As semiconductor assembly and test services provider ASE Global said in its discussion of heterogeneous integration (HI), the semiconductor industry is facing a new era in terms of device scaling and cost reduction. Packing more transistors onto a monolithic IC is becoming increasingly difficult and expensive at each node; semiconductor companies are seeking technology solutions to bridge the gap and improve cost-performance, while at the same time adding more functionality through integration.
The system-on-a-chip (SoC) approach, which integrates all functions into a single chip, is well-traveled — but it also presents many challenges, including higher costs and design complexities. Heterogeneous integration represents another alternative: It integrates multiple dies into the same into a higher-level system-in-package (SiP) assembly, enabling the package to perform a specific advanced function in a small form factor.
Onto Innovation said the HI roadmap for advanced integrated circuit substrates (AICS) is rapidly approaching several new demarcation points. These include challenges for organic substrate redistribution layers (RDLs) using copper clad laminate (CCL) below 3 µm, which are prompting manufacturers to adopt more stable substrates such as glass. The need for handling both large glass core panels along with existing, mature CCL-based organic substrates creates a need for new lithography tools capable of handling both substrate types.
Onto’s solution is a new glass substrate suite comprised of two parts: the JetStep X500 panel-level packaging lithography system, offering hybrid substrate handling capabilities; and the Firefly G3 submicron automatic metrology and inspection system for panel-level packaging and AICS. Together, the two components represent a complete panel-level packaging solution supporting HI chiplet packages for AI, high-performance compute and cloud computing.
The JetStep X500 is optimized for volume manufacturing of high-end AICS and advanced packaging panels and, according to Onto, incorporates the industry's largest field exposure system. Features include fine-line redistribution layer (RDL) resolution with large depth of focus (DOF), high overlay accuracy, automatic magnification compensation with independent x and y magnification adjustment, and the ability to handle a large range of substrate thicknesses with high levels of warp.
The Firefly G3 (which Electronics360 wrote about shortly after its introduction) addresses process control challenges inherent to glass substrate production, through glass via (TGV) formation and the copper plating process. The same illumination techniques used by the Firefly G3 for inspecting organic panels can be applied to glass panels as well. The system can identify cracks and chips caused by handling, perform TGV metrology for vias and inspect for defects like dimples formed during etching. The system’s 3D metrology sensors enable users to achieve proper copper plating height uniformity for RDLs.
Combined, the two systems represent a powerful solution as the industry pursues a glass core panel transition — and another journey along the evolving HI roadmap.
