Paper TF-ThM12
Enhancing the Inherent Area-selective ALD of TiO₂ using BCl₃

Thursday, November 2, 2017, 11:40 am, Room 21

Area selective deposition of thin film becomes increasingly important as semiconductor industries require shorter node than 10nm scale to alleviate trade-offs between performance and power consumption. Since inherent substrate-dependent selectivity shows relatively narrow selective window, enhancing procedure is required. TiO₂ atomic layer deposition (ALD) using titanium tetrachloride (TiCl₄) and water has been observed to selectivity deposit TiO₂ on Si-OH preferentially over Si-H surfaces. However, the selectivity is lost after initial incubation cycles. In an attempt to better understand selectivity loss mechanisms, we studied the role of surface hydrophobicity and found that the incubation period increased as the contact angle of the initial substrate surface also increased. Furthermore, we incorporated BCl₃ into our TiO₂ ALD sequence to further enhance the overall selectivity. Through the ellipsometry thickness measurement, TiO₂ ALD with BCl₃ shows more delayed TiO₂ growing on Si-H without delaying on Si-OH. Using quartz crystal microbalance (QCM) we show that BCl₃ appears to impede TiO₂ growth, rather than significantly etching TiO₂. Finally, we provide evidence that the ability to effectively impede TiO₂ deposition on Si-H without significantly reducing deposition on the Si-OH surface depends on the amount and frequency of BCl₃ dosing. This work ensures better selectivity than previous result.