The Critical Role of Inspection and Metrology in Silicon Photonics Manufacturing

Abstract

The rapid growth of artificial intelligence (AI) workloads is increasingly constrained not by transistor scaling, but by interconnect limitations across package, die, and system levels. Electrical interconnects are emerging as a primary bottleneck, restricting achievable data rates, increasing latency, and driving unsustainable power dissipation and thermal load. As a result, advanced packaging architectures are being fundamentally reshaped around interconnect innovation. 

Approaches such as 2.5D and 3D integration, heterogeneous integration, chiplet architectures, and high-bandwidth memory (HBM) improve proximity between compute and memory, but further exacerbate interconnect density, signal integrity, and die/package heat challenges. Silicon photonics (SiPh) is rapidly gaining adoption as a scalable solution, enabling optical interconnects that deliver significantly higher bandwidth density, lower latency, and reduced energy per bit compared to traditional electrical I/O. Technologies such as co-packaged optics are emerging as critical enablers to overcome interconnect-driven system constraints in next-generation AI infrastructure. 

However, SiPh integration introduces process control challenges across key device structures, including waveguides, microlenses, laser and photo-diode fabrication, fiber connect v-grooves, and integrated heaters. Performance is highly sensitive to film thickness, refractive index, sidewall geometry, stress, and material uniformity. As a result, advanced films metrology and inspection play a central role in enabling manufacturability. Techniques such as spectroscopic ellipsometry, picosecond acoustics, and high-resolution inspection are essential for controlling critical dimensions, material properties, and defectivity across these structures. 

This presentation highlights detailed examples of where inspection and metrology provide truly unique capabilities supporting optical device performance and integration in this high growth sector enabling process control, yield, and reliability for high-volume manufacturing of silicon photonics-based interconnect architectures.