SiGe Epitaxial Growth Selectivity and Morphology Control

The patent applies dynamics by making the growth conditions variable rather than static. Specifically, the growth temperature and halogen gas content are dynamically adjusted during the epitaxial growth process - starting at lower temperatures with lower halogen content to ensure good morphology, then increasing temperature and halogen content to achieve high growth selectivity. This temporal variation in growth parameters resolves the contradiction between morphology and selectivity.

The patent implements periodic action through multi-stage epitaxial growth with distinct phases. The process is divided into multiple periods: an initial growth period with controlled halogen content and temperature for morphology formation, followed by subsequent periods with increased halogen content for selective growth. This periodic adjustment of growth conditions allows both morphology and selectivity requirements to be met at different stages.

The patent uses dynamic temperature control during epitaxial growth. Instead of maintaining a constantly high temperature, the process starts at lower temperatures to preserve lattice matching and stress, then dynamically increases temperature to achieve selective growth. This temporal temperature variation allows the system to benefit from both low-temperature stress preservation and high-temperature selective growth.

The patent applies parameter changes by systematically varying multiple growth parameters including temperature, halogen gas content, and pressure throughout the epitaxial process. By changing these parameters in a coordinated manner - initially using lower temperatures and gradually increasing them - the patent achieves selective growth while maintaining adequate stress in the channel region.

The patent implements periodic action through staged growth periods with different temperature regimes. The process includes an initial period at lower temperatures where growth rate is sacrificed to prevent impurity diffusion, followed by subsequent periods at higher temperatures where growth rate is enhanced. This periodic temperature adjustment allows both low-diffusion and high-productivity requirements to be met at different stages.

The patent applies preliminary action by performing low-temperature growth first to establish a foundation layer with minimal impurity diffusion, before proceeding to high-temperature growth. This preliminary low-temperature stage prepares the structure in advance, preventing subsequent impurity contamination while allowing faster growth later.