[Thin Film Part8] BEOL Interconnect 2

Welcome back to the "Thin Film Series," where we unravel the complexities of semiconductor device fabrication. In this eighth episode, we shift our focus to Copper (Cu) and low-k materials, which are central to the Back-End-Of-Line (BEOL) interconnect technology in state-of-the-art semiconductor chips. Discover why copper has emerged as the dominant material and what future innovations may surpass it. This episode is designed to cater to everyone from beginners to seasoned professionals, aiming to enhance your understanding of BEOL interconnect technology and the critical role of thin film deposition in modern electronics. Make sure to like, subscribe, and hit the bell icon to keep up with our insightful content. Scroll down for a detailed outline of this episode; you can click any timestamp to jump directly to a specific section.

Episode Outline:

1. Introduction to Copper and Low-k Materials in BEOL Interconnect Technology
[0:00] Introduction: Setting the stage for copper's role and the rise of low-k materials in advanced semiconductor design.
[1:30] Understanding RC Delay: Basics of signal delay issues in BEOL interconnects.
[3:55] Importance of BEOL Delays: Exploring why delays are more critical at smaller nodes and the necessity for Cu and low-k materials.
[6:10] Multi-layer Metallization: Strategies to manage RC delay effectively.
[7:50] BEOL Terminology: Demystifying terms used in multi-layer metallization schemes.
[10:05] Evolution of Low-k Materials: Tracing IBM's advancements from 1997 to 2008.

2. Cu Electrodeposition
[13:30] Aluminum vs. Copper: Analyzing the advantages and disadvantages.
[15:25] Cu Damascene Process: Details on copper electroplating and CMP.
[17:00] Electroplating Reactor Components: A closer look at the cell setup and its parts.
[18:15] Additives in Cu Plating: Roles of accelerators, suppressors, and levelers.
[20:20] Achieving Uniformity: The function of High Resistance Virtual Anode (HRVA) in Cu plating.
[24:15] Edge Bevel Removal: Techniques for removing copper from the wafer bevel area.
[25:45] Chemical Monitoring Systems: Methods for tracking the concentration of additives.
[29:00] Copper Annealing: Discussing the role of annealing post-Cu plating.
[31:25] Dendrite Growth: Addressing the risks of dendrite defects after Cu CMP.

3. Cu Interconnect
[32:55] Dual Damascene Process: Comparing single and dual damascene approaches.
[34:05] Via First vs. Trench First: Analyzing the schemes and their risks to low-k materials.
[35:30] Process Damage: Comparing the effects of VFDD and TFDD on low-k materials.
[38:10] TFDD Process Cycles: Detailing the repetitive cycle process for multi-layer Cu metallization.
[40:05] Applied Materials' Cluster Tool: Utilizing PVD for barrier metal and seed Cu.
[42:50] TaN/Ta Liner Functionality: Explaining the role of these materials as barrier metals.
[44:50] Testing TaN Barrier Efficiency: CV BTS methodology.
[47:20] Innovative Materials for Cu Plating: Exploring less void-prone liners like Ta and Ru.
[48:35] Predicting Electromigration: Using Black's Equation for lifetime estimation.
[51:20] Electromigration Failure Modes: Understanding void formation along electron paths.
[53:10] Electromigration Solutions: Benefits of Mn-doped PVD Cu seed and Co liner & capping.
[55:15] Selective CVD Co Process: Highlighting Volta CVD Co from Applied Materials.
[57:30] Wrap Around Cobalt Process: Innovations from Applied Materials.
[1:00:05] Cu Reflow on Ru Liner: Addressing electromigration.
[1:02:35] Stress Migration in Copper Contacts: Examining the implications.
[1:04:50] TiN Hardmask Issues: Discussing challenges in dry etching.

4. Alternative Metal Technologies
[1:08:40] Resistivity Challenges: Addressing Cu limitations at sub-39nm line widths.
[1:11:00] Exploring Alternatives: Metals suitable for narrow line widths.
[1:13:05] Metallization Trends: Recent advancements in approaches.
[1:15:25] Advanced BEOL Interconnects: Exploring thin barrier metal technologies.
[1:17:10] Selective Barrier Schemes: The shift towards selective barriers.
[1:19:00] Ru-Cu Hybrid: Innovations in hybrid schemes.
[1:21:15] Semi-Damascene with Ru: Advancements in Ru applications