FinFET Source/Drain Epitaxy for Non-Faceted Contact Surfaces

The patent applies parameter changes by modifying deposition conditions (temperature, pressure, gas flow rates) and etching parameters (etchant composition, temperature, time) to transform the surface morphology from faceted to non-faceted. Specifically, the multi-step process uses different temperature ranges (600-800°C for deposition, 700-900°C for etching) and pressure conditions to control crystal growth and remove facets, thereby reducing contact resistance while maintaining manufacturing efficiency

The patent extracts the harmful faceted surfaces through selective etching processes. The first etch back process specifically targets and removes the faceted top surfaces that formed during deposition, separating the unwanted facet structure from the desired epitaxial region. This extraction eliminates the source of high contact resistance while preserving the underlying beneficial epitaxial structure

The patent segments the deposition and etching processes into multiple distinct steps with specific parameters for each stage. The deposition is divided into initial growth and final capping stages, while etching is segmented into first etch back (removing facets) and second etch back (final planarization). This segmentation allows each step to be optimized independently, managing overall process complexity while achieving the desired non-faceted surface with increased contact area

The patent performs preliminary actions by forming a sacrificial oxide layer before deposition and using it as a mask during etching. The oxide layer is formed in advance to define the contact region boundaries, and the preliminary deposition creates a buffer layer that protects underlying structures. These preliminary actions establish the framework for subsequent processing, enabling precise control of contact landing area without proportionally increasing overall process complexity