> I would assume you could dope in interconnects, between the sides. Actually, you probably can't; the distance between the sides is practically astronomical c

> I would assume you could dope in interconnects, between the sides. Actually, you probably can't; the distance between the sides is practically astronomical compared to the horizontal feature size. I don't remeber the exact actual dimensions, but if you assume a a 1-nm trace is equivalent to a 10-meter road, then a 1-mm wafer thickness would be equivalent a 10'000-km planetary diameter, so you're getting close to the scale of routing a internet cable through the center of the earth. (At least it's not molten, I guess?) And doping generally works by diffusion, not drilling a hole.