Though Intel’s annual Innovation occasion doesn’t kick off till tomorrow, the corporate is already publishing some bulletins forward of the present – and it’s not the trivial stuff, both. This morning the corporate is exhibiting off their preliminary work on growing a glass core substrate and related packaging course of for his or her chips. On account of their progress with analysis and growth on the glass cores, Intel is now planning on introducing glass core substrates to its merchandise within the second half of this decade, permitting them to bundle chips in additional advanced, and finally higher-performing configurations.
There’s loads to unpack from Intel’s comparatively brief announcement, however at a excessive stage, glass core substrates have been below analysis throughout the business for over a decade as a substitute for natural substrates, that are extensively utilized in current-generation processors. Primarily the medium that typical silicon dies sit on, substrates play an essential half in chip packaging. At the beginning, they supply the structural stability for a chip (silicon dies are fairly fragile and flimsy), and they’re additionally the means by means of which alerts from silicon dies are carried, both to different on-package dies (i.e. chiplets), or to the big variety of comparatively sizable pins/pads on the again facet of a chip. And, as chip sizes have elevated over time – and the variety of pins/alerts required by high-end chips has, as effectively – so has the necessity for newer and higher supplies to make use of as a substrate, which is what’s been driving Intel’s newest accomplishment.
In the end, what Intel is aiming to do with glass core substrates is to enhance upon what may be carried out with present natural substrates, permitting for bigger chips with extra alerts to be routed by means of the substrate extra cleanly. And whereas this can doubtlessly have advantages for all chips over an extended sufficient time, the instant focus is on high-end, multi-chiplet processors, the place glass core substrates will provide higher mechanical stability, higher sign integrity, and the power to extra simply route a bigger variety of alerts by means of a non-silicon medium. Briefly, Intel considers it one of many keys to creating high-performance processors within the subsequent decade.
Substrates: A Fast Recap
The necessity for substrates goes again to among the earliest days for large-scale built-in chips, the place chip designs reached 1000’s and tens of 1000’s of transistors. These small transistors wanted to be wired to a lot bigger pins with the intention to be put in in programs by comparatively large human fingers, main as much as the primary chip packages, equivalent to twin in-line packages. These used a body – usually a lead body – to carry the precise silicon die, with the body (or alternatively, wire bonds) offering the sign paths between the die and exterior pins.
Intel 4004 Delidded (Picture Courtesy Science Museum Group Assortment On-line – CC BY-SA 4.0)
Because the 70s, there have been a number of evolutions in substrate designed. Steel frames gave technique to traditional ceramic chip within the 90s, after which natural packaging across the flip of the millennium. Every iteration of substrate had higher properties than the final, above all else, making it simpler to route a bigger variety of sign and energy pins to more and more advanced dies.
When you’ll nonetheless discover lead body and ceramic chips right here and there, natural substrates have been the bread and butter of the business for the final couple of many years. The natural materials, basically made from PCB-like materials layered with woven glass laminates, permits for a pretty big variety of alerts to be routed by means of a chip, together with fundamental chiplet designs equivalent to Intel’s cell processors (with PCH separate PCH and CPU dies) in addition to AMD’s chiplet-based Zen processors.
However natural substrates have already been a limiting issue for a while now, particularly in high-end chips. Which is why during the last decade we’ve seen the rise of ultra-high-density interconnect interfaces equivalent to silicon interposers (chip on wafer on substrate), and their derivatives like Intel’s personal EMIB. These have allowed corporations to bridge collectively the essential paths of their chips with quick and dense items of silicon, however at pretty excessive prices, and with out totally resolving the drawbacks of natural substrates. In consequence, Intel has additionally been trying to find a real substitute for natural substrates, one that can play properly with giant chips, and whereas not changing the necessity for CoWoS/EMIB on the highest stage, would provide higher sign efficiency and denser routing than natural substrates as we speak.
Glass Core Substrates: Finer, But Stronger
This brings us to the subject of as we speak’s announcement from Intel, glass core substrates. The corporate has been engaged on changing natural substrates with glass for over a decade now, and so they’ve lastly reached the purpose of progress the place they’re prepared to indicate it off to the world whereas planning for its use in future merchandise.
At a excessive stage, a glass core substrate is simply that: changing the natural, PCB-like materials of an natural bundle with glass. To make sure, this doesn’t imply changing the total substrate with glass – so Intel is just not going to be mounting chips on pure items of glass – however reasonably, the fabric on the core of the substrate can be made from glass. In the meantime, metallic redistribution layers (RDLs) would nonetheless be current on either side of a chip, offering the precise pathways between varied pads and solder joints.
Glass Core Substrates In Panel Kind
Whereas more durable to work with than the now well-established natural substrate, Intel considers glass substrates to be superior each in mechanical and electrical properties, which in flip makes them fascinating to make use of in future chips. Or, conversely, much less undesirable than natural substrates when constructing very giant chips.
Ranging from the mechanical facet of matter, Intel reviews that cup core substrates provide much better mechanical energy than natural substrates. They’re capable of stand up to greater temperatures higher than natural substrates throughout packaging, leading to much less warping and distortion. Glass can also be reportedly simpler to get flatter as effectively, which makes packaging and lithography simpler. Lastly, glass has an identical coefficient of thermal enlargement as silicon (not like natural substrates), which means that what little warping that also happens from warmth is in line with the dies above, versus having totally different elements of a chip increasing at totally different charges.
Most significantly, maybe, is that each one of these gadgets taken collectively open the door to producing bigger chips. With a extra steady substrate to mount the dies on, it is going to be potential to have bigger dies and a bigger variety of dies all sharing a single substrate – and thus behaving as a single chip.
Bridging the hole between mechanical and electrical, in line with Intel, they’re additionally capable of obtain a a lot tighter pitch on the through-glass vias (TGVs) that carry alerts by means of the substrate itself, permitting for a a lot bigger variety of vias total. Intel is reporting that they’re capable of area TGVs lower than 100 microns (µm) aside, permitting for a 10-fold enchancment in TGV density. All of which finally permits for extra flexibility in routing alerts by means of the substrate core, and to some extent makes it simpler to route alerts with fewer RDL layers.
Assembled Take a look at Chip Substrates
All of this, in flip, permits for not solely bigger chips, however for extra dies to be positioned on a same-sized chip. In line with Intel, glass packaging would enable them to put 50% extra dies on a chip – or reasonably, the die advanced space inside a chip could possibly be 50% bigger – permitting for extra densely packed chips than what Intel can do as we speak.
Lastly, on {the electrical} facet of issues, glass core substrates, and extra particularly the TGVs, reportedly provide higher electrical efficiency as effectively. Owing to the low loss nature of the dielectric utilized in TGVs mixed with the a lot bigger variety of them, Intel says that cup core substrates will enable for cleaner sign routing and energy supply. Within the case of the previous, meaning with the ability to do 448G signaling by means of copper, reasonably than having to make use of optical interconnects. In the meantime, lower-loss energy supply would enhance total chip effectivity by that rather more, by decreasing the quantity of power that’s misplaced as warmth earlier than it even reaches the processor dies.
Farther down the road nonetheless, glass core substrates must also make co-packaged optics simpler to perform for while you do need to use optical. A glass substrate would enable for optical interconnects to be built-in proper into the chip, reasonably than having to tack it on in different manners.
So if glass is so nice, what’s the catch? Whereas Intel is understandably extra excited to speak about what’s good about glass core substrates and what they’ve discovered works effectively up to now, one inescapable ingredient will likely be value. Like several new know-how, glass core substrates will likely be costlier to provide and bundle with than tried and true (and low-cost) natural substrates. And whereas Intel isn’t speaking about yields this far out, it is going to be exhausting for glass to compete with natural, no less than at first.
Extra broadly talking, glass core substrates additionally implies that Intel must bootstrap an entire ecosystem for the fabric. They aren’t vertically built-in with natural substrates as we speak, and so they received’t be vertically built-in with glass, both. To that finish, Intel is already working with companions as we speak to develop the mandatory tooling and provide capability, to convey themselves to preliminary business manufacturing. However over the longer-term, Intel might want to work out the right way to make outsourced testing and meeting potential, particularly as Intel plans to supply glass core substrates to IFS prospects sooner or later.
Lastly, it bears noting that whereas glass core substrates enable for a tighter sign pitch than natural substrates, they aren’t a substitute for EMIB, Foveros, or different extra superior packing methods primarily based round utilizing silicon mediums. A 75µm pitch for a TGV continues to be a far cry from the 45µm pitch of EMIB, by no means thoughts the <10µm pitch deliberate for Foveros Direct. So all of these packaging applied sciences will stay complementary add-ons to glass core substrates, at finest changing EMIB in fringe circumstances of merchandise that don’t want the complete density enhancements of EMIB.
Glass In Motion: Intel’s Absolutely Useful Take a look at Chip
The ultimate a part of as we speak’s announcement from Intel relies across the manufacturing facet of issues. As famous earlier, Intel has been engaged on glass core substrates for over 10 years now, and extra not too long ago has been embarking on a three-and-a-half-year pathfinding undertaking to convey glass core substrates to the subsequent step. Backing these efforts, at this level the corporate has a totally built-in R&D line up and working in certainly one of their Chandler, Arizona fabs (the identical one which does EMIB). Altogether, Intel has spent over a billion {dollars} on glass core R&D up to now.
The primary fruit of their R&D efforts, Intel has accomplished the meeting of a set of check automobiles – multi-chip packages constructed over a glass substrate. The chips, which look much like Intel’s ultra-low energy cell chips (Alder Lake-U 9W?), are reportedly absolutely practical, giving Intel some sensible outcomes to report on. Whereas we don’t have a ton of particulars on the chip, Intel has informed us that it makes use of 3 layers of RDL, and the TGVs have a pitch of 75µm.
Together with proving {the electrical} properties of glass, the small check chip can also be supposed to show among the bodily properties, as effectively. The glass core was made very thick – on the order of 1mm – with the intention to show that TGVs would work with such a thick core. For the type of large, high-end chips Intel is planning on utilizing glass core packing for, these chips would require a really thick core with the intention to hit their measurement objectives, so Intel wanted to show that TGVs would (nonetheless) work at such lengths.
Intel Glass Core Substrates: Coming Later This Decade
Wrapping issues up, as we speak’s announcement serves as a kick-off of kinds for Intel’s glass core substrate period. Following on their decade of R&D work and their pathfinding dash, Intel now believes they’re prepared to start planning for the transition to glass core substrates of their merchandise – albeit a transition that’s nonetheless a number of years out.
If Intel’s product growth goes in line with plan, the corporate intends to start transport glass core merchandise later this decade. The primary merchandise to get the glass core substrate therapy can be their largest and most worthwhile merchandise, equivalent to high-end HPC and AI chips. These are the merchandise most strained by means of natural substrates as we speak as a result of measurement limits these substrates impose, and people are the bounds intel believes would most profit from glass core packaging.
Longer-term, the plan is to waterfall down the know-how from HPC chips into smaller and smaller chips, till the know-how is out there (and viable) for Intel’s rank and file shopper chips. The corporate could be very fast to notice that cup and natural substrates will co-exist for years to return – and, like previous transitions, there’ll probably nonetheless be chips utilizing natural substrates effectively after glass is launched – however the firm can also be optimistic that they’ll have the ability to convey the prices of glass core substrates right down to parity with natural substrates, finally making it potential to reap the advantages even in lower-priced processors.
And Intel received’t be maintaining the know-how to themselves, both. As a part of the corporate’s broader initiative to change into a world class contract foundry, Intel will likely be providing glass core substrates to IFS prospects in due time. Whereas it’s far too early to guess when that will be (even Intel merchandise could also be 6 years out), with the ability to provide glass packaging may give Intel an enormous leg up over its opponents, particularly for producing high-end, highly-profitable chips.
Above all else, it must be reiterated that there’s quite a lot of work Intel nonetheless must do with the intention to convey glass core substrates to the market. But when the corporate is profitable, then the change to glass will usher within the type of main know-how transition that solely occurs each 15 to twenty years.
