Physical and electrical investigation of silicide precipitates in EFG polycrystalline silicon intentionally contaminated with chromium

The results of a microstructure and deep-level transient spectrometry (DLTS) investigation of edge-defined film-fed growth (EFG) polysilicon ribbon intentionally chromium contaminated are presented. Chromium disilicide precipitates were identified in crystallographically degenerate areas of ribbon. An impurity energy level at 0.27 eV above the valence band edge is believed due to a chromium impurity concentration of ≈10¹³/cm³, while broad DLTS peaks centered at 0.30, 0.34, and 0.39 eV above the valence band edge may be due to crystalline defects. Cell fabrication reduced the electrically active chromium concentration to below the DLTS detection limit of 2×10¹¹/cm³. Evidence of denuded zones around the precipitates revealed by electron-beam-induced current (EBIC) examination indicates gettering may occur through the interaction of precipitates with the fabrication process