Intel started the race, Samsung joined in, and TSMC waited for the ideal time to form a three-horse race.

In the advanced packaging industry, the innovation race has reached a new critical juncture with the advent of glass-core substrates, which Intel announced in September 2023. This new technology direction comes on the heels of the wave of organic and ceramic substrates, promising to overcome the challenge of a core substrate to take performance, efficiency, and scalability to new levels in terms of chip design and manufacturing costs, thus following the megatrends of HPC and AI. The latter depends on the maturity of the technology and its wide application in the end market.

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As a material, glass has been extensively studied and integrated in multiple semiconductor industries. It represents a significant advance in the selection of advanced packaging materials and offers several advantages over organic and ceramic materials. Unlike organic substrates, which have been the dominant technology for many years, glass has excellent dimensional stability, thermal conductivity and electrical properties.

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However, despite the potential benefits, as with any new technology, glass-core substrates face a host of challenges, not only for substrate manufacturers, but also for equipment, materials and inspection tool suppliers.

Bilal Hashimi, semiconductor packaging technology and market analyst at Yole Group, said that the fragile nature of glass poses problems for the internal handling and processing of the equipment, which is not suitable for the glass fragments generated when the glass is broken, so great care and precision are required in the manufacturing process. This is an expensive challenge for equipment suppliers and substrate manufacturers. In addition, glass substrates introduce complexity to the inspection and metrology process, requiring specialized equipment and technology to ensure quality and reliability.

Despite these challenges, the adoption of glass-core substrates is being driven by several key factors. The need for larger substrates and form factors, coupled with technology trends in chips and heterogeneous integration, is driving the industry to look at glass as a potential solution. In addition, once the technology matures and is widely adopted, the potential cost benefits of glass will make it an attractive option for the high performance computing (HPC) and data center markets.

Since last September, Intel's pioneering efforts to support glass-core substrates have laid the foundation for industry-wide adoption. After a decade of research and development effort and investment, and 600 patents related to GCS, Intel's announcement of its plan to select a glass substrate provides guidance and direction to the industry, encouraging other players to explore this promising technology. Just a few months later, Samsung's entry into glass substrate production marked another milestone in the history of this emerging technology, underscoring the impact of Intel's initiatives, growing interest and investment in the technology. In parallel with Intel's efforts, Absolics received its first major investment of $600 million funded by SKC, marking the continued development of GCS. The investment means Absolics is the first company to focus exclusively on producing glass-core substrates, just with a different technology from Intel.

In addition, the emergence of new companies such as Absolics and SCHMID, as well as the participation of laser equipment suppliers, display manufacturers, chemical suppliers and others, highlights the diverse ecosystem formed around the emerging supply chain of glass core substrates. Collaborations and partnerships are being established to address the technical and logistical challenges associated with glass substrate manufacturing, demonstrating that all parties are working together to realize its full potential.

In this field, the glass through hole (TGV) is one of the pillars of the glass core substrate. The TGV paves the way for more compact and powerful devices. TGV helps to increase the density of interlayer connections. These through-holes help improve signal integrity in high-speed circuits. The reduced distance between connections reduces signal loss and interference, thereby improving overall performance. The integration of TGV can simplify the manufacturing process by eliminating the need for a separate interconnect layer. However, despite its many advantages, the TGV also faces many challenges. Due to the complexity of the manufacturing process, TGVS are more prone to defects that can cause product failure.

In addition, TGV usually means higher production costs than other solutions. The need for specialized equipment coupled with the risk of defects may lead to increased production expenses. Recently, many new TGV-related patents have been granted to laser equipment manufacturers such as LPKF. These advances help commercialize glass-core substrates while addressing the challenges associated with glass intermediate layers. The solution enhances the GCS and Glass intermediary layers, offering hope for an exciting next generation of powerful devices.

In addition, synergies between glass-core substrates and panel level packaging (PLP) are driving innovation in both areas. Since both technologies employ similar panel sizes, they offer complementary opportunities to increase chip density, reduce costs, and improve manufacturing efficiency.

Glass-core substrates represent a promising frontier in advanced IC substrates and advanced packaging. They offer unmatched performance and scalability for the next generation of chip design and packaging. While challenges remain - as is the case with all new technologies - the combined efforts of industry leaders and new entrants are paving the way for the widespread adoption of glass substrates across various end markets, with AI chips and servers as a focus. As GCS technology matures and supply chain infrastructure evolves, glass-core substrates are expected to redefine the landscape of advanced packaging.