[EUVL Part4] EUV Mask

Dive deeper into the intricacies of Extreme Ultraviolet Lithography (EUVL) with our ongoing series. This fourth episode shifts the focus towards EUV mask technology, a pivotal element in high-volume manufacturing (HVM). As we explore this critical component, we'll uncover how EUV masks differ from traditional optical masks and the unique challenges they bring to semiconductor fabrication. Below are the main chapters of this video. Click on any timestamp to jump directly to the desired chapter.

1. Introduction: Distinguishing Optical and EUV Masks
[02:10] Comparative Analysis: Transmissive ArF vs. Reflective EUV Mask.
[05:05] Technical Challenges: Transitioning from ArF to EUV Mask.

2. Mask Structure: Exploring the Architecture of EUV Masks
[09:20] Substrate for EUV Mask: Utilizing Low Temperature Expansion Material (LTEM).
[10:45] Mo/Si Multilayer (ML) & Capping Layer: Acting as the reflective mirror.
[12:20] EUV Reflectivity Behavior: Variations as a function of ML pair numbers, capping layer, chief-ray-angle (CRA), and thermal heating.
[15:50] Absorber Layer & DUV ARC: TaBN absorber & TaBO ARC for patterned EUV masks.
[19:05] Absorber Material for EUV Binary Intensity Mask (BIM) & Phase Shift Mask (PSM).
[21:25] Backside Conductive Coating (BSC): Ensuring clamping to the reticle stage with electrostatic chucking.
[24:15] Out-of-Band (OOB) Problems at Image Border.
[26:15] Solution to OOB Problem: ML-etched Black Border (BB) or Hybrid BB.

3. Defect Control: Tackling Defect Density in EUV Masks
[29:20] Blank Mask Production Flow: Substrate → BSC → MLM → Absorber.
[33:30] Key Requirements and Defect Challenges of EUV Blank Mask Layers.
[36:25] Ion Beam Deposition (IBD): Achieving low defect density in Mo/Si MLM.
[39:20] EUV Blank Mask Defects: Multilayer and Substrate LTEM defects.
[41:45] Chronological Reduction in Blank Mask Defect Density.
[45:30] Mask Defect Avoidance (MDA) Technology: An innovative solution for blank mask defects.
[48:40] Actinic Blank Inspection (ABI): Inspecting defects on EUV blank masks at EUV wavelengths.
[51:00] ABI for MDA: High magnification mode for precise defect positioning.

4. Pellicle: Safeguarding the Mask
[53:15] EUV Pellicle Membrane Challenges: Addressing thickness and local heating issues.
[58:05] EUV Pellicle Development History: From SiN to Si, Metal Silicide, and Carbon Nanotube.
[1:03:05] Pellicle Mounting on EUV Mask: ASML’s assembly method using Fixture & Stud.
[1:06:05] EUV Dual Pod: Functioning as a Removable Pellicle in EUV Scanners.