The effect of the Kr co-flow was further studied using lateral high aspect ratio (LHAR) structures with a removable top-membrane. Top-view SEM was used to analyze the AlN deposition in the LHAR structures after removing the top membrane (Fig. ). The analysis shows that both with and without the Kr co-flow, the AlN deposition depth reached 42 µm into the structure in both 150 µm and 75 µm deep structures. This is equivalent to an aspect ratio of The bottom row presents higher magnification images.