Importance of Humidity in Local Oxidation Processes. Field-enhanced oxidation of silicon or anodization of metals is highly dependent on environmental conditions. Humidity is of particular importance since the availability of water (in the air or adsorbed onto surfaces) will directly affect the rate of oxidation. We are exploring the effect of humidity control on local oxidation with scanning probes. We suspect that operating in a high humidity environment will allow higher speed oxidation. We are also investigating the effects of operating in a stable humidity environment and whether this affects oxidation repeatability.

Humidity Control Apparatus. We are using a bubbler fed with compressed air to adjust the humidity inside a commercial AFM chamber. A humidity sensor is placed inside the chamber near the tip. The compressed air pressure is adjusted to maintain a constant relative humidity inside the chamber, which can be varied from about 30% relative humidity up to almost 90% relative humidity and can be held fixed to within 0.5%. Here is a picture showing the setup for humidity control in the AFM chamber.