Specific Process Knowledge/Characterization/Stress measurement/Stress origins: Difference between revisions
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= | =Metal film stress dependence on composition and growth conditions= | ||
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Notice that you can increase the atomic mobility (and reduce the tensile stress) by increasing the temperature. This trend is clearly shown in e.g., Abermann's data. In sputtering you can also increase the mobility of the atoms in the growing films by decreasing the pressure and adding a bias to accelerate the sputtered atoms towards the growing film. In evaporation you can in some cases also add mobility to the growing film by ion bombardment during the deposition. | Notice that you can increase the atomic mobility (and reduce the tensile stress) by increasing the temperature. This trend is clearly shown in e.g., Abermann's data. In sputtering you can also increase the mobility of the atoms in the growing films by decreasing the pressure and adding a bias to accelerate the sputtered atoms towards the growing film. In evaporation you can in some cases also add mobility to the growing film by ion bombardment during the deposition. | ||
Another way to summarize in general – based on tutorial articles by E Chason and coauthors: | |||
* Very thin films exhibit tensile stress (island coalescence) | |||
* Thicker films can be tensile or compressive | |||
* Tensile tends to occur in low-mobility materials | |||
* More tensile with fast deposition at low temperature | |||
* Examples Ni, Cr | |||
* Compressive stress tends to be in high-mobility materials | |||
* More compressive with slower deposition at higher temperature | |||
* Can become less compressive as temp drops at end of deposition | |||
* Examples Au, Ag, Cu | |||
==Models of thin film growth and stress== | ==Models of thin film growth and stress== | ||