Compressed air plays multiple key roles in the single crystal production process, as reflected in the following core links:
1. Crystal growth environment control
- atmosphere protection: In the single crystal furnace, compressed air (or purified compressed air) is used to maintain a slight positive pressure in the furnace to prevent external impurities from entering. Some processes need to be mixed with inert gas (such as argon) to form a mixed gas environment, compressed air as the basic carrier gas to participate in the ratio control.
- temperature uniformity adjustment through the design of compressed air nozzle, the gas flow path in the furnace is optimized to assist in the temperature gradient control of the crystal growth interface.
2. Crystal processing and molding
- cooling and cleaning:
- in the multi-line cutting process, the compressed air injection system can efficiently remove silicon chips, while cooling the cutting line to improve cutting efficiency.
- During the grinding and polishing process, compressed air drives the rotating table and purges the polishing liquid to prevent residue from contaminating the surface.
- Fixture drive pneumatic clamps use compressed air to achieve rapid opening and closing, accurately fix the crystal position, and avoid mechanical stress damage.
3. Surface treatment and detection
- particle Removal after cleaning, high-pressure compressed air (up to 6bar or more) purges the crystal surface to remove nano-scale particles and meet the requirements of semiconductor-grade cleanliness.
- Detection equipment protection:
- in the optical inspection equipment, compressed air continuously purges the surface of the lens to prevent silicon powder deposition from affecting the inspection accuracy.
- Precision instruments such as X-ray diffractometers require compressed air to isolate external environmental vibrations.
4. Automated transmission system
- non-contact handling: In the crystal orientation and fragmentation links, compressed air suspension transmission technology (such as air bearings) can avoid cracks caused by direct contact and improve the yield.
- Beat control pneumatic valves and cylinders drive the rapid flow of wafers between cleaning, testing and packaging processes to achieve a transmission efficiency of 3-5 wafers per minute.
5. Special process support
- doping control in the ion implantation process, compressed air is used as a neutral gas to participate in the generation of plasma and assist in adjusting the doping uniformity.
- Emergency protection: In case of sudden power failure, the compressed air reserve system can maintain the gas flow in the furnace and prevent the crystal from cracking due to sudden temperature change.
Quality Control Requirements
- cleanliness grade: Compressed air contacting the crystal shall meet ISO 8573-1:2010 Class 1 standard (oil content <0.01 mg/m & sup3;, particulate matter <0.1 μm).
- Pressure stability: The pressure fluctuation of key process points (such as polishing) should be controlled within ± 0.02bar to avoid scratches on the crystal surface.
Innovative application trends
- energy saving optimization: The waste heat recovery system is used to preheat the compressed air cooling heat energy for the crystal cleaning liquid, and the energy utilization rate is increased by 15-20%.
- intelligent monitoring: Deploy compressed air leak detection systems (such as ultrasonic sensors) to monitor pipeline leaks in real time to prevent process abnormalities caused by pressure drops.
Compressed air systems have become an indispensable infrastructure in the single crystal production process, and their performance directly affects crystal quality, production efficiency and equipment life. With the popularization of 12-inch silicon wafer technology, the application of compressed air in the field of ultra-precision machining will be further deepened.
