we have been in various ways for a long time. as you stack higher and higher it gets harder to get the heat out, and its already really tough to get the heat out.

Like intel's fastest gaming processor, the 9900k, the major difference is better heat dissipation material between the die and heat spreader.

laptops and phones are mostly all thermally limited

die shrinks help with this, but only if you don't increase performance as you do it.

It is used. 3d stacking is called.

Most memory devices, like pendrives use that.

Heat dissipation is the killer