Si Epitaxial Growth on Atomic- Order Nitrided Si(100) Using an ECR Plasma Abstract authors: Masaki Mori, Junichi Murota, etc. TohoKu University, Japan Presented by Zhenwei Hou
Research Topic • Atomic-layer doping is necessary to develop future Si-based devices. • Si epitaxial growth on Atomic-order nitride Si (100) using an ECR (Electron Cyclotron Resonance) plasma without substrate heating.
Lowering Si epitaxial temperature is important to suppress plasma damage. ECR PECVD expiation Si without substrate heating. The molecular beam epitaxy: cleaning at 1200 C; Conventional plasma CVD is performed at 230 C; Remote PECVD works at 150 C. Advantage of Plasma Epitaxy without Substrate Heating
Atomic Order Nitridation of Si • p-type Si wafer with mirror-polished(100) surface is nitride by N plasma • N2 pressure: 2.6 Pa • MW power: 200 W • Initial surface N content on the Si substrate:1.5 ×1015 cm-2.
Si Epitaxial growth • After Si nitridation, epitaxial Si film is continuously deposited by Ar plasma • Ar pressure: 2.1 Pa • SiH4 pressure: 2.6 10-3 Pa • MW power: 800 W
The structure of film surface was evaluated by RHEED (Reflection High Energy Electron Diffraction). Film Texture
The Nitrogen Depth Profile • The N content profile was examined by the repetition of XPS (monochromated X-ray Photon Spectroscopy) and the wet etching. • The heavily N doping (0.5-1.0×1022 cm-2) exists in about 23-30 A region from the surface. • Total N content: 1.1×1015 cm-2
Nitrogen Atom Desorption • The N depth profile indicated a certain amount of N in the epitaxial Si layer. • The N atoms on the nitrided Si surface were desorbed by the H radical reaction. • The H radical can be generated by the SiH4 decomposition due to the Ar plasma.
Conclusion • The heavily doping of N atom is achieved without substrate heating by the repetition of the atomic-order nitridation of Si and the Si expitaxial growth using an ECR plasma. • The N desorption has to be considered in the continuous Si epitaxial growth.