Suppressing the Formation of Cone Structures in Chemical-Vapor-Deposited Aluminum Nitride/Titanium Nitride Films

Cone structures are sometimes observed in aluminum nitride/titanium nitride (AIN/TiN) composite films formed by chemical vapor deposition (CVD). In this study, we determined the formation mechanism of cone structures by looking at such films deposited on Si substrates. We found that the mechanism can be explained by changes in the deposition rate due to composition differences in the growing surfaces, rather than by inhomogeneities in the original substrate surface. We then used this discovery to develop a technique to suppress cone structure formation, i. e., deposition of an interlayer before the deposition of the composite. To validate our technique, we then successfully suppressed the formation of cone structures in AIN/TiN films by depositing a TiN interlayer on the substrate before the deposition of AIN/TiN.