Abstract
Copper decoration has been used to identify defects in n-type silicon wafers containing P-bands. This was done by depositing Cu(NO3)2 solution onto the wafer, followed by heat treatment. This technique has been shown to be fast and effective for decorating different kinds of defects in silicon. The defects are expanded due to precipitation of Cu during cooling and can be delineated by Secco etching. They will then be clearly visible even with the naked eye. In the present work, the wafer was analyzed under bright light. Secco etching was also directly applied on an as-cut wafer from the same position as the one with Cu decoration in order to investigate flow pattern defects (FPDs). It was found that the defect density was different in different defect areas, which indicated that this method could also be used to define defect regions. Carrier density imaging (CDI) was used to measure the minority carrier lifetime of another wafer from the same position after passivation of both surfaces with a-Si and low temperature annealing. A lifetime map can be obtained by CDI with a resolution comparable to microwave-photoconductancedecay (μ-PCD) but in a much shorter time. The defect boundary was shown in the lifetime map and the results were compared to those obtained by camera imaging and light microscopy.
