Thomas Achleitner | EV Group (EVG): How do you align micro-lens arrays to a 50µm-thick microLED wafer at ±500nm and still package it?
12:49 - 14:24
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How do you align micro-lens arrays to a 50µm-thick microLED wafer at ±500nm and still package it?
Micro-lens packaging for microLEDs is a co-packaged optics application where short-distance communication matters. The divide-and-slower approach will be essential in the future. A process is available to imprint micro-lens arrays directly on the functional microLED wafer, avoiding separate handling. This matters because co-packaged optics demand tight optical alignment between emitters and lenses, and the wafer-level route keeps the lens array in the same process flow as the device.
The microLED wafer arrives at 50 microns thickness on a thin frame. Micro-lens arrays are imprinted with alignment precision of plus or minus 500 nanometers. That alignment budget is critical: any lateral offset between lens and emitter degrades coupling into the lens and the subsequent optical path. The imprint step therefore combines sub-micron registration with wafer-level processing, which is a different challenge from die-level lens attach.
With the very same process, attachment structures are bonded for a later fan-out attach. This makes it easier to package the microLED array later on the device. The imprint process is still being worked on. Beyond co-packaged optics, the demand for augmented reality in that field is a driver. So the combination of direct imprint on a 50-micron functional wafer, ±500-nanometer alignment, and integrated attach structures addresses both the optical and the packaging side.
In this short video, you can learn:
* Micro-lens arrays are imprinted directly on functional microLED wafers that arrive 50 microns thick on a thin frame.
* Alignment between the imprinted lens array and the microLEDs is held to plus or minus 500 nanometers.
* The same imprint process bonds attachment structures for later fan-out attach, simplifying packaging of the microLED array on the device.
📋 **Clip Abstract** Micro-lens arrays are imprinted directly on functional microLED wafers, 50 microns thick on a thin frame, with alignment of plus or minus 500 nanometers for co-packaged optics. The same process bonds attachment structures for later fan-out attach, easing packaging, while the divide-and-slower approach and augmented reality demand drive the work.
About the speaker:
* Speaker: Thomas Achleitner
* Company: EV Group (EVG)
* Event: Eindhoven 2026
* Location: High Tech Campus, Eindhoven
#MicroLensArray, #NanoimprintLithography, #MicroLEDPackaging, #FanOutAttach, #ARDisplays, #CoPackagedOptics
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From Nanostructures to New Realities: The Role of Nanoimprint Lithography in AR
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02:41 - 04:47
A single AR master can cost hundreds of thousands of euros — how do you replicate it 21 times on 300mm without drift?
A single AR master can cost hundreds of thousands of euros — how do you replicate it 21 times on 300mm without drift?
Mastering starts from a single die-hard master, which the step-and-repeat system upscales to fully populate the master — a three-picture process flow on paper. Behind it sit more than six years of process development: a reliable polymer combination, a system that moves reliably, and demolding done precisely and carefully. That matters commercially, because one hard master can cost a few hundred thousand euros, particularly when it is a single, super-fancy die.
Scaling a single die to 300 millimetre or panel size is where this becomes unavoidable: there is currently no other way to master it, which is why the approach is so important for 300 millimetre and beyond. On the slide from Jason, 24 dies were mentioned; this work shows at least 21, and shuffling the layout could squeeze in one or two more.
FBM metrology across those 21 dies shows no big change from the first die to the last die, confirming a very stable polymer combination for the step-and-repeat mastering shop that is long-lasting for the master itself. Critically, it is compatible with downstream processing such as the antistick layer and other preservation strategies, and there is considerable flexibility in how the step-and-repeat hard master is designed.
In this short video, you can learn:
* More than six years of process development went into the polymer combination and precise, careful demolding required for reliable step-and-repeat mastering.
* One hard master can cost a few hundred thousand euros, so replicating it rather than remastering it is where the cost is saved.
* FBM metrology across 21 dies showed no big change from the first die to the last, and the stack stays compatible with antistick layers and preservation strategies.
📋 **Clip Abstract** Step-and-repeat mastering upscales a single die-hard master to 300 millimetre and panel formats, placing at least 21 dies per master with no big change from the first die to the last. That stability rests on six years of polymer and demolding development, and on compatibility with antistick layers and other downstream preservation steps.
About the speaker:
* Speaker: Thomas Achleitner
* Company: EV Group (EVG)
* Event: Eindhoven 2026
* Location: High Tech Campus, Eindhoven
#StepAndRepeatMastering, #AntistickLayer, #FBMMetrology, #PolymerDemolding, #ARDisplays, #ARWaveguides
09:03 - 11:30
Why does inkjet coating beat spin coating for AR gratings — and how thin can the residual layer get?
Why does inkjet coating beat spin coating for AR gratings — and how thin can the residual layer get?
Spin coating leaves a residual layer whose thickness tracks the grating height, because that is the nature of the process. Inkjet coating changes the outcome: it keeps the residual layer low and genuinely uniform, independent of the structure height. The stated goal is to further increase the efficiency of the AR effect. That uniformity, not throughput, is the reason the coating step matters for diffractive waveguide performance.
A comprehensive study was run with partner Techcent in Dresden, which fabricated a fancy master carrying an in-coupler grating, an extended grating and an out-coupler grating. The in-coupler carries staircase gratings. The extended grating has height modulation, progressing from 60 nanometres down to 160 nanometres. The out-coupler has a non-linear height progression from 50 to 200 nanometres. Duty cycle and pitch also change along the gratings.
Inkjet coating was used to achieve a really thin, homogeneous residual layer thickness below the structures. Results: on the out-coupler grating, the most sensitive case, a residual layer thickness in the range of 50 nanometres was achieved, very constant and very thin. The extended and out-coupler gratings gave 60 and 45 nanometres. Everything was processed with high refractive index materials, so the process is up and running and ready for demo in the competence centre.
In this short video, you can learn:
* Spin coating ties residual layer thickness to grating height, while inkjet coating decouples them.
* The Dresden master combined staircase in-coupler gratings, a height-modulated extended grating and a non-linear 50–200 nm out-coupler grating with changing duty cycle and pitch.
* Constant residual layers of 50 nm on the most sensitive out-coupler grating, and 60 and 45 nm on the extended and out-coupler gratings, were achieved using high refractive index materials.
📋 **Clip Abstract** Inkjet coating replaces spin coating to keep a low, uniform residual layer under diffractive AR gratings regardless of structure height, raising efficiency. A Techcent Dresden master with staircase, height-modulated and non-linear gratings was imprinted in high refractive index material, delivering constant residual layers of about 50, 60 and 45 nanometres and a demo-ready process.
About the speaker:
* Speaker: Thomas Achleitner
* Company: EV Group (EVG)
* Event: Eindhoven 2026
* Location: High Tech Campus, Eindhoven
#NanoimprintLithography, #InkjetCoating, #HighIndexMaterials, #ResidualLayerThickness, #ARWaveguides, #Nanofabrication
06:37 - 08:48
Can you imprint both sides of a 12-inch wafer to ±5 arc seconds without destroying the first layer?
Can you imprint both sides of a 12-inch wafer to ±5 arc seconds without destroying the first layer?
Dual side imprinting is a hot topic because it enables different structures on the first side of the wafer and, after flipping the substrate, on the back side. The flow looks simple: take the first-side-imprinted wafer, coat a protective layer over side one, flip the wafer, process side two, then remove that protective layer. The result is two precisely aligned nanoimprinted layers.
Along that process flow sit several question marks. How compatible is the protective layer with the imprinting polymer? How do you remove the protective layer after imprinting without destroying the underlying polymer? And what about the angular alignment accuracy? These questions sit between the clean-looking flow and a working dual-side process, each one tied to material choices and tool behaviour rather than to the imprint step alone.
The answers come from process development in the lab. An off-the-shelf protective layer coating has already been demonstrated with high refractive index and low refractive index materials, and it is compatible with many resins. A two-chemistry clean removes that protective layer coating after second-side imprinting. Angular alignment accuracy reaches ±5 arc seconds on 12-inch, which customer information says is more than enough to increase optical output.
In this short video, you can learn:
* Dual-side imprinting requires flipping the wafer between front-side and back-side structures, with a protective layer in between.
* The open questions are protective-layer compatibility with the imprint polymer and its removal without destroying the underlying polymer.
* Angular alignment reaches ±5 arc seconds on 12-inch, which customer information says is enough to increase optical output.
📋 **Clip Abstract** Dual-side nanoimprint lithography enables different structures on both sides of a wafer, using a protective coating and a wafer flip between the two imprints. Process development has shown an off-the-shelf protective layer compatible with high- and low-refractive-index materials and many resins, a two-chemistry clean for its removal, and ±5 arc seconds angular alignment on 12-inch, which customer information says is more than enough to increase optical output.
About the speaker:
* Speaker: Thomas Achleitner
* Company: EV Group (EVG)
* Event: Eindhoven 2026
* Location: High Tech Campus, Eindhoven
#DualSideImprinting, #ProtectiveLayerCoating, #HighRefractiveIndex, #AngularAlignment, #NanoimprintLithography, #ARDisplays