes parameter changes in the epitaxial growth process, such as varying temperature, pressure, and composition gradients, to create optimized source/drain structures with built-in strain. By controlling these growth parameters, the patent achieves enhanced carrier mobility and reduced leakage without requiring additional complex post-processing steps.