ASML Twinscan Lithography System

ASML TWINSCAN is the dual-stage lithography scanner platform that has shipped nearly every leading-edge DUV and EUV exposure tool from ASML since 2000, and its defining innovation is running wafer exposure and wafer measurement on two separate, independently moving stages inside the same machine at the same time. While one wafer sits under the projection lens being exposed, the next wafer already sits on the second stage having its alignment marks, height map, and tilt measured — so by the time the first wafer finishes and the stages swap positions, the incoming wafer is already fully characterized and ready to expose with zero measurement dead time. Every modern ASML scanner family — the NXT (ArF immersion), the NXE (EUV), and the newest EXE (High-NA EUV) — is built on this same TWINSCAN dual-stage architecture, which is why the name appears across generations spanning three different light sources and two different numerical apertures.

Wafer A loaded onto Stage 1
Wafer B loaded onto Stage 2 simultaneously
Parallel dual-stage operationBoth stages active at once, no idle time
Stage 1: exposure
Under projection lens, reticle scanned in sync
Stage 2: measurement
Alignment marks, wafer height map, tilt
↻ stage swap
Stages swap positions
Measured wafer moves to exposure, exposed wafer unloads
Next exposure starts immediately
No measurement wait — throughput stays high

The throughput gain from dual-stage operation is the entire commercial reason the architecture exists, since a leading-edge fab's cost per exposed layer is dominated by how many wafers per hour a single scanner can push through. A single-stage scanner must measure, then expose, then unload, one wafer at a time in strict sequence, with the lens sitting idle during every measurement step; TWINSCAN overlaps those two phases across two wafers so the expensive projection optics are almost never idle, which is what lets a single tool exceed 275 wafers per hour on mature NXT models even though each wafer still needs the same measurement steps as before. This matters more as node generations add more alignment marks and a finer height map per wafer to hold tighter overlay budgets — on a single-stage machine, every added measurement step would subtract directly from exposure throughput, while on TWINSCAN it only has to fit inside the other stage's exposure time.

TWINSCAN — Dual-Stage Timeline vs. Single-Stage overlapping measurement and exposure removes idle lens time Single-stage scanner (one wafer at a time) Measure W1 Expose W1 Measure W2 Expose W2 lens idle during measurement TWINSCAN dual-stage (two wafers overlapped) Stage 1: Expose W1 Stage 2: Measure W2 (parallel) Stage 1: Measure W3 (parallel) Stage 2: Expose W2 lens never idle same measurement steps, same lens — the difference is only scheduling across two stages NXT (ArF immersion), NXE (EUV), and EXE (High-NA EUV) all use this same dual-stage platform

ASML's TWINSCAN naming spans the full modern product line — NXT:2000i-class and newer for immersion ArF, NXE:3600D and successors for EUV, and EXE:5000/5200 for High-NA EUV — so a fab engineer calling a tool "a TWINSCAN" is naming the stage architecture, not any one light source or numerical aperture; the lithography scanner, dual-stage scanner, ArF immersion lithography system, extreme-ultraviolet lithography system, and High-NA EUV lithography system entries each describe a specific exposure technology that, in ASML's current lineup, is delivered on top of this same dual-stage TWINSCAN chassis.

Take ASML TWINSCAN lithography system further

Ask the copilot about this term, or have our engineers assess it against your process.

Ask CFSGPT about this → Request a technical assessment → Open the CFS app