Tip Deflection of a Thermal Bimorph Cantilever Beam with Different Geometrical Structures

The residual stress is often due to a thermal mismatch in the thermal expansion coefficient (CTE) between the two materials. This phenomenon causes device failure such as curling, buckling, and also fracture upon releasing. Hence, strategies are needed to minimize the effect of residual stress on the induced beam bending upon release of the device. In this paper, four different geometrical structures are studied theoretically and simulated. The stress level is deduced by measuring the deflection of the beam. The result has shown that the beam with Al and SiO ₂ strip arranged alternately as the top layer and SiO ₂ as the bottom layer have the least downward deflection upon applied temperature. For T = 50 K, deflection of 0.8425 μm is measured. Simulation-based of varying thickness also show that having thicker SiO ₂ (with a similar total thickness of the beam) contribute to smaller downward deflection and least percentage error between theoretical and simulation result. Surface stress analysis also shows that the stress measured is 107.86 MPa, which is lower than the yield strength of Al and SiO ₂ materials.