Korea Zinc (010130) is strengthening its supply chain for ultra-high-purity sulfuric acid, a critical material for South Korea's semiconductor industry.
The company said on the 2nd that it recently completed an expansion of its No. 20 and No. 21 semiconductor sulfuric acid production lines at its Onsan smelter in Ulsan and has begun full operations. The expansion lifts Korea Zinc's semiconductor sulfuric acid capacity to 320,000 tons a year from 280,000 tons, an increase of about 14.3%.
The expansion was designed to get ahead of new production facilities coming online at major domestic chipmakers as they ramp up investment in artificial intelligence infrastructure. Korea Zinc has been expanding its semiconductor sulfuric acid capacity in stages to match customers' equipment investment schedules.
Semiconductor sulfuric acid is used in cleaning processes that remove organic residue and microscopic contaminants from wafer surfaces. As circuits shrink, tolerance for impurities falls sharply, making the purity and consistency of the acid a direct factor in chip yields and reliability. Unlike commodity products that can be shipped as soon as a production line is in place, suppliers must pass customers' quality approvals and process validation and demonstrate a track record of stable supply.
Korea Zinc recovers and refines sulfur dioxide (SO₂) generated during zinc and lead smelting through multiple stages to produce "six nines" (6N) grade ultra-high-purity semiconductor sulfuric acid, with purity of at least 99.9999%. Unlike the common method of sourcing sulfur externally to make sulfuric acid, using smelting byproducts as feedstock shields the company from cost pressures such as spikes in global sulfur prices.
Korea Zinc is the largest supplier of semiconductor sulfuric acid in South Korea, accounting for more than about 60% of domestic demand. About 95% of its output goes to major domestic chipmakers including Samsung Electronics and SK hynix, with exports also going to Japan and Singapore.
The company plans to raise semiconductor sulfuric acid capacity gradually to as much as 500,000 tons a year in line with domestic chipmakers' expansion schedules. It is also considering building a semiconductor sulfuric acid line with annual capacity of about 100,000 tons at an integrated smelter in Tennessee, which it is developing with a target of trial operations in 2029 and commercial production in 2030.
"Semiconductor sulfuric acid is a core material tied directly to chip yields and reliability, so what matters is not only production facilities but also ultra-high-purity refining technology built up over many years, quality control capabilities and a record of stable supply," a Korea Zinc official said. "We will expand domestic capacity in stages in line with customer demand and investment schedules, while building a supply base for semiconductor sulfuric acid in the U.S. and other global markets to establish ourselves as a key partner in the global chip materials supply chain."
