Semiconductor etching and ozone (O₃)
Q1：Does semiconductor etching itself generate ozone?
Strictly speaking, ozone is not an intended product of semiconductor etching. However, in modern fabs, dry etch and ashing processes inevitably generate ozone, particularly in plasma and exhaust regions when oxygen-containing gases are used.
Q2：Where is ozone mainly generated—in the chamber or in the exhaust?
Ozone is generated primarily in downstream and exhaust regions.
Inside the plasma zone, atomic oxygen (O•) dominates, while in cooler exhaust areas, recombination leads to ozone (O₃) formation.
Q3：Which etch-related processes are major ozone sources?
Major ozone-generating processes include:
O₂ plasma photoresist ashing
Oxygen-containing plasma etch processes
Multi-patterning etch flows following EUV lithography
Post-etch plasma chamber cleaning
Among these, ashing tools are often the largest ozone emitters in etch areas.
Q4：What are the impacts of ozone on etch tools and fabs?
Corrosion of vacuum pumps, valves, and seals
Accelerated aging of O-rings and polymers
Health hazards to operators
Cleanroom air quality degradation
Increased EHS compliance burden
Q5：Why is activated carbon not suitable for ozone removal?
Activated carbon is rapidly oxidized and consumed under high ozone concentrations, potentially generating particulates and safety risks.
In semiconductor fabs, ozone must be removed by catalytic decomposition, not adsorption.
Q6：What ozone removal solution is typically used for etch exhaust?
Catalysts are typically Mn–Cu oxide-based ozone decomposition catalysts (Carulite-type).
Q7：How do fabs meet ozone regulations in etch areas?
Tool-level catalytic ozone destruction
Redundant multi-stage systems
Continuous ozone monitoring
Compliance with EHS / SEMI S2 standards
Target level:
< 0.1 ppm in occupied areas
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