Glass Core Substrates: Driving Scalability for HVM Through A Versatile Process Control Solution

By Monita Pau

Abstract

Heterogeneous integration packaging technologies have seen increased adoption driven by the rapidly growing demand for advanced end applications like artificial intelligence (AI) and high-performance computing (HPC). Research and development of glass core substrates are gaining momentum to address the increasing I/O density, bandwidth and functionality demand due to their superior mechanical stability and ability to enable the fabrication of high-density interconnects. However, due to the brittle and rigid nature of glass, their adoption also poses significant manufacturing challenges. Stringent process control is required starting from the bare glass panel and throughout the entire glass core fabrication and buildup process to ensure high manufacturing yield and product reliability.

In this presentation, we will explore the manufacturing challenges in glass core substrates. We will present the integration of a high throughput and multifunctional process control solution starting from the fabrication of through glass vias (TGV) in the glass core. Real-time process control of the laser modification and wet etching process is made possible through the ability to inspect and perform CD measurements across the 100% of the panel surface. Besides CD monitoring, we will also demonstrate the ability to detect missing and abnormal TGV as these defects can directly impact the electrical performance of the product. Glass is brittle and prone to cracking or chipping during handling and processing. Microcrack detection before and after metallization is crucial to help detect the mechanical damage early to avoid for downstream yield loss.

With its unique integrated metrology and inspection capability, the same in-line process control solution can also be applied throughout the buildup process. From monitoring the defectivity and CD of the traces post-patterning and metallization, to the 3D measurement of RDL/bump height and panel warpage. This enables for real-time response to variations in material, equipment and process conditions and ensure high productivity and manufacturing yield.

To realize the full benefits of glass as a core material for advanced IC substrate, an advanced inspection and metrology solution is vital to provide the industry a scalable path to bring glass core substrate from research and development to high volume manufacturing by the end of this decade.