Core Viewpoint - The article discusses the evolution and significance of on-die interconnects in advanced packaging technologies, highlighting the transition from traditional single-die packages to multi-die packages that require internal interconnects [2][6]. Group 1: On-Die Interconnects - On-die interconnects have become essential for signal transmission within chips, especially as advanced packaging allows for multiple components within a single package [2][6]. - The internal interconnect methods can be categorized into bonds and various interconnect structures, with bonding being a direct connection to the die or package substrate [2][6]. Group 2: Bonding Techniques - Bonding methods are broadly classified into three categories: wire bonding, C4 bump bonding, and direct bonding, with wire bonding being the oldest and still widely used for small dies [6][7]. - C4 bonding involves connecting solder balls directly to the die pads, allowing for higher connection density, particularly in BGA packages [20][24]. - Hybrid bonding, a newer technique, allows for direct bonding of metal pads without intermediary materials, enhancing connection reliability [38][39]. Group 3: Substrate and Interposer Technologies - Substrates in advanced packaging are similar to PCBs, consisting of alternating layers of metal wiring and dielectric materials, facilitating signal routing [47][50]. - Interposers serve as intermediary layers that enable multiple chip connections, improving signal integrity and reducing communication power consumption [58][61]. - The use of silicon interposers is prevalent due to their high wire density, although they are more expensive than organic materials [63][64]. Group 4: Material Considerations - The choice of materials for substrates and interposers is critical, with options including organic materials, silicon, and glass, each offering different performance characteristics [51][68]. - Organic interposers are being explored as a cost-effective alternative to silicon interposers, with ongoing developments in their manufacturing processes [69][70]. Group 5: Future Trends - The article emphasizes the ongoing research and development in hybrid bonding and interposer technologies, aiming to achieve tighter connection pitches and improved performance in future semiconductor applications [39][42][73].