The bottleneck of advanced process technology, do you think it's only the lithography machine?

Actually, there's also Photomask (photomask / mask plate).
If the lithography machine is a printing press, then the Photomask is the printing template / film, and the wafer is the paper being printed on.
The increase in semiconductor complexity brought by AI will directly impact Photomasks, and may even be further amplified.
In the past, the industry saw wafer usage increase by +10%, and mask demand by +10%.
In the AI era, it may turn into: wafer +10%, mask value +20%~40%.
Because the growth isn't just in the number of masks, but also includes:
mask layers
EUV layers
multi-patterning complexity
advanced packaging masks
RDL / interposer / HBM-related masks
inspection complexity
repair difficulty
mask write time
Photomasks are essentially no longer just "glass plates," but increasingly resemble "masters" in the semiconductor industry.
Mask area is much larger than chips, but the precision requirements are even higher. This is similar to EUV lenses: drawing an entire city map on an A4-sized area, with errors not exceeding a few nanometers.
A high-end mask with defects could cause thousands of wafers to be scrapped later.
Therefore, the core of the industry is defect control capability. Currently, high-end masks have entered the nanometer-level optical engineering stage. EUV masks, 3nm/2nm logic masks, HBM-related masks, and advanced packaging masks all far surpass the traditional DUV era.
Thus, high-end Photomasks are naturally industries with low throughput, slow expansion, and heavy process accumulation.
Compared to traditional DUV masks, which are transmissive with light passing directly through; EUV masks are multilayer reflective structures, containing Mo/Si multilayers, absorbers, pellicles, and ultra-low defect blanks.
Mask defects are infinitely replicable, so phase defects, CD errors, overlay errors, multilayer defects become extremely critical.
Hence, the importance of mask inspection is approaching that of the lithography machine itself, with very high technical thresholds.
Besides chip manufacturing, there are also advanced packaging masks: advanced packaging is essentially also a lithography industry.
CoWoS, Fan-Out, RDL, Interposer, EMIB, Hybrid Bonding—all fundamentally rely on Photomasks.
Because advanced packaging is no longer just "mounting chips," but reconstructing ultra-high-density micro-interconnect systems inside the package, responsible for data transfer, power distribution, clock synchronization, and high-frequency signal integrity.
The demand driven by AI is not just an increase in packaging quantity, but an explosion in the complexity inside each package.
In the past, 1~2 layer RDLs, now 5, 8, or even 10 layers or more.
Each additional RDL layer usually means a new mask process.
Thus, Photomask demand has shifted from "growing with wafer numbers" to "growing with system complexity."
Advanced packaging may be one of the fastest-growing subfields of Photomasks in the coming years.
Because AI packages are gradually turning into "micro motherboards."
A large portion of functions that originally belonged to PCBs and system boards are migrating into the package: HBM interconnects, high-frequency SerDes, Power Delivery, Chiplet Fabric.
Therefore, advanced packaging increasingly resembles a "post-process wafer fab."
This is also the fundamental reason why CoWoS, EMIB, Foveros, SoIC, Hybrid Bonding are becoming more asset-heavy and harder to expand.
They are no longer traditional packaging but system-level silicon interconnect manufacturing.
And as lithography machines become more expensive and scarce, each exposure becomes more costly.
Thus, wafer fabs will pay more attention to:
high-quality masks
inspection
repair
pellicles
overlay metrology
Meanwhile, EUV shortages will also drive multi-patterning.
Originally, a single-layer EUV might be forced to be replaced by multiple immersion DUV exposures, SADP, SAQP, which increases mask count.
Therefore, EUV scarcity doesn't necessarily suppress the Photomask industry; in many cases, it actually boosts demand for high-end DUV masks—especially in HBM, CoWoS, advanced packaging, RDL, and substrate processes that heavily rely on immersion DUV and packaging lithography.
This is also why the high-end Photomask industry increasingly resembles the HBM, CoWoS, and EUV ecosystems.
The real constraints on industry expansion are no longer just CapEx, but:
defect reduction
yield learning
inspection capabilities
process tuning
customer databases
long-cycle validation
process accumulation
Many parts are already beginning to resemble "industrialized craftsmanship."
Their bargaining power within the entire semiconductor ecosystem will grow stronger, and the market may not yet fully realize this.
Disclaimer: I hold assets mentioned in this article. The views are biased and do not constitute investment advice. DYOR.