Question

What are some advantages and disadvantages of thermal oxidation?

Answer 1

Growth of silicon dioxide is performed using thermal oxidation, either in a dry or a wet ambient. For the highest quality oxides, such as gate oxides, dry oxidation is preferred. Advantages are a slow oxidation rate, good control of the oxide thickness in thin oxides and high values of breakdown field. For thicker oxides, such as a field oxide in CMOS technology, wet oxidation is preferred. The main advantage is a fast oxidation rate, so that a thick oxide (around 0.5 micron) can be produced in a reasonable period of time (around an hour). The main disadvantage of oxidation is that a high temperature is required of typically 900C or above. For applications requiring a silicon dioxide layer produced at a lower temperature, plasma enhanced chemical vapour deposition can be used.

and also... some more Advantages and disadvantages

Advantages

• No erosion problems from the heat exchanger or
•       poisoning from the catalyst via metals or halogens.
• The gas stream is homogenised as it passes through the bed.
• Very thorough energy recuperation: 85 – 95 %
• Relatively low operating costs
• Autothermic operation with low VOC concentrations.
• Very low residue concentrations for VOC, NOx and CO

Disadvantages

• High investment costs
• Ceramic beds may be blocked by dust and condensed particles.
• In discontinuous operation, the bed must be re-heated every time, using extra fuel.
• Large size and weight
• A lot of maintenance and moving parts