The architecture of modern semiconductor devices requires deposition on, and even filling of, topologically very complex structures with films of various materials with different properties The challenge of depositing these films increases with the aspect ratio (AR), i.e., the ratio of depth to width, as well as with smaller scale of the features. The success of the film deposition is typically measured by the conformality of the film, which in turn is quantified by the step coverage (SC), defined as the film thickness at the bottom of the feature divided by the film thickness at the top of the feature. For perfect conformality, the film is as thick at the bottom as it is at the top, i.e., SC = 1. The best approach to deposit conformal films is often by atomic layer deposition (ALD). Since ALD uses self-terminating surface chemical reactions, an ALD process will be highly conformal if given enough time for the surface reactions to saturate all surfaces. However, ALD processes are not available for all materials. Carbides are one example of materials systems where only a few ALD processes have been reported due to the lack of carbon precursors rendering self-terminating surface chemistry. If the surface chemistry is not self-terminating, the deposition is instead referred to as chemical vapor deposition (CVD). Most CVD processes afford sub-conformal films with SC < 1 due to the less controlled surface chemistry. Very effective strategies for controlling the gas transport and reaction probabilities inside high AR features have been demonstrated, allowing CVD to not only deposit conformal films (SC = 1), but also superconformal films (SC > 1). The deposition rate in CVD depends on the flux of film forming species and energy supplied to the surface. In high AR recessed features, the challenge is to maintain a uniform flux over the surface with supply of film forming species from the opening of the features. Inside the features, the partial pressure of film forming species decreases the farther away from the nominal opening, rendering a higher incident flux with a higher deposition rate at the feature opening which leads to SC < 1. The reaction probability can be lowered by using precursors with low sticking coefficients or by adding a surface inhibitor . These two methods will promote gas phase diffusion down the feature and increase the SC. In CVD processes using two precursors, partial pressure tuning of precursor gases can also improve the SC in high AR features, albeit with the risk of affecting the compositional homogeneity of the film.