‌1. Basic purity requirements

≥99.999% (level 5N)‌

The basic purity must meet the national standard for high-purity gases (GB/T 387-2017), and the methane volume fraction is ≥99.999%.

Ultra-high purity (≥99.9995%)‌

It is used in cutting-edge fields such as semiconductor photoresist cleaning and amorphous silicon deposition, and trace impurities need to be further reduced.

‌2. Key impurity limits‌

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Note: Some high-end scenarios (such as semiconductor deposition) require metal ions (Fe, Na, etc.) to be ≤1 ppb, and particulate matter (≥0.1μm) to be ≤0.1/mL, and they need to be verified by ion chromatography and laser particle counter.

‌3. Relevance of application scenarios and indicators‌

Semiconductor manufacturing

Chemical vapor deposition (CVD): used to grow amorphous silicon thin films. Inadequate purity will lead to attenuation of transistor performance. It is necessary to control ethane ≤1 ppm and moisture ≤1 ppm.

Plasma etching: Participate in the patterning of silicon wafers, metal ions exceeding the standard will cause circuit short circuit.

Photovoltaic and sensors

The deposition of amorphous silicon layer of solar cells and excessive nitrogen/oxygen content of impurities will reduce the photoelectric conversion efficiency.

Calibration gas

When used as the reference gas for calibration of the instrument, the total impurities must be ≤10 ppm to ensure data reliability.

‌4. Packaging and storage and transportation specifications‌

Packaging: 40L special steel cylinder is filled with passivation treatment for inner wall to prevent impurities from precipitating.

Storage and transportation: Store in a cool and ventilated place away from light, with a temperature of ≤30℃ to avoid contact with oxidant.

‌5. Testing standards basis‌

Purity and impurities‌: Perform GB/T 387-2017 "High Purity Methane".

Trace analysis: Refer to SEMI standards (such as ICP-MS for metal ion detection).

The purity of electronic grade methane is directly related to impurity control, and the yield of terminal products is especially in advanced processes below 28nm, which must strictly meet the 99.9995% grade index.