Mechanical Behavior of Single Crystal A1 (111) and Bicrystal Al (110) Films on Silicon Substrates

Single crystal Al (111) films and bicrystal Al (110) films have been deposited on bare Si (111) and (100) wafers using ion-cluster beam deposition. The stress in the films was determined using X-rays diffraction as the films were thermally cycled from room temperature to 400C. The (111) film exhibited nearly ideal elastic behavior as the stress was essentially linear with temperature. The (110) Al film yielded in compression at a lower temperature and stress than the (111) film and exhibited broad hillocks not found in the Al (111) film. During the second thermal cycle, both films behaved in a nearly ideal elastic fashion. Measurement of the strain relaxation in the films during the second thermal cycle showed that the (110) film relaxed significantly while the (111) did not relax.