EUV Extreme Ultraviolet Lithography Wiki

Extreme Ultraviolet Lithography (EUV or EUVL) is an advanced semiconductor manufacturing technology used to print the smallest features on integrated circuits (ICs), particularly at leading-edge nodes such as 7nm, 5nm, 3nm, and below. EUV uses light with a wavelength of 13.5 nanometers, which is in the extreme ultraviolet spectrum, enabling much finer resolution than traditional deep ultraviolet (DUV) lithography.

EUV is a critical enabler of continued transistor scaling in the post-10nm era and has become the cornerstone of advanced logic and memory production for companies like TSMC, Samsung, and Intel.

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Overview

• Wavelength: 13.5 nm (compared to 193 nm in ArF DUV systems)

• Source: High-energy plasma from ionized tin (Sn) droplets

• Resolution: Enables patterning of features as small as 10nm and below

• Tools: Built primarily by ASML, the only company currently shipping EUV scanners

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Why EUV Matters

As traditional lithography approaches its resolution limits, EUV offers a step-function improvement in imaging capability:

By reducing the wavelength of light, EUV systems can directly print finer features, improving yield, reducing process steps, and lowering costs at advanced nodes.

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History and Development

Origins

EUV was first proposed in the late 1980s by academic and national research institutions (notably in the U.S., Japan, and Europe) as a next-generation lithography (NGL) candidate. Early research focused on plasma sources and multilayer mirrors.

Key Milestones

• 2000s: EUV championed by industry consortia (e.g., SEMATECH, IMEC)

• 2010: ASML delivers first pre-production EUV scanner (NXE:3100)

• 2018: TSMC uses EUV in high-volume manufacturing (7nm+)

• 2020s: Widespread adoption in 5nm and 3nm nodes by TSMC, Samsung, Intel

Key Supporters

• ASML: Only EUV scanner provider

• Zeiss: Supplies EUV optics and mirrors

• Cymer (ASML): Provides EUV light source (Sn LPP)

• Gigaphoton (Japan): Competing EUV light source R&D

• Pellicle and resist vendors: JSR, TOK, Merck, etc.

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How EUV Works

1. Light Source

• Laser-produced plasma (LPP) is created by firing a high-power CO₂ laser at tin droplets (Sn), creating plasma that emits EUV light at 13.5 nm.

• Only about 0.1% of the emitted light is usable, making source power and stability major engineering challenges.

2. Optics and Mirrors

• Since EUV light is absorbed by air and most materials, the system operates in vacuum and uses mirrors, not lenses.

• Mirrors are Bragg reflectors, made of alternating molybdenum and silicon layers.

• Zeiss manufactures these with atomic-level precision.

3. Mask and Pellicle

• EUV masks are reflective (not transparent) and contain multilayer mirror stacks.

• A pellicle is a thin protective film placed over the mask to protect it from particle contamination. EUV pellicle development is still a challenge due to heat and transmission constraints.

4. Photoresist

• EUV resists must be sensitive enough to capture patterns at low doses but robust enough to avoid stochastic defects (e.g., line-edge roughness, missing contacts).

• Metal-oxide and hybrid resists are under development to meet performance needs.

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Technical Challenges

EUV adoption required solving a complex array of physics and engineering problems, including:

1. Source Power

   • Original EUV tools had <10W source power; commercial tools now reach >250W.

   • Power levels directly affect throughput (measured in wafers per hour).

2. Mask Defects

   • Reflective masks are difficult to inspect and repair.

   • Mask blank defectivity and pellicle integration remain industry bottlenecks.

3. Resist Stochasticity

   • As features shrink, stochastic effects (random variability) in resist exposure increase defect risk.

   • High-NA EUV exacerbates this issue due to smaller process windows.

4. Tool Cost and Infrastructure

   • Each EUV scanner costs >$150 million and requires extensive fab modifications (e.g., vacuum chambers, cleanroom upgrades).

   • Only a few companies globally can afford EUV-scale fabs.

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EUV in High-Volume Manufacturing (HVM)

First Deployment

• TSMC introduced EUV in its N7+ (7nm+) process in 2019 for limited layers.

• Samsung deployed EUV in its 7LPP and 5LPE nodes.

Current Use

• EUV is now widely used for:

  • Contact layers

  • Metal-1 / metal-2 layers

  • Cut masks

  • Via and hole patterning

Benefits in Production

• Reduced multi-patterning complexity (e.g., LELELE or SAQP)

• Fewer masks, fewer etch steps, faster cycle time

• Enhanced CD (critical dimension) uniformity and lower variability

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High-NA EUV: The Next Leap

ASML is now developing High-NA EUV lithography with a numerical aperture (NA) of 0.55, up from 0.33 in current tools.

Key Benefits

• Improved resolution (<8 nm features)

• Enables 2nm and beyond

• Reduces stochastic variability

Challenges

• New mask size and format

• New resists with higher sensitivity

• New optical and mechanical tolerances

• Tools expected to cost >$400 million

Timeline

• ASML EXE:5000 and EXE:5200 High-NA tools expected in pilot use by 2025–2026

• Target nodes: Intel 18A, TSMC A14 or beyond, Samsung 2nm GAA

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Global Impact and Strategic Importance

EUV lithography has become a strategic national asset due to its role in advanced semiconductor production.

• ASML (Netherlands) holds a global monopoly on EUV tools.

• Geopolitical sensitivity has led to export restrictions to certain countries (e.g., China).

• TSMC, Intel, Samsung dominate access to EUV, shaping global chip supply chains.

EUV has also enabled:

• Leadership in mobile SoCs (Apple, Qualcomm)

• High-performance computing (AMD, NVIDIA)

• Advanced memory (SK hynix, Micron)

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Future Outlook

EUV is poised to dominate lithography for the next decade and beyond, with expected developments including:

• Broader EUV adoption across layers and nodes

• High-NA transition around 2025–2027

• Stochastic defect suppression through new materials and AI

• Resist innovation (metal-oxide, molecular, CAR)

• Multi-beam mask writers and improved pellicles

EUV is not just a tool—it’s a technological and economic inflection point in the future of semiconductor manufacturing.

🕰️ EUV Lithography Technology Timeline

https://semiwiki.com/category/lithography/

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