Thermal oxidation is typically done to oxidize Silicon in air at high temperature (~1100 C). At such high temperature, oxygen reacts with Silicon to form Silicon Dioxide. As Silicon is oxidixing, Oxygen reaching the unoxidized Silicon layer is reducing and controlled by process of Diffusion. Hence, the rate of oxidation decreases with time.
Air may be replaced with other gases such as pure oxygen, mixture of oxygen with inert gases, or water vapor. Air flow can be controlled or the process can even run in stagnant mode (i.e. no air flow). Typically, the process is carried out at ambient pressure.
The above process can be carried out in IMSE Facility. IMSE offers Tube Furnace to accomplish the task safely. Click the link to start the training process.
Thin film metrology
Estimating oxidation peformance (oxidation rate, planar roughness, etc.) is critical to fabricate device at micron scale in repeated manner. IMSE offers number of instruments ( Ellipsometer, Profilometer, Optical Microscope, SEM) to help in the quantitative measurements.
- Optical microscope can measure the critical dimension width (for patterned thin films)
- Profilometer can measure the thin film height as long as step edge is available. The simplest solution may be to cover part of planar surface with kapton tape during metal deposition. Instrument may also be used to estimate roughness of etched films.
- Ellipsometry can measure the film thickness of selected materials when deposited on Silicon substrate. Unlike profilometer, no patterned region should exist in the area of measurement.