Process for fabricating conformal Ti-Si-N and Ti-B-N based barrier films with low defect density

摘要

A CVD process for Ti--Si--N or Ti--B--N films wherein a single feed gas (preferably TDMAT) serves as the source for titanium and nitrogen, and another feed gas is used as the source for silicon or boron. This avoids gas-phase particulate nucleation while providing good conformality. When the required thickness has been deposited, the silicon or boron feed gas continues to flow for some time after the titanium/nitrogen or titanium/boron source gas has been turned off. This results in a Ti--N film with a Si-rich or B-rich surface, which is conformal and has a low defect density. In a second embodiment, a single feed gas, such as TDMAT, is thermally decomposed to form a Ti--N layer. A post-deposition anneal is performed in a gas which supplies silicon or boron, incorporating these materials into the layer. The incorporation of silicon or boron into the layer minimizes the absorption of oxygen into the films, and therefore stabilizes the resulting films. The Si- rich or boron-rich surfaces are also helpful in wetting Al and enhancing adhesion to Cu, therefore are advantageous for advanced metallization application. Compared with the sputtering method, this invention offers a process for depositing films with much better step coverage and easier control of Si/Ti ratio. Compared with the TDEAT+NH.sub.3 +SiH.sub.4 method, this invention eliminates the gas phase reaction between Ti source and NH.sub. 3.