AMD 3D V-Cache teardown reveals almost all the Ryzen 7 9800X3D is dummy silicon
It has been over a month since AMD launched its Ryzen 7 9800X3D processor which quickly established itself as a result of the quickest gaming CPU on the planet. To investigate AMD’s design philosophy, semiconductor analyst Tom Wassick (by means of Hardwareluxx) took apart the chip, and the findings of his first report counsel {that a} massive part of the Ryzen 7 9800X3D is just dummy silicon for structural integrity. Nonetheless, AMD has extracted various effectivity from its second-generation 3D V-Cache design, landing a powerful victory in the direction of Intel’s Arrow Lake chips.
Ryzen 9000 X3D processors are structured to suit the L3 SRAM cache chiplet beneath the heat-generating CCD (the compute die with the eight CPU cores). This allows for bigger clock speeds by offering further thermal headroom, though AMD in no way exactly detailed the ins and outs of its stacking methodology. The report mentions that every the CCD and 3D V-Cache chiplets are thinned proper all the way down to sub 10µm ranges to disclose the TSVs for hybrid bonding. Coupled with BEOL (Once more-end of Line) – the half with the necessary metallic layers for connectivity – the general SRAM and CCD bundle deal is out there in at 40-45µm thick.
The SRAM die has on a regular basis been a fraction of the scale of the compute die; Ryzen 7000 3D V-Cache chiplets measured 36mm-squared in distinction to the 66.3mm-squared CCD. Tom Wassick’s findings state that the SRAM die is unquestionably 50µm greater than the CCD on all 4 sides. Realistically speaking, a giant portion of this die must be empty, nonetheless we nonetheless await further particulars.
Excluding interconnects, the SRAM and CCD ought so as to add as a lot as decrease than 20µm thick. To accommodate such small and fragile parts, AMD has added a cumbersome layer of dummy silicon on the prime and the underside for structural integrity. The thickness of all of the bundle deal is roughly inside the ballpark of 800µm. Subtracting the 50µm die stack (CCD, SRAM, and BEOL) lands us at 750µm of structural help on the prime. In several phrases, 93% of the general stack contains merely dummy Silicon to keep up the dies intact.
The utterly totally different layers are associated by means of a coating of oxide between them. It is reported that this binding layer is thinner between the core CCD and SRAM than between the dummy silicon and the two dies, to allow for increased thermal effectivity.
There keep a variety of unanswered questions and Tom Wassick plans to take care of them with the help of a Scanning Electron Microscope in a future follow-up. No matter dropping its gaming throne to AMD, Intel has no plans to counter AMD’s 3D V-Cache experience, at least for the mainstream part. Nonetheless, we anticipate AMD to announce the 12-core and 16-core Ryzen 9 9900X3D and the Ryzen 9 9950X3D at CES subsequent month.
