[Photolithography Part6] Photomask (2 of 2)

Welcome back to our in-depth exploration of photomask technology in optical lithography for silicon wafer semiconductor fabrication. Continuing from the first part of this sixth episode, where we examined the photomask fabrication process, we now shift our focus to the Front-End of Line (FEOL) metrology and the Back-End of Line (BEOL) processes. This segment is dedicated to delving deeper into the critical aspects of CD and Registration control, alongside defect inspection and repair-key areas that ensure the precision and functionality of photomasks used in high-volume manufacturing. Below, we outline the main chapters of this video. Click on any timestamp to jump directly to that section.
1. FEOL Metrology - Photomask Metrology
[00:10] Photomask Quality Indices: Exploring CD, Registration, Optical Density (OD), and Defects.
05:05] Photomask CD Measurement: Discussing Mean To Target (MTT), CD Uniformity (CDU), and Mask Error Enhancement Factor (MEEF).
[09:00] CD Metrology: Comparing Mask CD-SEM with AIMS Intensity CD.
[13:05] Deep Dive into AIMS Tool from Zeiss: Analyzing aerial image measurement systems.
[16:35] Overlay vs Registration: Understanding the differences and impacts.
[17:40] Standard Registration Measurement: Techniques and tools.
[19:40] Local Registration (LReg) & In-Die Registration: Precision techniques in registration measurement.
[23:45] Working Principle of Registration Measurement Tool: Exploring Ethalon, Free Working Distance, and illumination techniques.
2. FEOL Metrology - CD & Registration Control
[31:35] ITRS Table for Optical Mask Requirements: For CD and registration control.
[33:50] Closed Loop for CD Control (CDC): Integrating Zeiss’ AIMS & ForTune.
[35:35] Closed Loop for Registration Control (RegC): Utilizing Zeiss' PROVE & ForTune.
[37:30] Zeiss' ForTune System: Detailing Shade-In Element for CDC, and Deformation Elements forRegC.
[41:05] How CDC Works: Principles of CD control with Shade-In elements.
[44:05] Improving ACLV using CDC: Techniques for multiple CDC applications.
[46:05] How RegC Works: Principles of registration control with X/Y-Mode Signature (MS).
[49:10] Application of Mask RegC: Addressing scanner non-correctable errors (NCE) like scanner lens and reticle heating fingerprints.
3. BEOL Process - Defect Inspection & Repair
[52:35] Photomask Defect Challenges: For smaller technology nodes.
[55:20] Photomask Defect Types: Explaining Clear/Opaque and Phase Defects.
[55:45] Photomask Defect Inspection Tool: Techniques like Die-to-Die (D2D) and Die-to-Database (D2DB) Inspection.
[1:03:05] Photomask Defect Inspection Tool: Details on Broad-band Plasma (BBP) Light Source and Time Delay Integration (TDI) Sensor.
[1:08:25] Discussion on Printable Defect Size
[1:10:45] Defect Repair: Techniques including Laser-based, Focused Ion Beam (FIB), Micro-machining AFM, and Electron-beam based Repair.
[1:15:55] Zeiss' AIMS and MeRiT Repair Tools: Exploring MeRiT for repair and AIMS for repair verification.
4. BEOL Process - Photomask Maintenance
[1:17:35] Defect Printing Principle: Analysis with and without pellicle.
[1:20:50] Detailed Structure of Pellicled Reticle
[1:26:25] Haze Defect Formation Mechanism
[1:28:55] Reticle Cleaning Process
5. Wrap Up
[1:31:40] Reviewing the First and Second Parts of This Episode: With a mind map and keywords.

[@justhujia]

Studying hard in your video and looking forward to your new works！

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