Intel Develops Glass Substrate for Next Gen Advanced Chip Packaging Needs
Intel has unveiled new glass substrate technology for large chiplet based system-in-package chips. Glass substrates allow for denser packing of chiplets—an important for applications like AI and others.
As any engineer knows, ICs are much more than just silicon. The sundry components—such as the packaging, leads, and substrate—all factor into the durability and ultimate capability of the component. Increasingly, the substrate—the material the silicon IC wafer is mounted on—is playing a significant role in allowing for more computing power in one package.
Feeding those needs, Intel has announced a new glass-substrate technology for the next generation of high-power processors.
Glass substrate system-in-package prototypes
Glass as a substrate is not a new concept. For nearly a decade now, the very smallest of chips, wafer level chip scale (WLCS) components have used a glass substrate. In this form factor, the BGA (ball grid array) solder balls are mounted directly on the IC wafer, which is then mounted circuitry-side down in flip-chip style with a protective glass substrate on the topside.
Some of the more common chips to use this package system are power components such as voltage regulators and converters. The smallest of these parts are only a few millimeters square and yet can handle the same power as a large TO-220 form factor due to the more direct thermal path through the solder balls and the glass substrate as a heat spreader.
Glass as a substrate has many advantages over more conventional materials, both in the manufacturing phase and in the end application. Now, Intel is looking to bring those thermal properties and other improved substrate characteristics to its largest chips with a newly developed large glass substrate technology.
Features That Allow for Denser Chiplet Interconnects
Many of the new, highest performing chips are developed using multiple chiplets, rather than as a single monolithic piece of silicon. This is called system-in-package architecture, or disaggregated design. Doing so allows for higher yields, greater manufacturing flexibility and greater computing power in the same physical space.
All that said, current organic substrates—similar to a high temperature printed circuit board (PCB)—are not stable enough for the manufacturing process and operational temperatures encountered.
The organic substrate may warp or degrade with the higher temperatures. Essentially, the organic substrates are running up against their size limits. Glass is capable of withstanding the higher temperatures without warping or degrading. This allows for denser spacing, with 50% more chiplets in the same package area.
Glass substrate allows for 50% more chiplets.
Meanwhile, these chiplets need high speed interconnects in order to function as a single unit. Glass has a smoother surface than the organic materials and has thermal expansion properties that are much closer to the silicon wafer.
The smoother glass surface will enable tighter design rules (smaller trace and space) for the interconnects. Glass with its greater stability at higher maximum working temperature allows for 50% less lithography pattern distortion. The end result is a 10× improvement in interconnect density.
Ponte Vecchio data center AI processor with 47 different chiplets
Heat removal from high power CPUs for AI and data center applications is one of the major areas of power consumption in server farms. It also limits the processing speed of large monolithic chips.
Moving to a chiplet layout allows for a thermal gap between sections of the processor. The space can also be utilized for more efficient power delivery to individual subsections. Both of those advantages allow for higher speeds and lower power consumption.
Trickle Down to Mainstream Applications
Applications for chiplet-based ICs go far beyond data center and high-end applications. Intel’s newest Meteor Lake laptop CPU is built with chiplets to offload power hungry functionality from the CPU. It has a multi section (called tiles by Intel) architecture, grouping chiplets for low power work, high power compute intensive work and graphics.
Meteor Lake doesn’t use a glass substrate, but it uses the chiplet architecture that in future processors will benefit greatly from the new glass substrate technology.
With more chiplets, better power delivery and higher speed interconnects, Intel believes that the reductions in power consumption and improvements in density will result in the ability to put one trillion transistors in a package by the turn of the decade. Intel is banking on this capability to benefit both their own IC manufacturing and their foundry service business.
All images used courtesy of of Intel