I work at as a process engineer.

about semiconductor processing.

(I will not be answering questions about CPU design specifically, but about semiconductor processing in general)

How exponentially does Economies of Scale have to size up for transistor densities smaller than say, 32 or 64 nanometers over even 14 or 12?

@HarneyBA node sizes are determined such that each node size decrease translates to a doubling of transistor density.

Ie for planar transistors, the drop from 45nm to 32nm doubled the number of transistors per square millimeter.

Of course, the cost of each node drop is greater than the gain in transistor density

@HarneyBA that doesn't hold up anymore, however, in the era of FinFET transistors. Intel has been FinFET since 22nm, and pretty much every node smaller than that in the industry is also FinFET.

Node size in FinFET era is also mostly meaningless below 15nm, because it doesn't account for fin pitch and density in any way

@HarneyBA cost goes up a huge amount from this point forward. Below 10nm it requires new UV technology that is only just now coming to fruition.

450mm wafers are also just around the corner, and when they are ready, the ENTIRE industry will move to them at the same time. That will require ENORMOUS capital expense the likes we haven't seen since 300mm wafers came out

@matt @HarneyBA By around the corner how soon could we see 450mm wafer chips in consumer devices? 1yr? 3yrs? 10yrs?

Also for 3D chips my understanding is that they separate the "layers" with a glass like substance? If they were to only create two layers and pull heat from either side would that solve the thermal issue while still allowing for shorter connections? Obviously I'm no where near qualified to even ask the question properly so pardon my ignorance.

@AtypicalKernel @HarneyBA 3d chips are the future.

Here's the thing about chips and heat dissipation. Think of it like cooking a turkey. The outside of the turkey is VERY easy to cook and cook rapidly, but the core of the turkey takes hours. This is because of the thermal properties of turkey meat.

When cooling something, the opposite is also true. Those very same properties that make heating a turkey slow, also make cooling the inside of a turkey slow.


@AtypicalKernel @HarneyBA Applying that to 3d chips, once you start dealing with a chip that is an order of magnitude thicker than before, the very center of the chip will be very hard to keep thermally regulated.

The very same properties in materials you want for electrical insulation also, unfortunately, translate into heat insulation. They are intrinsically the same property, and I'm not aware of many materials that are great heat conductors and poor electrical conductors at the same time.

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