UV-LED Illumination in Wafer Steppers

Out with Conventional Mercury Discharge Lamps, in with UV-LED Tech in Wafer Steppers

Redefining Efficiency in Advanced Packaging Processes with Primelite's UV-LED Wafer Stepper Illuminators

Broadband wafer steppers, variously known as 1X steppers and mini-steppers, are essential to advanced packaging use cases such as fan-out wafer-level packaging (FOWLP), wafer-level chip-scale packaging (WLCSP), and through silicon via (TSV). These highly specialized step-and-repeat lithography systems serve to create complex microstructures such as MEMS and compound semiconductors.

Our broadband UV-LED light sources ALE/1 and ALE/1C are a perfect fit if you want to upgrade your stepper to UV-LED illumination. Adopting our solution gives you full flexibility on the choice of photosensitive advanced packaging materials you may need to apply in your process.

Ours is a unique setup: Combining individual LED-Modules around the i-, h-, and g-line into one optical path gives you total control over the spectral composition of your broadband exposure in the 350 – 450 nm range. We provide high-power radiation output, so you can replace any conventional mercury arc lamp rated for up to 1,000 W – and even higher. Forget about tool downtime while swapping lamps and the hassle of mercury waste disposal. All that is a thing of the past with our UV-LED technology integrated in your lithography tool.

Our systems prove their merits every day in countless semiconductor manufacturing scenarios. You can achieve resolutions down to 1 µm or even in the sub-micron range by using our high-performance UV-LED illumination technology in a wafer stepper. Its excellent output stability and reliability can help you boost system throughput (WPH) while cutting ownership costs.

Integrating Our UV-LED Illuminators into Broadband Wafer Steppers

Our UV-LED exposure solutions replace the conventional lamp house. You no longer need the primary beam-folding mirror, heat sink to absorb radiation beyond 450 nm, shutter, and filters. In many cases, our LED Performance Optics are also an economical alternative for legacy homogenizing / condensing components. You have two options for upgrading your wafer stepper from mercury arc lamps to our UV-LED illumination:

  1. If your design envelope is challenging, be sure to check out our all-in-one fiber-coupled UV-LED light source ALE/1, featuring flexible LED Light Guides to be coupled into broadband steppers’s integration optics.
  2. Our high-power UV-LED Exposure System ALE/1C features a distributed design. The control subsystem (CSS) and the small-footprint exposure subsystem (ESS) are separate components. The ESS replaces the wafer stepper’s conventional lamp house.

We can customize both solutions to fit your equipment perfectly. Retrofitting your existing system is also an option.

Primelite UV-LED Exposure System ALE ONE C: Spectral Power CWL 365, 405, 436
Primelite UV-LED Exposure System ALE ONE C: Spectral power (CWL 365 / 405 / 436 nm)

I-Line, H-Line, and G-Line Combined for Full Power

Many photolithography applications rely on broadband exposure encompassing i-, h-, g-line (CWL 365 / 405 / 436 nm) radiation. Our UV-LED exposure systems provide similar spectral output to that of mercury discharge lamps, so upgrading your photolithography process to UV-LED exposure requires minimal adaption. Setups with two central wavelengths (365 / 405 nm or 405 / 436 nm) are also available.

Output Performance Compared

Output power [mW]Broad­band
(350 - 450 nm)
(355 - 385 nm)
Mercury discharge lamp (typical values)
  500 W25,00012,000
  1,000 W50,00025,000

1Standard mode; Performance mode with chiller delivers additional 20% output

Ultra-precise Exposure

Our UV-LED exposure solutions’ switching time (0 to 100%) is less than 1 millisecond. An internal closed-loop feedback control system keeps the radiation output constant over short cycles as well as over longer exposure cycles. These features combine to achieve ±0.2% dose accuracy for short 50-millisecond shots using nothing more than a timer. Accuracy even increases with longer exposure cycles.

Primelite Lithography UV-LED Exposure System Advanced Light Engine ONE C
Primelite lithography UV-LED Exposure System ALE/1C (controller and exposure subsystem)

Why Primelite's UV-LED Illuminators for Wafer Steppers:

Advanced Light Engine

Our ALE/1 is the benchmark fiber-coupled UV-LED spot light source when it comes to reliable output and a customizable broadband exposure spectrum.

Advanced Light Engine

Achieve resolutions down to 1 µm – or even in the sub-micron range – with our industry-proven UV-LED Exposure System ALE/1C.

Talk to us about your use case!