EUV Photodiode 13.5 nm Power & Dose Monitoring

Extreme ultraviolet (EUV) lithography lives or dies by the stability of its source. Every wafer exposure depends on knowing — precisely and repeatably — how much 13.5 nm energy reached the intermediate focus and the reticle. The detector that performs EUV photodiode 13.5 nm power and dose monitoring sits in one of the harshest optical environments in the fab: continuous high-flux EUV, energetic out-of-band plasma emission, debris, and an accumulated radiation dose that quickly reaches multiple G-rad over the tool’s service life.

New to these detector families? Compare them in our AXUV vs SXUV selection guide.

Opto Diode’s SXUV series silicon photodiodes are engineered specifically for this duty. The SXUV detector uses a metal-silicide entrance window in place of a conventional oxide window, which preserves internal quantum efficiency and delivers stable responsivity after the kind of accumulated dose that degrades ordinary silicon photodiodes. For ASML-ecosystem integrators, source builders, and metrology engineers who need a calibrated, drift-resistant, US-manufactured (ITW / ITAR-aware) detector, SXUV is the proven reference standard for 13.5 nm power and dose monitoring.

Request a quote or datasheet for SXUV detectors →

Why standard silicon photodiodes drift under EUV

A conventional silicon photodiode relies on a thin SiO₂ (oxide) passivation layer over the active junction. Under EUV and soft x-ray exposure, charge trapping and surface recombination in that oxide window steadily erode the near-surface collection efficiency. After only a few G-rad (SiO₂) of accumulated dose, an oxide-windowed detector loses the close-to-100% internal quantum efficiency it started with — and its responsivity calibration walks. In a metrology loop that controls dose-to-target, that drift translates directly into CD (critical dimension) variation and re-qualification downtime.

The SXUV architecture addresses the root cause rather than compensating for it downstream:

• Metal-silicide window mitigates surface recombination that plagues oxide-windowed devices, so near-surface charge is collected even after heavy exposure.
• Stable EUV responsivity is maintained after multi-G-rad dose, preserving the calibration that the dose-control loop depends on.
• Near-infinite radiation hardness to photons makes SXUV suitable for high photon flux and pulsed EUV environments.
• Broad 1 nm–~200 nm response covers 13.5 nm EUV plus the soft-x-ray and longer-wavelength bands used in source characterization and synchrotron reference work.

Where SXUV detectors sit in the EUV tool

SXUV photodiodes support the full chain of semiconductor lithography source and dose tasks:

• Source power monitoring at the intermediate focus — verifying clean 13.5 nm output from the LPP/DPP plasma.
• Dose monitoring and dose-to-target control — closing the exposure loop against a stable reference.
• Spot sensors and pulse-energy detectors for fast, shot-to-shot energy measurement.
• Beam diagnostics and collector qualification — characterizing reflectivity, uniformity, and degradation over time.
• Reference / transfer standards for periodic recalibration against synchrotron or NIST-traceable measurements.

SXUV detector options for 13.5 nm monitoring

A representative selection from the SXUV product family. Confirm exact active area, package, speed, and filter configuration on the current datasheet before designing in.

The TF135 integrated-filter variants are the direct answer to the “out-of-band rejection” requirement: a thin-film filter matched to 13.5 nm suppresses the broadband plasma emission that would otherwise contaminate a dose reading — built into the detector rather than added as a separate, alignment-sensitive optic. Browse the broader silicon detector portfolio and detection products for adjacent DUV (AXUV) and visible options.

SXUV silicon vs. SiC photodiodes for EUV

Silicon-carbide (SiC) detectors are sometimes positioned as the “solar-blind” alternative for EUV because their wide bandgap gives intrinsic visible-light rejection and very low dark current. Those are real properties — but for a production 13.5 nm power/dose loop, the decision should weigh maturity, traceability, and supply, not just bandgap.

The honest summary: SiC’s solar-blindness is genuinely attractive where stray visible light dominates. But SXUV’s metal-silicide window was created precisely to defeat the EUV-induced degradation that SiC vendors cite against *generic* silicon — and SXUV pairs higher 13.5 nm responsivity with integrated filtering, a documented fab track record, and a domestic supply chain. For a qualified, recalibratable production monitor, that combination is hard to displace. See our application notes for characterization detail.

US-based, ITAR-aware sourcing

Opto Diode manufactures SXUV detectors in the United States as part of ITW (Illinois Tool Works). For aerospace, defense, and leading-edge semiconductor programs with domestic-content, supply-security, or export-control requirements, that matters as much as the spec sheet: a stable, auditable, US source of supply with the engineering support to back long product lifecycles and custom configurations.

Frequently asked questions

What is the best photodiode for EUV 13.5 nm power and dose monitoring?

For production lithography, a radiation-hardened silicon detector built for stable EUV responsivity is the established choice. Opto Diode’s SXUV series uses a metal-silicide window that maintains calibration after multi-G-rad accumulated dose — the failure mode that drifts ordinary oxide-windowed silicon photodiodes. Model selection (active area, speed, integrated filter) depends on whether you are doing source power monitoring, fast pulse-energy sensing, or beam-position feedback.

How does SXUV stay stable after radiation exposure?

Conventional silicon photodiodes lose near-surface quantum efficiency as their SiO₂ window traps charge under EUV/soft-x-ray dose. The SXUV metal-silicide window suppresses that surface recombination, so the device keeps collecting near-surface charge and holds its responsivity calibration after dose levels measured in G-rad.

Should I choose SiC instead of silicon for EUV?

SiC offers intrinsic visible-light rejection and low dark current, which can help in stray-light-heavy setups. However, SXUV silicon typically delivers higher 13.5 nm responsivity, ships with optional integrated thin-film filters (TF135) for out-of-band rejection, and has a long, qualified track record in EUV tools plus a US supply chain. For most production dose/power loops, SXUV is the lower-risk choice. We’re happy to help you evaluate the trade-off for your tool.

Does Opto Diode offer integrated filtering for out-of-band light?

Yes. The SXUV100TF135 includes a thin-film filter tuned for 13.5 nm, rejecting broadband plasma emission so the detector reports clean in-band EUV without a separate, alignment-sensitive filter optic.

Are SXUV detectors US-made and suitable for controlled programs?

SXUV photodiodes are manufactured in the US by Opto Diode, an ITW company. We support customers with domestic-sourcing and ITAR-aware requirements; contact us to discuss export-control specifics for your program.

Request a quote or datasheet

Tell us your wavelength band, expected flux and accumulated dose, required active area, and whether you need integrated 13.5 nm filtering or beam-position sensing — and our engineers will recommend the right SXUV configuration or a custom design.

Contact Opto Diode for SXUV pricing, datasheets, and custom EUV detectors →

Want the full product line in one document? Download the Opto Diode product catalog.