Over the last few years Intel has made important progress at the level of packaging with the specific intent of overcoming the classic limits of silicon and traditional designs. Now Intel is focusing on glass to face the challenges of the decades to come.
For the design and production of electronic chips and in particular in processors, an organic substrate is used. Adopted since 1995, it is a thin structure, often made of a material similar to a printed circuit board (PCB), which acts as a mechanical support for the electronic chip, known as die.
Il organic substrate performs several very important functions: for example, it ensures mechanical stability for the chip (i die silicon are fragile and weak), the transfer of signals and electrical power between the chip and other electronic components, such as chiplets, or between the chip and the pins or “pads” on the back of the chip itself.
The solution adopted so far, which has lasted thirty years now, is low cost and easy to produce but has a series of important shortcomings. They began to be noticed for some time and now they are starting to slow down the development and progress of the design and production of chip heterogenei high-power, with multiple chiplets and blocks stacked in both two and three dimensions.
When it comes to assisting the operation of larger and more complex chips, the organic substrate can highlight problems heat dissipationelectrical interference, and density limitations for signal routing.
Why Intel chose to switch to a glass substrate for its chips
Intel is focusing on glass (the technology is referred to as Next Gen Substrate, Glass Panel Intel) as an alternative to organic substrates because glass offers a number of advantages in terms of stability, performance and capacity. An innovative solution of this type provides the opportunity to support the design of high-end processors and other advanced applications in the semiconductor industry.
The company led by Pat Gelsinger has been working on the transition for some time, but it promises to be quite complex. So much so that there will be a long period in which products based on the organic substrate and products built on a glass substrate will coexist on the market and among end users.
Glass, however, offers different advantages including greater mechanical stability compared to organic substrates; better electrical performance; allows for greater density; endure temperature elevate during the encapsulation process; makes it easier to integrate optical components within the chip.
Over the last decade we have witnessed the spread of interconnection interfaces ultra-high density like the interpose in silicon and derived solutions such as Intel EMIB. These schemes have allowed companies to connect the critical paths of their chips together with fast, dense “chunks” of silicon, but at quite high costs and without completely solving the problems of organic substrates.
As a result, Intel has identified the real alternative in glass substrate on which he has been working for about 10 years now and which now seems ready for its grand debut.
Through-Glass Vias (TGV): what they are and what it means to reduce the distance between communication routes
The Through-Glass Vias (TGV) are passages or holes drilled through the substrate, used to route electrical signals from one part of the substrate to another. These holes or vias allow the connection of electronic components mounted on opposite sides of the substrate, allowing the transmission of electrical signals between them.
By acting as a bridge between mechanical and electrical, according to Intel, the glass substrate allows bring the streets closer together (TGV) reducing the pitch to the minimum terms. Intel claims it can space TGVs to less than 100 microns (µm), enabling a 10x improvement in density.
Intel is focusing on glass even though it is an expensive technology
While Intel is naturally more keen to talk about the benefits of adopting the glass substrate, the cost it will be a decidedly limiting factor. At least in the initial stages.
The central glass substrates will be more expensive to produce and package compared to well-proven (and economical) organic substrates. And while Intel isn’t talking about large-scale adoption of the new technology anytime soon, a sustained migration will take some time.
It is also worth highlighting that although glass substrates allow a pitch reduced, they are not yet a substitute for EMIB, Foveros or other techniques packaging. And pitch of 75 µm for a TGV is still a long way from pitch of 45 µm of the EMIB; imagine if this value is compared with the pitch lower than 10 µm of Foveros Direct. All the various technologies of packaging they will remain complementary to the glass substrates.
EMIB, Foveros and Foveros Direct in breve
EMIB is the acronym for “Embedded Multi-Die Interconnect Bridge“: it’s a interconnection technology advanced developed by Intel to connect multiple chips together or die within a single electronic package or module. The idea behind EMIB is to create a bridge between chips or chiplets using an advanced substrate that offers high electrical performance. This way you can get a fast communication and reliable between the various components within the package.
Foveros and Foveros Direct are technologies 3D stacking advanced technologies developed by Intel: allow you to create more compact and powerful electronic devices by vertically stacking several layers. Foveros allows you to create thinner and more compact devices: chips can be stacked vertically rather than arranged horizontally on a motherboard. Already with processors Intel Core of tenth generation, CPU, GPU and other components are stacked.
Foveros Direct is a further evolution designed to improve performance and integration density: the chips can be connected directly and, as explained previously, the connection density of signals is significantly superior to the traditional Foveros approach. The advantages are, of course, the greatest integration of electronic components and better heat management.
Foveros Direct technology is designed for high-end applications, such as high-performance computing (HPC) and artificial intelligence (AI) devices, where fast communication between chips is essential.
Glass substrate to debut in first commercial products by 2030
The first products to receive glass substrates would be the largest and most profitable ones, such as chip HPC (High Performance Computing) high-end and those dedicated to artificial intelligence: they will debut by 2030.
Intel, however, won’t keep the technology to itself. As part of the company’s broader initiative to become a partner of choice for the purpose of creation of chips for third partiesthe company will offer the use of the glass substrate under the IFS program (Intel Foundry Services).
The images in the article are from Intel and are taken from the Intel Unveils Industry-Leading Glass Substrates to Meet Demand for More Powerful Compute release, September 2023.