Measurement of the effect of temperature on stress distribution and deformation in multilayer optical thin film structures

Methods of predicting the deformation and stress distribution in multilayer optical thin film structures are investigated. The thin film layers include materials of various thermal expansion coefficients, elastic moduli, and melting temperatures. Each layer is deposited at a different temperature, causing complex thermal and deposition stresses throughout the structure. In addition, because the deposition temperatures of some of the layers are high, stress relaxation and plastic flow may occur in materials with low melting temperatures. A combination of theoretical predictions and experimental measurements is used to measure and quantify the deformation caused by residual and thermal stresses in the films as well as any plastic deformation that may have occurred