Removal Process of Surface Oxgen and Carbon Species for Surface Modification

초록

As device dimensions are reduced into the sub-micron regime in pursuit of higher integration density and better circuit performance, the surface modification has been a major issue in microelectronics technology and will be more critical in the future. Surface preparation techniques that avoid surface contamination and generate very clean wafer surfaces have become of critical importance. The focus of the research was on the removal of oxygen and carbon prior to epitaxial deposition, since other contaminants such as metals can be suppressed to negligible levels by careful wafer handling, and by the conventional RCA cleaning, etc. In-situ cleaning by ECR hydrogen plasma, especially when it was optimized, was effective in removing the natural oxide on the wafer surface. Removal of carbon from the surface proved to be easier than removal of oxygen. Reducing oxygen content seemed to be more important factor than reducing carbon content for obtaining the silicon homoepitaxial layer. The XTEM (Cross-sectional Transmission Electron Microscopy) was performed to investigate the structural qualities of the epitaxial layer and the epilayer/substrate interface. The SIMS (Secondary Ion mass Spectroscopy) was performed to investigate their interfacial carbon and oxygen concentrations. The possible reaction mechanisms of oxygen and carbon removal were discussed.