![]() ![]() In particular, stresses can originate from processes within the interior of the grains throughout the film or they can arise from processes at the grain boundaries. However, many thin films are polycrystalline so that the distribution of stress can be more complex. The preceding discussion of the Stoney equation assumed that the stress at each height ( z), σ xx( z), in the layer is uniform in the plane of the film. MEASUREMENT OF THIN FILM STRESS USING WAFER CURVATURE This also highlights the need for systematic studies in order to determine the range of validity of the model and effects that it cannot explain. The model is compared with experimental results to show how its predictions are consistent with observations in a number of different systems. V, a kinetic model is described that combines the growth-related mechanisms into a set of rate equations to describe the dependence of the stress evolution on the parameters considered in Secs. The emphasis is on explaining intrinsic stress, i.e., stress related to the processes of film growth and microstructural evolution, but some other mechanisms (thermal expansion, epitaxial mismatch, and energetic deposition) are considered as well. ![]() These results are used to motivate the discussion of underlying stress generating mechanisms in Sec. The results from these studies are used to identify common trends for the dependence of the stress on growth rate, atomic mobility, temperature, surface morphology, grain size, etc. Section III describes phenomenology that has been seen for a number of studies (i.e., different materials systems, different processing parameters, and stress changes during growth interrupts). A description of the multi-beam optical stress (MOSS) measuring technique and its sensitivity is also discussed. The analysis is extended to include consideration of curvature from stress in polycrystalline or non-uniform films. The wafer curvature method for determining thin film stress is described first, with emphasis on how the curvature is related to the distribution of stress throughout the thickness of the layer. The manuscript is organized in the following way. The model results are compared with the experiments to show how this approach can explain many features of stress evolution. This leads to a kinetic model that can predict the dependence of the stress on multiple parameters. To develop a fuller understanding, we consider the kinetic factors that determine how much each of these processes contributes to the overall stress under different conditions. ![]() The corresponding stress-generating mechanisms that have been proposed to explain the data are also described. Examples from multiple studies are discussed to illustrate how the stress depends on key parameters (e.g., growth rate, material type, temperature, grain size, morphology, etc.). The results are used to describe a comprehensive picture that is emerging of what controls stress evolution. In this work, we review how thin film stress is measured and interpreted. Better understanding and control of film stress would lead to enhanced performance and reduced failures. Residual stresses are indirectly calculated by measuring the existing material strains, which are generally measured by mechanical or x-ray methods.Residual stress is a long-standing issue in thin film growth. Shot peening typically uses a metal or glass material, while laser peening uses high-intensity beams of light to induce a shock wave that propagates deep into the material. Mechanical methods include shot peening and laser peening. Heated parts is known as stress relief bake, and cooled parts is known as cryogenic stress relief. The thermal method involves uniformly changing the temperature of the entire part through heating or cooling. All methods involve processing the part so the whole stress is relieved. When undesired residual stress from prior metalworking operations is present, the amount of stress may be reduced through the use of several methods classified as thermal or mechanical (nonthermal) methods.
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