In this SOP we present a release process that was tested for structures made of aluminum and lithium niobate that are partially masked by SPR-3612, but the process should be applicable to other materials/photoresist, provided they are not etched by SF6.
One can accurately determine horizontal etch rates by looking at unreleased structures with an overhead SEM. However, this will only work with materials that one can see through with the SEM, such as thin film aluminum and similar materials with low atomic number.