Meaning
Chemical process used in semiconductor manufacturing and wastewater treatment to break down organic contaminants and oxidize surface materials. In advanced silicon wafer cleaning, ozone oxidation provides a highly reactive environment that removes trace organic residues and forms a controlled, ultra-thin protective oxide layer. The reaction proceeds through the generation of active oxygen radicals in aqueous or gas phases.
This method operates without leaving chemical residues that require extensive rinsing.
Reaction Dynamics
Ozone molecules dissolved in deionized water decay rapidly into hydroxyl radicals, which possess a high oxidation potential. These radicals react with carbon-carbon double bonds in organic compounds, converting them into soluble oxygenated species that dissolve in the aqueous solution. At the same time, the dissolved ozone reacts directly with the silicon surface to grow a dense silicon-dioxide layer.
The rate of oxide growth decreases as the oxide thickness increases, limiting the total thickness to around one nanometer.
Equipment Configuration
Wet benches use ozone generators that employ corona discharge to convert pure oxygen into ozone gas, which is then mixed into the cleaning water using a gas-liquid contactor. The concentration of dissolved ozone must be monitored continuously using ultraviolet absorption sensors to maintain a stable process. Spray processors deliver the ozonated water directly to the wafer cassettes, ensuring that fresh, active solution is always in contact with the silicon.
This setup must be sealed to prevent the escape of toxic gas into the cleanroom.
Environmental Protocol
Industrial parks in China enforce strict regulations on the treatment of factory effluent and the emission of volatile organic compounds. Local environmental protection bureaus inspect the chemical storage and treatment systems of fabrication plants to ensure that ozone emissions remain below the national safety limits. Wet scrubbers and thermal destroyers are installed to convert any residual gas back into stable diatomic oxygen before it is vented.
These safety measures are required to maintain the factory operating license under the latest environmental laws.
