Post 8. Inversion Semiconductor (YC W25) - Company Note 01

A Challenger to ASML's Photolithography Dominance

I hope everyone has had a great start to the week.

Today, I took a midterm for Operations, Information, Data, & Decisions (OIDD) 3140, a business course dedicated to exploring the AI stack.

The AI stack is usually broken down into four layers: chips, the cloud, models, and applications. At the base of it all is the chip layer — the physical compute that everything else runs on. And even within chips, there are a few important steps: chip design, foundries, and photolithography.

Photolithography is basically the stamping process — it’s how you print circuit patterns onto a chip’s silicon wafers. It’s one of the most complex, expensive parts of the entire chip-making process, and it's been completely dominated by one company: ASML, a Dutch firm with a near-monopoly on extreme ultraviolet (EUV) lithography. The reason? Capex. These machines can cost over $150 million each, and building them requires a mind-blowing global supply chain and years of technical know-how.

ASML's EUV systems are so advanced that no one else has even come close — until now.

Today, I came across Inversion Semiconductor (YC W25). They’re trying to take on ASML by rethinking photolithography from the ground up — not just making it slightly better, but using particle accelerator physics to completely change how chips are made.

Instead of the traditional EUV approach (with mirrors, tin droplets, etc.), Inversion is using laser wakefield acceleration (LWFA) — a method that uses compact particle accelerators to generate incredibly powerful, tunable light sources. The idea is to build a system that can produce better chips way faster and without the multi-billion-dollar infrastructure that current tools require.

They claim it could be up to 15x faster than today’s tech — and if that’s true, it could totally change the game in semiconductor manufacturing. It will be an interesting story to follow.

Before ending this note, I would also like to wish my good friend Colin Gordon a happy birthday. You legend. Hope it’s a good one.

Hope everyone has a great evening.

Best,

Jack