The cross-section SEM micrographs in Fig. The SEM micrographs in Fig. illustrate the step coverage of an AlN thin film deposited in the same type of trench structure but now with a co-flow of Kr during the process. A film thickness of 24 nm at the top surface was achieved after 500 ALD cycles with a co-flow of Kr, increasing to 39 nm at the bottom of the trench. This corresponds to SC = 1.6. As noted, the addition of Kr reduced the GPC at the top surface of the trench, while maintaining the GPC at the bottom of the trench. This is similar to our previous result with Xe addition to a CVD process for B4C where the growth rate also decreased at the top of the trenches upon addition of Xe. It can be noted that in that study we observed a somewhat higher growth rate at the bottom of the trenches.