Purity requirements and preparation technology of chip manufacturing gases

Technical description on chip manufacturing gas purity requirements and preparation technology

In the field of chip manufacturing, gas purity is a core factor that determines product quality and performance. From key processes such as lithography and etching to thin film deposition, trace impurities in the gas may cause chain reactions, leading to deviations in chip performance or even scrapping. The following specifications are given for gas purity requirements, preparation technology and quality assurance measures:

1. Core requirements for gas purity

1. common gas standard：
   • The purity of bulk gases such as nitrogen, hydrogen, oxygen, argon, and helium needs to reach more than 99.999999%(9N), and the content of impurities such as oxygen, water, and total hydrocarbons needs to be controlled within 1 ppb (one part per billion).
   • Special processes (such as processes below 14 nm) require the concentration of individual impurities to be less than 0.1ppb (i.e. 100 ppt), which is equivalent to the difficulty of finding a grain of salt in a standard football field.
2. Electronic special gas specification：
   • The purity of special gases such as doping gases (such as B2H6, PH3), etching gases (such as CF4, NF3), and deposition gases (such as SiH4, WF6) must reach 99.999%(5N) or more.
   • High-end processes (such as EUV lithography) require that the purity of the gas be increased to 99.9999%(6N), and the impurity concentration needs to be controlled at the ppt level (one part per trillion).

2. Impact and control of impurities

1. Key impurity types：
   • Metal impurities (such as Fe, Cu): Will change the electrical characteristics of semiconductors, resulting in increased leakage current.
   • Non-metallic impurities (such as O2, H2O): may cause oxidation reactions and destroy the uniformity of thin film deposition.
   • Particulate pollutants (>0.1μm): may cause short circuits or open circuits, directly affecting chip yield.
2. Purity assurance measures：
   • Adopt a multi-stage purification system to deeply remove impurities through adsorption, catalysis, air suction and other processes.
   • Equipped with online monitoring equipment to detect pressure, flow, dew point and particulate matter concentration in real time, and the data collection frequency is ≥1 time/second.

3. Core technology for gas preparation

1. Raw material purification process：
   • Adsorption method: Use molecular sieve, activated carbon and other adsorbents to remove impurities such as oxygen, water, and carbon monoxide, with a removal depth of 0.01ppbv.
   • Catalytic method: Catalyze the reaction of methane and oxygen at high temperature to produce carbon dioxide and water to achieve deep purification of nitrogen.
   • Glowing method: alloy materials are used to absorb impurities at high temperatures, mainly used for argon and helium purification and hydrogen recovery.
2. Precision synthesis technology：
   • For special gases such as silane (SiH4) and ammonia (NH3), the reaction conditions need to be accurately controlled through a chemical vapor deposition (CVD) process.
   • The accuracy of mixing gas needs to reach ppm (parts per million) or even ppb (parts per billion), just like the accuracy of mixing a drop of pigment in a swimming pool.

4. System integration and quality control

1. Gas supply system design：
   • It adopts a full-process independently controllable special gas system, covering gas sources, purification devices, pipeline networks and leak detection components.
   • The pipe is made of 316L stainless steel, the inner wall roughness is ≤0.4μm, and the weld is subjected to electrolytic polishing.
2. quality inspection system：
   • Regularly conduct high-precision tests such as gas chromatography and ICP-MS (Inductively Coupled Plasma Mass Spectrometry) to ensure that the impurity content meets the standard.
   • Implement annual pipeline pressure test and leak detection. When the leak rate exceeds 5%, pipe network maintenance is required.

V. Technological innovation trends

1. New purification technology：
   • Develop advanced processes such as membrane separation and cryogenic rectification to increase gas recovery rates to more than 95%.
   • Develop an intelligent purification system to automatically adjust the adsorbent regeneration cycle through AI algorithms and reduce energy consumption by 20%-30%.
2. Green preparation direction：
   • Promote closed-loop gas supply systems to realize the recycling of special gas and reduce emissions by more than 30%.
   • Use clean energy such as hydrogen energy to drive purification equipment to reduce carbon emission intensity.

It is recommended that chip manufacturing companies establish a gas quality traceability system and implement full life cycle management for each batch of gas. For continuous operation systems, an intelligent monitoring platform can be configured to collect purity, pressure, flow and other parameters in real time, predict equipment status through data analysis, and achieve preventive maintenance. 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 stable operation of the system.