Texas Tech University Stress arises in thin film materials whenever they are grown in heteroepitaxial contact. This is frequently the case in microelectronic and optoelectronic devices. The stress can come from lattice constant mismatch between the substrate, say, and the adjacent layer being epitaxially deposited.
Stress can also stem from differences in thermal expansion coefficients of different layers.
When layers are patterned, the stress takes on a local character and can be enhanced beyone what is necessary to cause cracking in thin films. At lower levels of stress, impurity diffusion can be enhanced or retarded, and it can influence subsequent deposition rates. In this presentation, I will summarize stress measurements made using micro-Raman imaging. This technique is capable of mapping stress with a spatial resolution of 1 - 2 microns. There are few competing methods.