Observation of ultraslow stress release in silicon nitride films on CaF2

Silicon nitride thin films are deposited by plasma-enhanced chemical vapor deposition on (100) and (111) CaF2 crystalline substrates. Delaminated wavy buckles formed during the release of internal compressive stress in the films and the stress releasing processes are observed macroscopically and microscopically. The stress release patterns start from the substrate edges and propagate to the center along defined directions aligned with the …