Multi-Beam Mask Writer

A multi-beam mask writer patterns a mask using a massively parallel array of more than 250,000 individually-controllable electron beamlets firing simultaneously, finally breaking the resolution-versus-throughput tradeoff that limited every earlier mask-writing technology — delivering VSB-grade sub-10-nanometer resolution while cutting advanced-mask write time from over 20 hours down to well under 10. IMS Nanofabrication's MBMW systems, now part of KLA, are the production-proven implementation of this technology.

Multi-Beam: 250,000 Shots at Once Parallel beamlets break the serial-vs-resolution tradeoff every prior writer technology accepted. BEAMLET ARRAY each beamlet independently blanked on / off per pixel dim dots = blanked; bright dots = exposing Mask written in a raster scan all beamlets writing across a stripe simultaneously WRITE TIME, HEAD TO HEAD VSB (serial) 20+ hours Multi-beam (parallel) < 10 hours Same sub-10nm resolution as VSB — throughput gain without a resolution penalty. critical for EUV and curvilinear-ILT masks with huge shot counts WHY CURVILINEAR MASKS NEEDED THIS Inverse lithography optimization increasingly produces smooth, non-Manhattan curved mask shapes — fracturing those into VSB-compatible rectangles explodes shot count. Multi-beam writes curves directly without that shot-count penalty, which is exactly why it became essential as curvilinear OPC matured. Multi-beam is the first mask-writing technology that didn't make mask shops choose between resolution and speed.

Independent per-beamlet blanking is the single engineering achievement that makes massively parallel e-beam writing actually work, because it's what lets each of the 250,000-plus beamlets expose or skip its own assigned pixel completely independently of every other beamlet. Each beamlet in the array has its own dedicated blanking control, switching that individual beam on or off according to whether the mask pattern calls for exposure at that specific point — meaning the array as a whole can trace out an arbitrarily complex pattern across its entire stripe width in a single pass, with every beamlet contributing its own small piece of the overall image simultaneously rather than any single beam having to trace out the whole pattern alone.

Raster-scan writing, where the entire beamlet array sweeps across the mask in parallel stripes, is what actually converts the beamlet array's parallelism into a complete, finished pattern. As the array scans across a stripe of the mask, every beamlet continuously blanks on and off according to the pattern data for its specific position within that stripe — effectively each beamlet behaves like its own tiny, independent writer responsible for just its own narrow slice of mask area, with all of them moving and writing together. This architecture is precisely what multiplies effective write speed by roughly the number of active beamlets, compared to a single serial beam that has to cover the entire mask area alone.

Achieving sub-10-nanometer resolution with 250,000-plus simultaneous beams, matching what a single, far more easily controlled VSB beam delivers, required genuinely difficult engineering — this parallelism could easily have come at a real resolution cost, and multi-beam systems had to prove it didn't. Keeping every individual beamlet precisely focused, correctly positioned, and consistently calibrated across such a large array is a substantially harder engineering problem than maintaining the same precision for a single beam. IMS Nanofabrication's MBMW systems demonstrating resolution genuinely matching VSB's established benchmark, rather than a compromised version of it, was exactly the proof point mask shops needed before adopting multi-beam for their most demanding, highest-value production masks.

Curvilinear mask patterns — smooth, non-Manhattan shapes that inverse lithography optimization increasingly produces — are where multi-beam writing delivers an advantage no amount of VSB optimization can match, because curves simply don't fracture efficiently into VSB's rectangular shot primitives. Forcing a smooth curved edge into a sequence of small rectangles to approximate it well enough for VSB writing can explode shot count dramatically, directly inflating VSB write time for exactly the kind of advanced, curvilinear-OPC patterns that are becoming more common at the leading edge. Multi-beam's raster-scan, pixel-level exposure approach writes these curved shapes directly without needing to decompose them into rectangular shots at all, sidestepping the shot-count explosion that would otherwise make writing curvilinear masks on a serial VSB system impractically slow.

Multi-beam's write-time advantage matters most specifically for EUV and other advanced masks with extremely high shot counts, which is exactly the segment where it has gained the fastest production adoption. Cutting write time from over twenty hours down to under ten hours represents a genuinely significant improvement in mask-shop throughput and capital-equipment utilization for exactly the masks that otherwise occupy the most expensive writing equipment the longest. This cost-effectiveness case, combined with multi-beam's unique curvilinear-writing capability, is why it's increasingly displacing serial VSB specifically at the highest-value, highest-shot-count end of mask production, even as VSB remains well-suited to less demanding mask categories.

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