High Purity CO2 Procurement Alarm for Semiconductor Supercritical Cleaning Processes
Warning signs have emerged in the procurement of high purity carbon dioxide (CO2) used in advanced semiconductor processes, according to reports on the 26th.
The cause is a sharp decline in the volume of feedstock CO2 being generated, due to lower utilization rates at oil refining and petrochemical plants. Semiconductor manufacturers and suppliers each typically hold about two weeks of inventory, for a combined total of roughly one month's worth. Recently, however, the industry believes inventories have fallen below one month.
According to the industry, Samsung Electronics is understood to use about 1,800 to 2,000 tons of high purity CO2 per month, while SK Hynix uses around 600 to 700 tons per month.
Production disruptions at Samsung Electronics and SK Hynix have not yet materialized. However, inventory headroom continues to shrink, and for that reason the companies are intensifying their procurement efforts, a source familiar with the matter explained. Even by raising prices, securing additional volume is difficult.
A gas industry official said, "Without feedstock, we cannot supply as much as customers want," adding that "there is physically no way to ramp up production in the short term."
High purity CO2 is used in large quantities in supercritical (超臨界, supercritical) semiconductor cleaning processes. Supercritical refers to the physical state that appears when a substance exceeds its critical temperature and pressure. When liquid CO2 enters the supercritical state, the distinction between liquid and gas disappears and it takes on the properties of both states simultaneously. With a density comparable to a liquid, it readily dissolves residues and contaminants on the wafer, while its gas like nature lets it reach deep into fine patterns to remove debris. Advanced process semiconductors have narrow pattern spacing and large step heights, so they undergo the supercritical cleaning process.
CO2 feedstock is a byproduct of processes such as oil refining, petrochemicals, and hydrogen production. Instability in crude oil supply and demand stemming from the situation involving the United States, Iran, and the Middle East, and the resulting decline in domestic petrochemical plant utilization rates, are seen as having had a major impact on the CO2 feedstock shortage.
The price of liquefied CO2 is reported to have risen by around 20% compared with the start of the year. The industry views it as highly likely that the supply crunch will continue through the end of the year.
Major domestic high purity CO2 suppliers cited include Taekyung Chemical, Sundo Chemical, Dongkwang Chemical, and SK Air Plus. Taekyung Chemical is known as the leading player.
One semiconductor materials expert said, "After helium, anhydrous hydrofluoric acid, and PGMEA, now CO2 as well, Middle East crude oil risk is repeatedly spilling over into the semiconductor materials space," noting that "it means the materials supply chain is deeply intertwined with byproducts from oil refining and petrochemicals."