UV-LED technology in Photomask and Reticle Inspection

Innovate your high-precision inspection process.

Our UV-LED light sources leverage flexibility and accuracy in photomask and reticle inspection

An error-free reticle or photomask is crucial in achieving a high yield in photolithography applications. Reticle defects and contaminations lead to pattern placement errors being repeatedly replicated on production substrates. Reticle inspection systems help mask shops to qualify their photomasks. They are equally important for fabs: Chipmakers, flat panel display (FPD), and PCB manufacturers need to assess incoming reticle quality and re-qualify reticles periodically during production to protect their yield by reducing the risk of printing defective wafers and other substrates.

With the extensive use of photolithography in many different applications, the variety of reticles is almost endless. Primelite focuses on inspection tools using near UV (NUV), visible light (VIS), or near infrared (NIR)  to identify defects and contaminations on large photomasks. We provide very powerful and flexible LED solutions to replace conventional mercury and xenon discharge lamp technology in these systems.

Integration of our LED light sources in Photomask Inspection

With the increasing demand for high-resolution flat panel displays in applications such as smartphones and tablets, our powerful LED solutions are particularly beneficial in reticle inspection tools for large photomasks. There are three convincing aspects for OEMs to integrate Primelite’s high-performance LED systems into their inspection equipment:

  1. Our fiber-coupled Advanced Light Engines ALE/1 and ALE/3 offer fantastic flexibility: There is virtually no limitation to the movability or positioning of the light source in your machine, thanks to the concept of using high-transmission LED light guides. In some existing installations, these light guides are up to 20 m long. Please see Primelite Performance Optics for additional information.
  2. Leading-edge OLED FPDs have a higher density of TFT transistors to achieve better resolutions, which requires smaller feature sizes produced by high-end photomasks. Reliable inspection of these reticles needs better defect detection sensitivity, which you can achieve by shifting the wavelengths of the inspection radiation from VIS to near UV. Primlelite’s advanced LED light sources  show excellent performance in the spectral range between 350 and 450 nm.
  3. Our LED exposure solutions’ superb output stability (both short- and long-term) adds to the accuracy and consistency of your reticle inspection results.
Primelite UV-LED Integration Reticle Inspection
Reticle Inspection Setup with Primelite UV-LED Light Source ALE/1

Precision mono and multi-wavelength output

While other LED exposure solutions only provide a narrow wavelength band of inspection light (e.g., 385±15 nm), using our advanced LED systems, you can take advantage of an entirely customizable broadband output spectrum. Apart from central wavelengths matching the i-, h-, and g-line (365/405/436 nm) of conventional discharge lamps, you can complement the spectral range with additional VIS (e.g., blue and green) components. With our Advanced Light Engine ONE you can combine up to 5 high-power and individually feedback-controlled LEDs into a single optical path. Economic single- and dual-wavelength exposure setups are available based on our fiber-coupled UV-LED light source ALE/3.

Primelite Fiber-Coupled UV-LED Spot Light Source ALE ONE: Spectral Power vs. Discharge Lamp
ALE/1 vs. 200 W Discharge Lamp: Spectral Power (CWL 365/405/436 nm)

Output performance compared

Output Power [mW]1Broad­band
(350-450 nm)
i-line
(355-385 nm)
ALE/1.3 (CWL 365, 405, and 436 nm) 230,00010,000
ALE/3.2 (CWL 365 and 405 nm) 213,0006,500
200 W Mercury Discharge Lamp (typical values)7,5003,000

1Power output measured at end of light guide (active core dia. 6.5 mm, length 1.5 m), deviation of ±10% possible.
2CWL of emitters: 367.5±2.5 nm, 402.5±2.5 nm, and 435.0±2.5 nm.

Primelite Fiber-Coupled UV-LED Spot Light Source ALE ONE
Primelite Fiber-Coupled UV-LED Spot Light Source ALE/1 and LED Light Guide

Why ALE ONE and ALE THREE for Photomask Inspection:

Advanced Light Engine
ONE

ALE/1 fiber-coupled UV-LED spot light sources are the industry’s benchmark for customizable broadband exposure spectrum with superb stability.

Advanced Light Engine
THREE

Our ALE/3 UV-LED spot light source is an economic and low footprint replacement for discharge lamps in reticle inspection applications.

LED
Light Guides

Learn more about our high-transmission LED light guides and how their capabilities can leverage your photomask inspection setup.

Talk to us about your application!