3D stacked integrated circuits are on the roadmaps of most logic, flash and DRAM vendors today. In 10 years time, we will have seen widespread adoption of this technology. Shouldn’t we know who invented or talked about 3D Stacking first? After all, this technology is going to have a huge impact on our lives…
Moving on to Early and his “early” paper on 3D… (I know, I know. The last line is a bad attempt at humor, but I couldn’t resist the pun!) What is Jim Early famous for? In school, most of us Electrical Engineers learnt about the “Early effect” in bipolar transistors, where the base width reduces when collector-to-base voltage is increased. Yes, this effect is indeed named after Jim Early, he discovered it first. Jim Early did that work when he was at Bell Labs in the 1950s. He moved to Fairchild Semiconductor in 1969 as VP of R&D after Gordon Moore, Bob Noyce and Andy Grove left Fairchild to start Intel. Moving on to Early’s paper at the 1960 ISSCC, you can see a summary of it in the figure above. In the paper, Early talked about how components would ideally be arranged in a 3 dimensional cube to form circuits. Incredibly, he also talked about how heat removal would limit the number of components that could be placed in the cube.
It’s been 50 years since Early’s paper, and we are starting to see the first 3D integrated circuits come out. 3D has been a long time coming, hasn’t it?