A comparative study of electronic transport properties of p-Si wafers intentionally contaminated with Fe was performed using infrared photothermal radiometry (PTR) and microwave photoconductance decay (µ-PCD). Strong correlations were found between PTR and µ-PCD lifetimes in a lightly contaminated wafer with no significant PTR transient behavior. The absolute PTR lifetime values were larger than the local averaged µ-PCD values, due to the different excitation wavelengths and probe depths. In a heavily contaminated wafer the µ-PCD and PTR lifetime correlation was poorer. PTR measurements were highly sensitive to Iron concentration, most likely due to the dependence of the bulk recombination lifetime on it. Rapid-scanned (non-steady-state) PTR images of the wafer surface exhibited strong correlations with both µ-PCD lifetime and Iron concentration images in both heavily and lightly contaminated wafers. For the lightly and uniformly contaminated wafer, PTR scanning imaging was found to be more sensitive to iron concentration and lifetime variations than µ-PCD images.
A novel method for reducing metallic contamination of silicon wafer surfaces and oxide layers during high temperature processing is described. It involves the application of an electric field across wafers exposed to oxidizing and inert annealing ambients. Secondary ion mass spectrometry, capacitance-voltage, and vapor-phase decomposition/total reflection X-ray fluorescence techniques were used to measure metallic contamination levels in the silicon oxide layers. Results indicate that a positive bias, applied to the silicon at high temperature, provides a significant reduction of Li, Na, and K content in the oxides, compared with conventional wafer processing involving both oxidation and annealing treatments. The results were interpreted within the framework of a developed model that takes into account migration of alkali ions in the presence of an electric field. A thermodynamic approach to alkali metal oxidation was used to explain the similarity of the results in oxygen and argon ambients. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.255.6.125 Downloaded on 2015-03-15 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.255.6.125 Downloaded on 2015-03-15 to IP
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