The semiconductor industry has extremely high requirements for compressed air quality, mainly due to the stringent requirements for environmental cleanliness in the semiconductor manufacturing process. Compressed air is widely used in semiconductor manufacturing, such as wafer growth, chip cooling, lithography and patterning, packaging and testing, and its quality directly affects the performance and reliability of the product. The following are the specific requirements and basis for the quality of compressed air in the semiconductor industry:
cleanliness requirements of 1. compressed air
- particulate matter control
- standard: It is usually required that the concentration of particles less than 0.1 microns in compressed air does not exceed 3520/m3 (100-level clean room standard).
- Reason: Particulate matter may contaminate the wafer surface, resulting in short circuits or performance defects.
- Oil content limit
- standard: The total oil content should be controlled 0.01 mg/m & sup3; below(Some processes require 0.00ppm).
- Reason: Oil will contaminate semiconductor materials and affect their electrical performance and reliability.
- Humidity control
- standard: The dew point temperature shall reach -40 ℃ to -70 ℃ the corresponding water content is below tens of ppm.
- Reason: Moisture may cause condensation on the surface of the device or wafer, causing corrosion or oxidation reactions.
Application Scenarios of Compressed Air in 2. Semiconductor Manufacturing
- wafer Growth and Processing
- compressed air provides a high-temperature and high-pressure environment to accelerate wafer growth while ensuring surface cleanliness.
- Chip cooling and cleaning
- use 0-grade oil-free air to cool the chips to prevent overheating damage; compressed air purges the wafer surface to remove dust and impurities.
- Lithography and Patterning
- compressed air is used to accurately imprint wafer patterns to ensure lithography accuracy and high air quality requirements.
- Encapsulation and testing
- compressed air drives pneumatic control components to accelerate the packaging process and ensure environmental temperature and humidity control.
3. related standards and specifications
- international Standards:
- following the ISO 8573.1 standard, which classifies contaminants in compressed air into three categories: solid impurities, water and oil, the semiconductor industry generally requires the highest air quality ratings.
- Industry Practice:
- pressure control: The compressed air pressure needs to be stabilized at 0.8-0.85MPa to meet the equipment drive and process requirements.
- Monitoring and purification multi-stage filtration (coarse filtration, fine filtration, sterilization filter), drying device (adsorption or freezing dryer) and real-time monitoring equipment are adopted to ensure that the compressed air meets the standard.
4. Typical Cases and Impact
the oil content of compressed air in a semiconductor factory exceeded the standard (reaching 0.1 mg/m & sup3;), resulting in unstable electrical performance of a batch of chips, and the yield decreased by 15%. After upgrading the oil-free screw air compressor and adding activated carbon filter device, the oil content dropped to 0.005 mg/m & sup3;, the yield recovered to more than 98%.
Conclusion the semiconductor industry has extremely strict requirements on the quality of compressed air. High-precision filtration, drying and real-time monitoring are required to ensure the oil-free, water-free and dust-free characteristics of compressed air to ensure the stability of the production process and product reliability.
