MICROSTRUCTURE OF CZOCHRALSKI-GROWN SI-TASI2 EUTECTIC COMPOSITES

The effects of forced convection, orientation of the Si matrix and a 1300°C anneal on the rod-like microstructure of a Si-TaSi2 semiconductor-metal eutectic grown by Czochralski crystal growth methods were studied. Analysis of the rod density, the distribution of the localized rod density and rod shape was performed using an automated, scanning electron microscope image analysis technique. Czochralski growth was found to lead to transverse wafers with localized rod density variations distributed in a spiral-like pattern analogous to the distribution of dopants found in transverse wafers of Czochralski-grown semiconductor crystals. The magnitude of the seed and crucible rotation rates affected the extent and position of rod density variations. At high rotation rates, portions of a wafer were found to have off-eutectic, Si-rich cellular structures. Finally, the eutectic microstructure was found to be stable at high temperatures. Although a 1300°C-24 h anneal did cause a reduction in the aspect ratio of the rod cross-section, no coarsening of the eutectic structure was observed. © 1990.