SEMICONDUCTOR PRINCIPLES

Lithography and pattern transfer

Here the two paths meet: a prepared wafer and a pattern that carries design intent. Light makes their connection.

Project a pattern, not a transistor.

A reticle carries the pattern. The optical system projects it onto light-sensitive photoresist on the wafer. Exposure changes the resist chemically; it does not instantly create a working device.

Reveal a temporary guide.

After the required processing and development, selected resist remains as a pattern. DUV systems use refractive lenses; EUV uses reflective masks and mirrors in high vacuum. Switch the optical view to see the distinction.

Let the next process do its work.

The developed resist guides processes such as etching. Subsequent steps transfer or build the desired structure, then remove temporary materials. A chip’s layer stack can use both EUV and DUV—not every layer needs EUV.

The optical diagrams explain the different principles, not a complete scanner ray trace. Mask reduction, optical distances and feature sizes are not drawn to scale.

Technical context

Design information becomes a wafer pattern through lithography. A reticle provides the pattern and optics project it onto light-sensitive resist. DUV uses lenses; EUV uses mirrors in vacuum. The exposed resist is only a temporary patterned guide for later processing, so one flash of light does not make a finished transistor.

A reticle carries a pattern; lithography projects and reduces that pattern onto a photoresist-coated wafer, where exposure changes the resist chemically.
DUV systems use refractive lenses. EUV systems use multilayer reflective mirrors because EUV is absorbed by ordinary materials, and the EUV optical path is kept in high vacuum.
EUV and DUV can both be used in a chip's layer stack; ASML states EUV is used for intricate layers while other layers use various DUV systems.

Sources

Lenses & Mirrors — Lithography Principles ↗ · ASML

EUV Lithography Systems ↗ · ASML