Ex situ silicon wafer cleaning by HF dipping has been studied in terms of cleaning efficiency. Silicon epitaxial layers were deposited in the MC-CVD (Multi-Chamber Chemical Vapor Deposition) reactor, which had a Load Lock Chamber. In situ cleaning was performed with an ECR (Electron Cyclotron Resonance) hydrogen plasma exposure. 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. HF dipping without water rinsing, followed by thermal heating up to 660°C provided the best results in terms of contamination. Rinsing seemed to help the surface natural oxide grow, but it improved the surface smoothness of the epitaxial layer. Blow-drying by nitrogen was important in reducing the interfacial oxygen concentration of the deposited epitaxial layer. Spin-drying turned out to be efficient in removing hydrocarbons or organic species. The ex situ cleaning played a major role in reducing the amounts of surface contaminants.
- Surface and interface states
- Transmission electron microscopy