Temperature effect study of silicon-on-insulator structures prepared by high dose implantation of nitrogen

The temperature effect on the microstructure of the N+-ion implantation-induced Si3N4 buried layer was investigated. The underlying silicon nitride layers were formed in a Si (1 1 1) wafer after implantation of 50 keV nitrogen ions (fluence: 1 × 1017, 2 × 1017 and 5 × 1017 ions/cm2). It was observed that a continuous amorphous layer of about 200 nm thickness was formed in all implanted samples due to the irradiation damage. After 30 min annealing at 900 °C, poly-crystalline Si3N4 products were found by TEM examination in the specimen implanted with 5 × 1017 ions/cm2 dose. In the case of annealing at 1200 °C a continuous single-crystalline α-Si3N4 buried layer was formed indicating that the amorphous layer in the implanted samples could be transformed into three successive layers, which are amorphous SiO2, single-crystal α-Si3N4 and retained defects from surface to inner substrate, respectively.