A study of buried silicon nitride layers formed by nitrogen implantation with a stationary beam

A buried silicon nitride layer of 330 nm thickness with a single crystal residual silicon layer of 220 nm on it was produced by the implantation of 150 keV N⁺ ions into silicon with subsequent annealing at 1200°C for 2 to 10 h. The implantation was performed at a dose of 1.2 × 10¹⁸ cm^-2 with a stationary beam and wafer scanning instead of beam scanning. The buried nitride layer and the top residual silicon layer were then characterized by infrared transmission, electrical measurements, ellipsometry and scanning electron microscopy in conjunction with angle lapping and chemical etching. The resistivity of this buried nitride layer is about 5 × 10⁹ Ω · cm and the breakdown electric field strength is greater than 3 MV/cm. Both the upper and lower silicon-silicon nitride interfaces are very abrupt with interface roughness of no greater than about 20 nm. These results show that the material quality of buried nitride samples prepared using stationary beams is largely comparable to that of samples prepared using beam scanning.