We investigated low temperature out‐diffusion of Cu impurity from the bulk of p‐ and n‐type silicon wafers after contamination followed by diffusion of Cu into silicon during annealing. We show that Cu impurity in the bulk after low‐temperature out‐diffusion can be measured at the surface by total x‐ray fluorescence and graphite furnace atomic absorption spectroscopy 1010 atom/cm3. In addition, a benefit of low‐temperature annealing is the removal of Cu contamination from the bulk by surface cleaning. We also find that Cu contamination in the bulk of p‐type Si wafers out‐diffuses at room temperature after removing the surface oxide, but this does not happen in the case of n‐type Si material.

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Variation in the surface concentration of Fe, Ni, Cu and Zn on Si wafers due to treatment in NH4OH/H2O2/H2O solution is investigated. It is shown that adsorption and desorption of the metallic impurities occur simultaneously in the solution. The metal concentration on the wafer surface depends on the initial surface concentration, concentration in the solution, adsorption probability, desorption rate constant and the treatment time. The measured surface concentration is explained by taking into account the effects of these parameters. The variation in the desorption rate constant with the metal species, treatment temperature and the concentration in the solution is discussed.

A total reflection X-ray fluorescence (TRXRF) technique has been recently used to analyze metal contaminations on Si wafers. In this work, microdrop-contaminated Si wafers are used to make the calibration curves. Metal impurities in these wafers are shown to be condensed in a very small area near the center of the dropped area. To make the calibration curve, a relationship is derived between the intensity of the characteristic X-ray from metal impurities in the condensed area and that from the impurities uniformly distributed over the wafer surface. On the basis of this relationship, calibration curves for Fe, Ni, Cu and Zn are obtained.

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