Oil content standard for compressed air for semiconductor applications

Semiconductor manufacturing is a benchmark for precision manufacturing, and its production environment requires the extreme cleanliness of compressed air. The following is a systematic explanation of the oil content control requirements for compressed air in the semiconductor industry from three dimensions: industry standards, process adaptability, and quality control systems:

1. Oil content control standards for the semiconductor industry

1. international standard
   • Compressed air used for semiconductor manufacturing must meet the first-level standard of ISO 8573-1 “Compressed Air Quality Class”, that is, the oil content is <0.01mg/m³. In actual production, the internal control standards of leading enterprises have become stricter, generally requiring oil content ≤0.003mg/m³, and some key processes (such as lithography and thin film deposition) even require <0.001mg/m³.
2. Differentiation requirements for process links
   

   process links	Oil content control standard (mg/m³)	Core control elements
   wafer cleaning	≤0.001	Prevent oil pollution from causing surface defects
   photoresist coating	≤0.001	Avoid lithography pattern distortion caused by oil
   plasma etching	≤0.003	Prevent oil pollution from polluting the reaction chamber
   thin film deposition	≤0.005	Avoid oil content affecting the adhesion of the film
   packaging and testing	≤0.01	Prevent poor pin contact caused by oil pollution

2. Technical path for oil content control

1. Source purification plan
   • oil-free air compressor: Adopt water-lubricated or oil-free design to eliminate lubricating oil pollution from the source.
   • multistage filtration system: Configure pre-filter (accuracy 1μm), precision filter (accuracy 0.01μm), and activated carbon filter (adsorbing oil vapor) to achieve gradient purification.
2. Process monitoring system
   • on-line monitoring device: Laser scattering method is used to detect oil content in real time, and the data is connected to the factory MES system.
   • Manual sampling and testing: Gas chromatographic analysis is performed monthly to detect total hydrocarbon content (THC) and specific oil components.
3. end-processing technology
   • catalytic oxidation unit: Decompose oil vapor in compressed air into CO ˇ and H ˇ O under the action of a catalyst.
   • membrane separation technology: Use the selective penetration of polymer membranes to further reduce the oil concentration.

3. Key nodes of quality control

1. system design specification
   • pipeline material: 316L stainless steel pipes are used, and the inner wall is electropolished (Ra≤0.4μm) to reduce oil contamination.
   • pipe routing: Adopt an annular pipe network design to avoid dead corners, and configure an automatic drain valve to prevent condensation from accumulating.
2. Operation and maintenance management standards
   • Filter element replacement cycle: Precision filters are replaced every 2000 hours, activated carbon filters are replaced every 4000 hours.
   • leak detection: Conduct pipeline pressure maintenance tests every month, and use a helium mass spectrometer leak detector to locate small leakage points.
   • emergency plan: Configure a backup filtration system and switch to bypass air supply during maintenance of the main system.
3. Personnel qualification requirements
   • Operators need to pass special training on the compressed air system to master the key points of oil control and emergency treatment procedures.
   • Carry out simulation drills regularly to improve the ability to respond quickly to oil pollution incidents.

4. Industry development trends

1. intelligent management and control
   • Integrate Internet of Things technology to realize functions such as filter life prediction, energy efficiency analysis, and abnormal warning.
   • Digital twin technology is used to build a virtual model of the compressed air system and optimize operating parameters.
2. Low-carbon upgrade
   • Promote oil-free air compressors to reduce lubricating oil consumption and waste oil treatment costs.
   • Using waste heat recovery technology, compression heat is used for process preheating, and system energy efficiency is improved by more than 30%.
3. modular design
   • Develop prefabricated purification units that integrate filtration, drying, and testing functions to shorten on-site construction cycles.
   • Adopt plug-and-play interface to improve system expansion flexibility.

Semiconductor manufacturing has entered the nanogram era of controlling the oil content of compressed air (1ng/m³=0.001mg/m³). Enterprises need to establish a full life cycle management system from design, selection, operation and maintenance to monitoring, and through technological innovation and refined management, ensure that the quality of compressed air meets the needs of advanced process. It is recommended to conduct a systematic audit every six months, dynamically adjust control standards in conjunction with process upgrades, and continuously consolidate the foundation of clean production.