Atomic-order thermal nitridation of Si, Si_1-x Ge_x and Ge by NH₃

One of the main requirements for Si-based ultrasmall device is atomic-order control of process technology. Here, we show the concept of atomically controlled processing for group IV semiconductors based on atomic-order surface reaction control in Si-based CVD epitaxial growth. On the atomic-order surface nitridation of Si_1-xGe_x by NH₃, it is suggested that nitridation of Si atoms proceeds by transfer of N atoms from Ge atoms by heattreatment. In the case of epitaxial Ge film, the crystallinity change is not observed by NH₃ treatment and N atoms diffuse through nmorder thick Ge layer into Si (100) substrate and form Si nitride even at 500 °C. It is also suggested that N diffusion in Ge layer is suppressed by the formation of Si nitride. These results demonstrate the capability of CVD technology for atomically controlled nitridation of Si, Si_1-xGe^x and Ge for ultralarge scale integration.