YC Chem

YC Chem has spent over two decades in one of semiconductor manufacturing's least visible corners: the wet chemicals that make photolithography actually work. Founded in 2001 and based in Seongju, Gyeongbuk — not exactly Korea's usual semiconductor hub — the company built its reputation on a string of firsts nobody outside the industry ever hears about: the world's first ArF and KrF photoresist rinse in 2004, the world's first specialty ArF-immersion rinse in 2015, and EUV pattern-collapse-prevention chemistry in 2016. It listed on KOSDAQ in 2022.

None of that sounds like a glass substrate company, and until recently it wasn't one. But the underlying skill — formulating photoresist, developer, and stripper chemistry precisely enough to survive the industry's most demanding lithography nodes — turned out to transfer directly to glass, which has its own, different set of chemistry problems.

YC Chem's core semiconductor product line covers photoresist, developer, stripper/etchant, rinse solutions, spin-on-carbon (SOC), CMP slurry, and thinner — the wet-chemical backbone of the photolithography process. A meaningful share of that goes into high-bandwidth memory production: the company supplies TSV (through-silicon-via) photoresist used in HBM manufacturing, with more than 70% of its revenue reportedly coming from SK hynix.

Glass introduces a chemistry problem that silicon doesn't have: glass's smooth surface doesn't naturally hold onto metal the way silicon does, which becomes a real yield risk once you're stacking multiple redistribution layers (RDL) of copper wiring on top of it. YC Chem's answer was to develop a full trio of glass-substrate-specific chemicals — photoresist, stripper, and developer — built on its twenty years of photoresist formulation experience, plus something new: a specialty polymer glass coating agent, developed as (by the company's account) the world's first of its kind, that improves adhesion between glass and copper and protects against cracking during the etching step.

YC Chem's most-cited claim, repeated by multiple securities analysts in 2025, is that it's the only supplier providing all three of the core glass-substrate chemicals — photoresist, stripper, and developer — into a single major domestic customer's production line at once. That's an unusual position: in most process-chemical categories, customers deliberately dual-source to avoid depending on one supplier. If the claim holds, it means YC Chem's glass revenue is tied unusually tightly to how fast that one customer's glass substrate line actually ramps — a concentrated bet, in either direction.

Beyond glass, the company is also trying to localize Korea's supply of EUV photoresist rinse, a category currently dominated by a German supplier with no domestic alternative. If YC Chem commercializes it, that would be the first domestic substitute in that specific chemical category — a smaller story than glass substrates, but one with its own clear catalyst if it lands.

YC Chem sits in stage 3, equipment & process technology, on the chemistry side rather than the hardware side — the same stage as PhilOptics (lasers) and Chemtronics (full wet process), but supplying the consumable chemicals those companies' tools actually use.

Equipment vendors get most of the headlines in glass substrates because a laser tool or a factory groundbreaking is easy to photograph. Consumable chemicals are less visible but recur every production cycle in a way capital equipment doesn't — once a customer qualifies a specific photoresist or stripper formulation for its line, switching suppliers means requalifying the entire process, which is slow and expensive. That switching cost is exactly why analysts have flagged YC Chem's chemistry as a potential earlier and steadier revenue stream than equipment sales, once glass substrate lines move from pilot to volume.

The company itself has been explicit that it sees silicon photonics, not just AI accelerator packaging, as a second demand driver for glass substrates — pointing to industry alliances like the one TSMC, ASE, and MediaTek formed around silicon photonics as evidence that glass's addressable market may be broader than the AI-chip story alone suggests.