Compressed air for semiconductor industry

Technical note on compressed air applications in the semiconductor industry

In the field of semiconductor manufacturing, compressed air is the core process medium, and its cleanliness, stability and reliability are directly related to product yield and production line efficiency. In the entire process from wafer manufacturing to packaging testing, compressed air plays an irreplaceable role in ensuring ultra-precision processing and achieving nanoscale process control by providing clean power sources, process media and environmental control support. The following explanation is given on its technical value and system specifications:

1. Core process application scenarios

1. Clean room environment maintenance：
   • By continuously supplying clean compressed air, a positive pressure environment in the clean room (usually 5-15Pa) is maintained to block the intrusion of external pollutants.
   • In an ISO 3 (Class 100) clean room, 15-20 complete air replacements are required per hour, and compressed air needs to account for 30%-40% of the air supply.
2. Precision equipment drive：
   • Provides clean power for pneumatic manipulators, vacuum cups and other actuators, and the repetitive positioning accuracy can reach ±0.005mm.
   • Around precision instruments such as lithography machines and wafer inspection equipment, a micro-environment system driven by compressed air can maintain local cleanliness up to ISO 1 (Level 10) and a vibration value of ≤0.5μm.
3. Special process media supply：
   • In chip manufacturing, compressed air-driven plasma cleaning equipment can remove sub-nanometer pollutants on the wafer surface.
   • In the processing of optical elements, compressed air is mixed with abrasive to form aerosol to achieve ultra-smooth surface processing, with surface roughness Ra≤0.2nm.

2. Compressed air quality requirements

1. cleanliness standard：
   • Must meet ISO 8573-1 Level 1 standards, including:
     • Particulate matter: Concentration of particles below 0.1μm ≤1000/m³
     • Oil content: ≤0.01mg/m³
     • Humidity: -70℃ pressure dew point (equivalent to-90℃ dew point under atmospheric pressure)
2. special technological requirements：
   • In the chemical vapor deposition (CVD) process, compressed air needs to be treated by activated carbon adsorbers to ensure that the total hydrocarbon content is ≤0.1ppm.
   • During the ion implantation process, a static removal device needs to be equipped to control the air ionization degree within ± 50V.

3. System configuration specifications

1. Multi-stage purification system：
   • Configure four-level purification devices with pre-filter (5μm), precision filter (0.01μm), chemical filter (activated carbon), and sterilization filter (0.001μm).
   • In the biopharmaceutical clean room, a sterilization filter (0.001μm) needs to be added, and the sterilization efficiency is ≥99.9999%.
2. intelligent monitoring platform：
   • Monitor 12 parameters such as compressed air pressure, flow rate, dew point, and oil content in real time, and the data collection frequency is ≥1 time/second.
   • Set a three-level alarm threshold, start switching of alternate air sources within 10 seconds after exceeding the limit, and trigger sound and light alarms and text messages.
3. Pipeline system design：
   • The main air supply pipe is made of 316L stainless steel seamless pipe, with inner wall roughness ≤0.4μm, and the weld is subjected to electrolytic polishing.
   • The terminal branch pipe is equipped with an automatic drain valve to automatically discharge condensate every 2 hours to avoid the growth of microorganisms.

4. Operation and maintenance standards

1. Daily inspection requirements：
   • Check the exhaust temperature, pressure and oil level of the air compressor every 2 hours, and record the pressure change curve of the air storage tank.
   • Test the pressure difference of the end filter every day and replace the filter element immediately when it exceeds the initial value by 50%.
2. Annual testing items：
   • Carry out full testing on compressed air, including total microbial count, endotoxin content, VOCs concentration and other indicators.
   • Verify the tripping pressure of the safety valve, replace it immediately if the error exceeds ±3%, and conduct a pipeline pressure test.

It is recommended that semiconductor companies establish a compressed air quality management system to implement full-process quality control from gas source equipment selection, pipeline construction acceptance to daily operation and maintenance. For continuous operation systems, an intelligent monitoring platform should be configured to achieve real-time monitoring and abnormal warning of key parameters such as pressure, flow, and purity to ensure that the clean room environment continues to be stable within the range of process requirements. At the same time, it is recommended to conduct pipe network leakage testing every quarter and entrust a third-party testing agency to issue a full quality report every year to ensure the continuous and efficient operation of the system.