Today's report is a background brief on the trend of 3D chip stacking technology and the coming revolutionary switch  to glass substrates for chips between 2026 and 2030.

Apple's 3D chip stacking technology SoIC will reportedly be used in a 2025 MacBook (Pro). In simple terms, it is a new type of IC packaging technology that can stack multiple chips together to achieve higher integration with smaller size.

For consumers, this revolutionary MacBook will bring more choices/features. With the development of 3D stacking technology, we can see that more electronic products will be adopting it, from mobile phones, tablets to TVs, set-top-boxes, cars, and other smart home smart devices. Apple will be using TSMC's 3D Fabric technology

Three-dimensional integrated circuit (3D-IC) is a die-stacking technology used in semiconductor packaging that offers new levels of efficiency, power, performance, and form-factor advantages to the semiconductor industry. 3D-IC is built by wafer-on-wafer or chip-on-wafer stacking on a single package interconnected using through-silicon vias (TSVs).

3D-ICs with TSVs are expected to broadly impact networking, graphics, mobile communications, and computing, especially for applications that require small, ultra-light, low-power devices. Specific application areas include multi-core CPUs, GPUs, packet buffers/routers, smartphones, tablets, netbooks, cameras, DVD players, and set-top boxes.

The industry is quickly moving to Glass substrates to replace today's 2.5D and 3D packaging technology. On the surface, the media in general has focused on AMD, Intel and Samsung being the leaders racing to deliver glass substrates for chips with little to no coverage on TSMC's position. One source noted that "Industry analysts have noted that TSMC also has similar solutions." While this isn't exactly proof that TSMC is pursuing this, TSMC's chip leadership would strongly suggest that they're working on this and keeping it under wraps at the moment. There's no chance of TSMC being out of the loop on this revolutionary development.

In the interim, TSMC is first exploring a switch to rectangular chip substrates. According to a TechSpot report published on June 21, 2024 "TSMC is venturing into uncharted territory with a novel approach to advanced chip packaging. The chipmaker reportedly plans to switch from conventional round wafers to rectangular substrates, allowing significantly more chips to be placed on each wafer.

The proposed rectangular substrate is currently undergoing trials. Measuring a substantial 510mm by 515mm, it reportedly boasts over three times the usable area of current round wafers. Additionally, the rectangular shape reduces wasted space around the edges. The study is still in the early stages, and its results may take a few years to reach the market.

Historically, substrates have been round due to their handling advantages and superior strength. However, the sudden interest in changing this trend is unsurprising given the AI boom. Like other chipmakers, TSMC is feeling the pressure from the skyrocketing demand for computing power and aims to keep pace.

TSMC is not the only manufacturer experimenting with cutting-edge substrate technologies. Its biggest competitor, Samsung, is rumored to be investing heavily in research and development of glass substrates for chip manufacturing, with the goal of bringing products to market as early as 2026. Using glass offers several advantages compared to organic substrates, such as enhanced flatness, which improves the depth of focus for lithographic processes.

It's a race to bring chips on glass substrates to market. Intel has also pledged to bring this to market between later in this decade.  Taiwan's "Business Next" publication points to Intel's plan unfolding between 2026 and 2030.

The U.S. government awarded Absolics, an affiliate of Korea’s SKC, $75 million under the U.S. CHIPS Act to build a 120,000 square-foot facility in Georgia to make glass substrates. You could read more on Absolics Gorgia' plant working on Glass Substrates here.

“The benefits of glass are clear,” says Rahul Manepalli, fellow and director of substrate TD module engineering at Intel. “But the problems that you have to solve include interface stresses, understanding fracture dynamics of glass, and understanding how to decouple stress from one layer to another.”

While industry leaders are working on future glass substrates for future 3D chip fabrication, there are still many hurdles to overcome and you could read about the pros and cons using glass in an article from Semiconductor Engineering.

AMD is now in the news in a new article titled "AMD is reportedly set to use glass substrates for CPUs between 2025 and 2026," according to Business Korea.

Apple reportedly bringing 3D chip stacking technology SoIC to MacBooks in 2025 opens a new a trend that is only going to greatly expand over the next five years as major industry players AMD, Samsung, Intel and likely TSMC shift to using glass substrates.  

For those interested in this coming trend, you could read more about it in the following reports:

01: What is 3D Stacking Technology in Electronics?

02: 3D-IC Technology

03: Glass Substrates in Advanced Packaging With Intel Leads, TSMC Quietly Innovates

04: Glass substrates to replace 2.5D package in chips in the future