Anisotropy of the Porous Layer Formation Rate in Silicon with Various Acceptor Concentrations

Abstract:

The orientation dependence of porous Si formation rate has been studied by local anodization of p-Si wafers with a boron concentration N_B = 3·10¹⁵ - 2·10¹⁹ cm^-3 at various currents with the help of a wagon wheel technique. It is demonstrated that the etch rate diagram is drastically transformed as the dopant concentration in p-Si is changed. The highest etch rate is observed in the <100> direction for heavily doped p⁺⁺-Si, whereas for p⁺-Si with N_B < 2·10¹⁸ cm^-3, <111> axis becomes the fastest direction. Further decrease in the doping level makes the anisotropy weaker, and at N_B <2·10¹⁶cm^-3, the anodization rate becomes nearly independent of the crystallographic orientation. For all the impurity concentrations in the substrate, the anisotropy is the strongest in the case of anodization at low currents and gradually decreases with increasing current density.

• Periodical: Solid State Phenomena (Volumes 205-206)
• Pages: 370-375
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.205-206.370
• Online since: October 2013
• Authors: Ekaterina V. Astrova, Yuliya A. Zharova
• Keywords: Anisotropy, Etching Rate, Porous Silicon

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