Characterisation of pyramid formation arising from the TMAH etching of silicon

An investigation on the influence of etchant concentration, ambient temperature and wafer thermal history on the formation of pyramids arising from the TMAH etching of silicon has been carried out. The number and size of the pyramids were used as parameters for the investigation. From the results obtained from this study, we are able to explain the influence of the TMAH concentration and ambient temperature on the changes occurring at the silicon surface satisfactorily using the pH theory. However, the results from the rapid thermal annealed, the as-received Czochralski wafers, and the float zone wafers seem to favour the defects theory. We suggest that in order to explain the etching mechanism of TMAH of silicon satisfactorily, a combination of the pH and the defects theories is necessary.