Inorganic acid and ammonia emission factors in semiconductor processes

Area of Science:

• Environmental Science
• Chemical Engineering
• Industrial Ecology

Background:

• Semiconductor manufacturing utilizes hazardous chemicals, necessitating the assessment of emissions from pollution control devices.
• Understanding emission factors is crucial for environmental compliance and process optimization in the semiconductor industry.

Purpose of the Study:

• To quantify emission factors for inorganic acids and ammonia from nine semiconductor facilities across five technological nodes (1.2 μm down to 12 nm) between 2020 and 2022.
• To analyze trends in these emission factors relative to manufacturing process advancement and scrubber operating conditions.

Main Methods:

• Emission factors were calculated as pollutant emissions per unit of chemical usage after pollution control.
• Data were collected from nine semiconductor manufacturing facilities representing diverse technological nodes.
• Statistical analysis was performed to identify trends and correlations.

Main Results:

• Emission factors for hydrochloric acid, sulfuric acid, hydrofluoric acid, and ammonia were determined to be 0.0017, 0.0002, 0.0017-0.013, and 0.002 kg/L, respectively.
• Acid emission factors, particularly for older 1.2 μm nodes, were found to be lower than previously reported literature values.
• A general decreasing trend in inorganic acid emissions was observed with process advancement, while ammonia emissions increased with higher ammonium ion concentrations in scrubber water.

Conclusions:

• Ammonia is the dominant emission species in semiconductor manufacturing, with its proportion increasing in more advanced processes.
• Emission factors for inorganic acids decrease with technological advancement, suggesting improved pollution control efficiency for these substances.
• Further research into controlling ammonia emissions is warranted given its increasing prevalence in advanced semiconductor fabrication.