HOYA's Near-Monopoly in EUV Mask Blanks: The Glass Purity Wall No Rival Has Crossed

When TSMC or Intel mass-produce chips at 2nm and below, the manufacturing flow inevitably passes through a HOYA product: the photomask blank. Outside the semiconductor industry HOYA is known as an eyeglass-lens company — so how did it end up in such a critical position? This article explains both the technology and the business structure.

What is a mask blank, and why is it essential to chipmaking?

Lithography is the process of using light to print circuit patterns onto a wafer. The template used for the circuit is the photomask. It is the equivalent of a camera's negative film: a single mask transfers the same pattern onto hundreds of chip sites across a wafer, over and over. Producing one generation of a leading-edge chip requires anywhere from several dozen to more than 100 different masks, one for each layer.

A mask blank is the unpatterned raw plate from which a photomask is made. It ships as a glass substrate coated with light-shielding film — or, for EUV, with a multilayer reflective film — and photomask makers such as Toppan, Dai Nippon Printing and Photronics then write the circuit pattern onto it with electron beams to complete the photomask. A single finished EUV photomask can cost tens of millions of yen or more.

The full photomask manufacturing flow is covered in how photomasks are made (in Japanese) (industry overview).

Why are EUV mask blanks so difficult?

EUV (extreme ultraviolet) is the leading-edge lithography technology that uses light with a wavelength of 13.5nm — roughly 1/14th of the conventional 193nm exposure light. Because this light is absorbed by air, the inside of the exposure tool is a vacuum; and rather than passing light through the mask, EUV reflects it. The mask therefore becomes reflective rather than transmissive.

An EUV mask blank must clear all of the following technical hurdles at once.

The unit "ppb/K" means that even if the temperature changes by one degree, the substrate's length changes by only one part in a billion. This is what keeps circuit placement accuracy intact even as the mask warms slightly during exposure. The substrate uses ultra-low-expansion glass made by Corning of the US or SCHOTT of Germany, on top of which the Mo/Si multilayer is deposited with extreme precision so that EUV light is reflected at high efficiency (HOYA Corporation) (Semiconductor Engineering).

What kind of company is HOYA? From optical glass to EUV materials

HOYA was founded in 1941 in Tokyo's Toshima ward by Umekichi Yamanaka as Hoya Glass, established to manufacture and sell optical glass. Starting from the glass-polishing technology behind eyeglass lenses, it spent more than 60 years extending its precision-glass expertise, and today operates two major segments.

• Health Care: eyeglass lenses (among the world's largest in plastic lenses), intraocular lenses, medical endoscopes
• Information Technology (IT): photomask blanks and HDD glass substrates

Health Care accounts for roughly 70% of revenue, while the IT segment carries high profit margins. Both mask blanks and HDD glass are high-barrier oligopoly markets, positioned at chokepoints of the semiconductor manufacturing supply chain (HOYA Corporation IR).

Why does HOYA also dominate HDD glass substrates?

HOYA's other, often-overlooked business in the semiconductor context is glass substrates for hard disk drives. Compared with conventional aluminum substrates, glass can be finished to a surface roughness below 1nm, allowing the magnetic head to fly closer to the disk surface and enabling higher-density recording. As demand for large-scale storage for AI training expands, high-density HDDs that pack more data onto each platter remain in solid demand, and HOYA has established itself as a leading supplier here as well (HOYA Corporation).

Why do competitors not emerge? The triple entry barrier

New entry into the EUV mask blank market is difficult because three walls stack on top of each other.

The first wall is the material itself. Low-thermal-expansion glass approaches zero expansion by doping pure silica (SiO₂) with titanium dioxide (TiO₂) in precisely controlled ratios. This composition control, and the ability to produce large, uniform glass, is know-how refined over decades of development.

The second wall is deposition precision. The Mo/Si multilayer requires stacking about 40 layers while controlling each layer's thickness to the 0.1nm level; the precision of the deposition tools, the factory's temperature and humidity control, and film-thickness uniformity across the whole substrate directly determine yield.

The third wall is customer qualification. For a foundry such as TSMC, Samsung or Intel to switch mask blank suppliers, it must re-verify yields, run long-term reliability tests and complete quality qualification — a process measured in years. Once adopted, a supplier is rarely displaced until a generation change.

Together, this triple wall of materials, deposition and qualification locks in a supply structure built around a small number of players, chiefly HOYA and AGC.

How is HOYA connected to Lasertec and ASML?

The supply chain behind leading-edge chip production links several companies beyond HOYA. HOYA ships the mask blank → a photomask maker (Toppan, DNP, Photronics and others) writes the circuit pattern with electron beams → Lasertec inspects the mask for defects with its specialized tools (in Japanese) → ASML's EUV lithography machine prints the pattern onto the wafer.

Each stage of this chain is concentrated in companies with near-monopoly global positions, and Japanese firms handle two of the steps: mask blanks and defect inspection. See also how ASML's EUV lithography machines work (in Japanese) (Lasertec IR).

How will High-NA EUV change the requirements for mask blanks?

Next-generation High-NA EUV — which raises the numerical aperture (the lens's light-gathering capability) from 0.33 to 0.55 — makes the requirements on mask blanks even stricter. Because the larger aperture halves the area that can be printed in a single exposure, more masks are needed to manufacture the same chip. At the same time, the structural changes aimed at effectively shorter wavelengths are expected to tighten the specifications for surface roughness and defect density even further. In practice, this makes new entry beyond the existing handful of suppliers harder still (ASML / media reports).

Details of the next-generation lithography tools are covered in how High-NA EUV works and why it matters (in Japanese).

Where does HOYA sit in Japan's semiconductor materials cluster?

HOYA is one of the companies that embody Japan's international strength in semiconductor materials. Alongside Tokyo Ohka Kogyo, JSR and Shin-Etsu Chemical in photoresist, Shin-Etsu and SUMCO in silicon wafers, Ajinomoto in ABF insulation film, and JX Metals in sputtering targets, HOYA holds a global position in the precision optical glass at the heart of lithography. All are upstream materials invisible in the final product — yet their irreplaceability, and the high cost of switching once adopted, are what sustain their long-term market positions.

Key takeaways

• Photomask blanks are the raw glass plates for the master templates (photomasks) used in chip lithography, and HOYA stands alongside AGC as a leading global supplier for EUV.
• EUV blanks face a triple set of ultra-precision requirements — thermal expansion within ±1 ppb/K, about 40 Mo/Si layers, surface roughness below 0.1nm RMS — that forms the entry barrier.
• HOYA is also a leading supplier of HDD glass substrates, underpinned by AI-era demand for high-capacity hard drives.
• The difficulty of entry is sustained by a triple wall: materials technology, deposition precision and customer qualification that takes years.
• The chain from HOYA's mask blanks to photomask makers to Lasertec inspection to ASML EUV lithography underpins the world's leading-edge chip production.