Papers by Author: D. Kot

Abstract: Chromium-free preferential etching techniques in combination with light optical microscopy were compared with the non-destructive Laser Scattering Tomography (LST) for the evaluation of crystal defect densities in Czochralski substrates grown under different conditions. Dichromate containing etching solutions (original Secco etch and dilute Secco etch) were included into the study as reference. The chromium-free etching solutions with high etch rates comprised mixtures of nitric, hydrofluoric and acetic acid with water (JEITA 1, MEMC). Those with low etch rates consisted of mixtures of nitric and acetic or propanoic acid with hydrogen peroxide which form peracetic or perpropanoic acid (Organic Peracid Etches). OPE solutions provide improved discrimination of different types of defects and work also on highly doped substrates. As a general result, it turned out that the defect densities determined by the preferential etching solutions applied were significantly higher than those evaluated by LST. Relatively close to the LST defect densities are those determined by original Secco etch for larger etch pits.

Abstract: The results of highly sensitive FTIR investigation, ab initio calculations and rate equation modeling of the early stages of oxide precipitation are compared. The attachment of interstitial oxygen to VOn is energetically more favorable than the attachment to On for n  6. For higher n the energy gain is comparable. The point defect species which were detected by highly sensitive FTIR in high oxygen Czochralski silicon wafers are O1, O2, O3, and VO4. Rate equation modeling for I, V, On and VOn with n = (1..4) also yields O1, O2, O3 to appear with decreasing concentration and VO4 as that one of the VOn species which would appear in the highest concentration after RTA.