Application of nitrogen in semiconductor production

Nitrogen plays a vital role in semiconductor production. Its application runs through many core aspects such as wafer manufacturing and packaging testing. The specific functions are as follows:

1. Core protection role: isolate pollution and ensure purity

1. Prevent oxidation and pollution
   As an inert gas, nitrogen is chemically stable and hardly reacts with semiconductor materials such as silicon. During wafer storage, transportation and processing, nitrogen is filled into equipment or sealed containers to form an oxygen-free environment, effectively isolating impurities such as oxygen and water vapor in the air and preventing material oxidation or chemical contamination. For example:
   • Silicon single crystal growth: The oxygen-free environment created by nitrogen can reduce impurity interference and ensure the stable growth of silicon crystals. The purity of the final silicon wafer can reach 99.99999999%.
   • photoresist protective: The photosensitive components in photoresist easily react with oxygen and moisture to cause deterioration. Nitrogen provides an inert environment during photoresist synthesis and storage, extends shelf life and ensures lithography accuracy.
2. Equipment purging and purification
   In chemical vapor deposition (CVD), etching and other processes, reactive gases or by-products will remain inside the equipment. Nitrogen is purged to thoroughly remove residues, avoid cross-contamination, and ensure the quality consistency of each batch of products. For example:
   • CVD equipment maintenance: Nitrogen purging removes unreacted gases and reaction by-products and prevents pollution to subsequent processes.

2. Process control: Optimize the reaction environment and improve performance

1. Precise control of temperature and pressure
   Nitrogen maintains the stability of the reaction environment by adjusting the flow rate and pressure in high-temperature processes (such as annealing and thin film growth). For example:
   • Rapid Thermal Annealing (RTA): Nitrogen serves as a carrier gas to help achieve rapid temperature rise and fall and optimize semiconductor electrical properties.
   • gan growth: Nitrogen not only serves as a protective gas, but also participates in the reaction. By adjusting the concentration, the proportion of crystal components is accurately controlled to ensure the uniformity of film growth.
2. Optimization of etching and deposition processes
   • plasma etching: Nitrogen is used as an etching gas or auxiliary gas to stabilize the plasma state and form an accurate etching profile to avoid excessive removal or insufficient material.
   • CVD/PVD thin film deposition: Nitrogen serves as a carrier gas or reactive gas to promote chemical reactions and form high-quality insulating layers (such as silicon nitride) or conductive layers to improve device performance.

3. Packaging testing: Extend life and ensure reliability

1. Packaging process protection
   Nitrogen prevents the intrusion of oxygen and water vapor in the packaging process, reduces oxidation risks, and protects packaging materials and chips. For example:
   • lead-free soldering: Nitrogen reduces oxidation, ensures solder joint quality and improves reliability.
   • wafer thinning: The exposed area of the thinned chip surface increases, and it is necessary to operate in a nitrogen environment to prevent moisture and oxygen erosion.
2. test environment simulation
   Nitrogen gas simulates the actual use environment during the test process to accurately evaluate semiconductor performance. For example:
   • Bonding process: Nitrogen creates an oxygen-free dry environment to prevent metal wire oxidation and solder joint welding, and ensure electrical conduction reliability.

4. Economic and environmental advantages

1. On-site nitrogen production reduces costs
   Semiconductor factories are often equipped with nitrogen generators to produce nitrogen on-site through pressure swing adsorption (PSA) or cryogenic separation technology, reducing liquid nitrogen storage and transportation costs while reducing carbon emissions. For example:
   • PSA nitrogen generators: Air is used as raw material, and the energy consumption is only the electricity consumed by the air compressor. The operating cost is low and the efficiency is high.
2. High purity supply guarantee
   The nitrogen generator can produce nitrogen with a purity of more than 99.999%, meeting the extremely high requirements of the semiconductor industry for gas purity, preventing product pollution and oxidation, and improving the yield.