Effects of Metallic Impurities upon thin Gate Oxide Integrity and Related Bulk Properties in CZ Si
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In this study, we investigated effects of various well-known metallic impurities such as Fe, Cu, and Al (contaminated by a spin coating method with concentration levels ranged from 1 × 1010 to 1 × 1010 atoms/cm2) upon: 1) thin oxide integrity; 2) total oxide charge; and 3) various bulk electrical and structural parameters. The oxide integrity was determined from the breakdown field strength and the time dependent dielectric breakdown characteristics of MOS capacitors with the thermally-grown 23 nm thick SiO2 films. In addition, in order to correlate bulk structural and electrical parameters with the oxide integrity, two different types of lifetime measurements were carried out for these wafers. Some of these samples were further characterized for metal-induced surface and bulk microdefects by transmission electron microscopy and thermal wave modulated optical reflectance (using both mapping and imaging modes). Based upon our oxide integrity and bulk electrical and structural characterization data, we conclude that Fe is the most harmful metallic impurity among the three metallic elements investigated in this study.
KeywordsContamination Level Thermal Wave Gate Oxidation Optical Reflectance Metallic Impurity
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