Periodic Reporting for period 1 - HOLISTEP (SUB-WAVELENGTH HOLOGRAPHIC LITHOGRAPHY STEPPER FOR INTEGRATED CIRCUIT PRODUCTION)
Berichtszeitraum: 2024-01-01 bis 2025-06-30
For decades, Projection Lithography (PL) has driven semiconductor miniaturisation in line with Moore’s Law, but its limits—2D-only imaging, a depth–resolution trade-off, and rising costs—now constrain progress. Scalable 3D manufacturing with PL has proved impractical, leaving industry without an affordable, high-precision method for complex structures.
HoLiSTEP addresses this gap with sub-wavelength Holographic Lithography (HL), a disruptive method for wafer-scale 2D and 3D patterning at 200 nm resolution and 25 nm overlay precision. HL produces complex structures in a single exposure, tolerates mask defects, and removes the need for toxic materials and complex projection optics, offering major gains in cost, sustainability, and design freedom.
The project’s core breakthrough is integrating a 20 W, 345 nm UV fibre-based laser with 1.5 m coherence length, a novel alignment system achieving <25 nm overlay, and adaptive optics providing λ/20 correction under operational thermal load. These subsystems form the HS-345 industrial prototype, to be validated in a cleanroom for ≥100 wafers/hour throughput. A 388 nm test bench has already demonstrated 1.2–1.6 μm resolution, with optimisation expected to meet the 200 nm target.
HoLiSTEP addresses this gap with sub-wavelength Holographic Lithography (HL), a disruptive method for wafer-scale 2D and 3D patterning at 200 nm resolution and 25 nm overlay precision. HL produces complex structures in a single exposure, tolerates mask defects, and removes the need for toxic materials and complex projection optics, offering major gains in cost, sustainability, and design freedom.
The project’s core breakthrough is integrating a 20 W, 345 nm UV fibre-based laser with 1.5 m coherence length, a novel alignment system achieving <25 nm overlay, and adaptive optics providing λ/20 correction under operational thermal load. These subsystems form the HS-345 industrial prototype, to be validated in a cleanroom for ≥100 wafers/hour throughput. A 388 nm test bench has already demonstrated 1.2–1.6 μm resolution, with optimisation expected to meet the 200 nm target.
Work began with defining detailed system requirements based on state-of-the-art analysis and application needs in photonics, MEMS, advanced packaging, sensors, and meta-optics. A high-power spun tapered double-clad fibre amplifier achieved 110 W average power at 1040 nm, producing 9 ns pulses at 100 kHz with 1.1 mJ energy, M² < 1.2 and >97.5% polarisation purity. Temporal coherence lengths up to 177 cm exceeded the 1.5 m target after frequency conversion to 345 nm. The adaptive optics module, incorporating a 37-channel deformable mirror with R=99% coating at 347 nm, achieved λ/20 correction under simulated 20 W thermal load. The alignment system was prototyped and verified, delivering sub-10 nm coordinate accuracy, translating to <25 nm overlay in final use.
The 388 nm test bench was assembled, aligned, and validated through initial exposures, confirming system functionality and identifying optimisation routes. The first binary amplitude holographic mask was designed, fabricated, coated, and characterised to inform improved second-generation masks. A rigorous Maxwell-based vector diffraction engine was implemented and validated, while experimental resist characterisation at 388 nm enabled accurate exposure modelling for binary and grayscale mask synthesis.
By the end of the period, all major technical building blocks—high-coherence laser, precision alignment, adaptive optics, validated modelling tools, and first-generation masks—were delivered. Integration with frequency doubling and process optimisation will lead to the final cleanroom demonstration.
The 388 nm test bench was assembled, aligned, and validated through initial exposures, confirming system functionality and identifying optimisation routes. The first binary amplitude holographic mask was designed, fabricated, coated, and characterised to inform improved second-generation masks. A rigorous Maxwell-based vector diffraction engine was implemented and validated, while experimental resist characterisation at 388 nm enabled accurate exposure modelling for binary and grayscale mask synthesis.
By the end of the period, all major technical building blocks—high-coherence laser, precision alignment, adaptive optics, validated modelling tools, and first-generation masks—were delivered. Integration with frequency doubling and process optimisation will lead to the final cleanroom demonstration.
HoLiSTEP has established HL as a credible, high-performance alternative to PL. Its ability to generate high-resolution 2D and 3D patterns in one step, combined with mask defect tolerance and reduced dependence on complex optics and toxic materials, offers lower costs, extended mask lifetimes, and a smaller environmental footprint. These benefits open adoption to SMEs as well as major manufacturers, with applications in semiconductors, MEMS, MOEMS, photonics, advanced packaging, and meta-optics.
Strategically, HoLiSTEP strengthens EU industrial resilience by providing a domestically developed lithography platform that reduces reliance on non-EU suppliers. The combination of cost, sustainability, and technical capability positions HL as a transformative enabling technology for future high-resolution manufacturing.
Strategically, HoLiSTEP strengthens EU industrial resilience by providing a domestically developed lithography platform that reduces reliance on non-EU suppliers. The combination of cost, sustainability, and technical capability positions HL as a transformative enabling technology for future high-resolution manufacturing.