Standard for compressed air in the semiconductor industry

The semiconductor industry has extremely strict quality requirements for compressed air and needs to meet a number of core standards to ensure product quality and production stability. The following is explained from three aspects: key parameters, system design and management specifications:

1. Core quality standards

1. Particulate matter control

• cleanliness level: It must meet Level 5 or higher in the ISO 14644-1 standard, that is, the number of particles ≥0.1 micron per cubic meter of air does not exceed 10000. Precision equipment such as lithography machines may require more stringent Class 100 clean room standards (≤3520 units/cubic meter).
• control significance: Particles may scratch the wafer or contaminate optical components, causing product defects.

2. humidity control

• dew point temperature: Generally, it is required to be below-40℃, and high-end processes may require below-70℃, corresponding to a water content of only tens of ppm.
• control significance: Prevent condensed water from causing equipment corrosion, circuit short circuits or product contamination.

3. Oil content control

• limit value: The total oil content needs to be less than 0.01mg/m³, which is close to oil-free.
• control significance: Avoid oil contamination of sensitive components or affecting the thin film deposition process.

4. Chemical pollutant control

• prohibited ingredients: Do not contain acidic substances, alkaline substances, ammonia, sulfides and other corrosive or polluting substances.
• control significance: Prevent chemical pollutants from causing wafer surface defects or equipment corrosion.

5. microbial control

• special requirements: In aseptic packaging and other aspects, the microbial concentration needs to be controlled through high-efficiency filtration and ultraviolet sterilization.
• control significance: Avoid the growth of microorganisms and affect product yield.

2. System design and equipment requirements

1. Compressed air treatment process

• typical configuration: Air compressor → buffer tank → aftercooler → multi-stage filter (dust removal and oil removal) → dryer (adsorption type or freezing type) → terminal filter → gas point.
• key equipment：
  • dryer: The adsorption dryer can achieve a dew point of-70℃, and the freezing dryer is suitable for general needs.
  • filter: A high-efficiency filter needs to be used, and the filtration efficiency of 0.01 micron particles reaches 99.999%.

2. Pipeline and Storage

• material requirements: The main pipe is made of 304L or 316L stainless steel, which needs to be pickled and passivated after welding, and the inner wall roughness is ≤0.8μm.
• layout specification: The slope of the pipeline is ≥1%, and a drainage valve is set every 30 meters to avoid the accumulation of condensate.

3. Pressure and flow stability

• pressure control: It needs to be stable within the equipment requirements (such as 0.5-0.7MPa), and the fluctuation range is ≤±0.05MPa.
• flow assurance: Dynamic adjustment is achieved through air storage tank capacity optimization (it is recommended to meet the 30-minute air consumption) and inverter compressor.

3. Operation management specifications

1. monitoring and measurement

• on-line monitoring: Install particle counters, dew point meters, and oil detectors to monitor air quality in real time.
• regular testing: Entrust a third-party agency to conduct all tests, including chemical pollutants and microorganisms, every quarter.

2. maintenance

• filter replacement: Replace the filter element every 3-6 months according to the differential pressure indicator.
• drier regenerant: Adsorption dryers need to replace molecular sieves regularly, and freezing dryers need to clean the condenser.
• pipeline cleaning: Carry out compressed air purging once a year to remove attachments on the inner wall of the pipeline.

3. Emergency Management

• standby equipment: Configure redundant air compressors and dryers to ensure that single points of failure do not affect production.
• Handling of abnormal pressure: When the pressure fluctuation exceeds the limit, the system automatically switches to the standby air source and triggers an alarm.

4. Industry application differences

V. Summary

The semiconductor industry compressed air standard is the cornerstone of quality control and needs to be achieved through precise system design, strict equipment selection and standardized operation management. Enterprises should establish a full-process quality control system from the outlet of the air compressor to the point of gas consumption, and formulate internal specifications in conjunction with ISO 8573 or GB/T 13277 standards to ensure that the quality of compressed air meets the strict requirements of semiconductor processes.