Dose

Notes

The dose versus throughput versus defectivity trade is the central economic tension in EUV patterning.

Overview

Dose in lithography is the amount of exposure energy delivered to each unit area of photoresist, usually given in millijoules per square centimetre (mJ/cm2). It is one of the two main settings of an exposure, alongside focus, and the dose needed to print a feature at its target size depends mainly on the resist's sensitivity. In EUV lithography the choice of dose is a direct trade-off between pattern quality and how many wafers a scanner can expose per hour.

How it works

During an exposure, the scanner's light source fires pulses while the mask and wafer move, and the scanner controls the energy each part of the field receives. A sensitive resist needs less dose; a less sensitive one needs more. Engineers find the dose and focus that print a feature at its target size with acceptable margins, often by exposing a matrix of different settings on a test wafer. Scanners can also vary dose slightly across the exposure field and across the wafer, using measured critical dimension data, to even out systematic size variations.

At EUV wavelengths each photon carries about 14 times the energy of a 193 nm photon, so the same dose delivers far fewer photons. With so few photons per small area, random variation in how many arrive, known as photon shot noise, becomes significant. It shows up as rough line edges and as stochastic defects such as missing or merged contact holes and broken lines. Raising the dose adds photons and reduces these effects.

The cost is time. More dose per field means slower scanning for a given source power, so throughput falls. Chipmakers originally hoped to run EUV resists at about 20 mJ/cm2 but, according to industry reports, used around 40 mJ/cm2 and above for 7 nm. Resist designers describe the tension as a triangle between resolution, line roughness and sensitivity: improving one usually costs another.

Examples

• Exposing a test wafer with a matrix of dose and focus settings to find the best process window for a new layer.
• A scanner applying a dose map across the wafer, fed by CD measurements, to correct a systematic centre-to-edge size difference.
• An EUV contact layer run at a higher dose to cut the rate of missing and merged contacts, accepting fewer wafers per hour.
• A resist supplier offering a more sensitive EUV resist so that the same pattern prints at a lower dose and higher throughput.

Why it matters

Dose sets both yield, through feature size control and stochastic defect rates, and cost, through scanner throughput on the most expensive tools in the fab. Lithography process engineers, EUV specialists, scanner applications engineers and resist chemists work with it, and process control engineers use dose corrections to keep critical dimensions on target.

In the chip lifecycle, dose is chosen during process development together with the resist, refined during the ramp to balance defects against throughput, and then adjusted continuously in production to hold dimensions on target.

It matters most to: Computational Lithography Engineer, EUV Lithography Engineer, Lithography Applications Engineer, Scanner, Lithography Process Engineer, Process Control Engineer

Common confusions

Not the same as implant dose

In ion implantation, dose means the number of implanted ions per square centimetre. It shares the word but measures something different from exposure energy in lithography.

Not the same as source power

Source power is the light the scanner's source produces, in watts. Dose is the energy that reaches each area of resist; more source power lets the scanner deliver the same dose faster.

Not the same as radiation dose

In health and safety, dose means radiation absorbed by the body. Lithography dose is purely a process setting for the resist.

Sources

1. Finding, Predicting EUV Stochastic Defects (Mark LaPedus, 17 June 2021) (opens in a new tab), Semiconductor Engineering, 2026-10-22
2. Looming Issues And Tradeoffs For EUV (Mark LaPedus, 25 September 2017) (opens in a new tab), Semiconductor Engineering, 2026-10-22
3. Dose Mapper: Advanced System for Correction of Critical Dimension (CD) Variations in Deep Sub Micron Technologies (Deepak Sharma and others, Freescale Semiconductor, 16 July 2012) (opens in a new tab), Design And Reuse, 2026-10-22

Related terms

• WPH
• Source power
• Stochastic defect

Where it appears on the Hub

Used on 24 pages of the Hub. In each group, the pages that mention it most come first.