Growth Inhibition To Enhance Conformal Coverage In Thin Film Chemicalvapor Deposition

摘要

Many important technological applications depend crucially on the ability to deposit conformal (i.e., uniformly thick) films on substrates having 3-dimensional relief features. For example, in the microelectronics industry, conformal deposition processes are needed to line and fill trenches and vias as part of the fabrication of capacitors, interconnects, and other key device components. Physical vapor deposition (PVD) processes such as sputtering, which are widely used to grow thin films, are unfortunately unable to afford good conformality inside features with aspect ratios (ARs) above ～5. For this reason, the International Technology Roadmap for Semiconductors predicts that it will be necessary to replace PVD with chemical vapor deposition (CVD) and atomic layer deposition (ALD) methods to line and fill features having the increasingly large ARs that will be characteristic of future generations of integrated circuits. ALD is inherently conformal, but the film growth rates are very low (typically < 0.2 nm/cycle), especially in high AR features. In contrast, CVD can routinely deposit films much more rapidly, but a key challenge is how to ensure high conformality while maintaining the high growth rates.rnThe conformality of the growth process in a feature of given AR depends on the reactive sticking probability (β) of the gas phase precursor on the film growth surface (Supporting Information, eq 1), lower values of β giving rise to better conformality because the precursor will diffuse deeper into the feature before reacting.