Why Semiconductor Giant Expands Use of High-purity Fluorine (F2 Mix)?

According to SK Hynix's 2024 Sustainability Report recently released, Hynix will replace the nitrogen trifluoride gas used in semiconductor cleaning processes with more environmentally friendly low global warming potential (GWP) gases. It is reported that these processes use high-purity fluorine gas mixture (F2 Mix).

In the etching process of semiconductor production, structures are etched into the semiconductor. This step takes place in a so-called etcher. The etched material also deposits on the walls of the etching tool, so a separate process is required to clean the tool. In most cases, it is cleaned with NF3, but there are etchers on the market that use a high-purity F2/N2 gas mixture.

These gas mixtures remove SiO2 and Si3N4 compounds in an environmentally friendly manner and can replace NF3 as a cleaning gas. In addition, the GWP (Global Warming Potential) of the F2/N2 mixture is zero compared to NF3's 17900. The F2/N2 gas mixture can also replace other cleaning gases such as CF4 or C2F6.

SOLVAY has developed and patented different fluorine gas mixtures. As an environmentally friendly gas for CVD cleaning processes, Solvaclean® uses much less gas per cycle and is therefore more efficient, despite having a similar cleaning rate compared to alternatives. If F2 is released into the environment, it immediately decomposes into HF. HF is absorbed by moisture and subsequently washed away by rain. Nothing is left in the atmosphere. Solvaclean® products have a zero GWP (Global Warming Potential).

It is reported that chip manufacturers such as Hynix and Samsung are seeking to expand the application of high-purity fluorine mixed gas (F2 Mix).

Another increasingly used gas is hydrogen fluoride (HF), which is used in cryogenic etching equipment. HF has a GWP of 1 or less, much lower than the fluorocarbon gases used in the past for NAND channel hole etching. The fluorocarbon family gases carbon tetrafluoride (CF4) and octafluorocyclobutane (C4F8) have GWPs of 6030 and 9540, respectively.

The above-mentioned shift in gas usage is also expected to have an impact on the performance of related electronic specialty gas companies.