In fairness, this is a horrifically complex subject. Pretty much every point you mention is a rabbit hole that you can spend ages exploring. e.g. the metal sta

In fairness, this is a horrifically complex subject. Pretty much every point you mention is a rabbit hole that you can spend ages exploring. e.g. the metal stack: One would like to connect transistors together. Copper is lower resistance than doped silicon, so we'd prefer to use copper. But there's a catch: copper diffuses into silicon. That is, if you attempt to directly plate copper onto silicon, some of the copper diffuses into the silicon crystal mucking up all the careful doping of the silicon we just did. So we put down a barrier layer first: We first coat the silicon with tantalum nitride which has significantly lower diffusion rates into silicon. And then we put copper on. No! Wait! We can't put copper directly onto tantalum nitride for <complex reasons this margin is too small to contain>. So we put tantalum metal onto the nitride,and then we put copper onto that metal. This is the sort of thing that referred to as a metal stack. I've hand-waved like crazy here. The actual metal stacks are way more complex than this. The article alludes to some of the recent challenges: The tantalum nitride barrier layer is too thick so there's a move to replacing it with a cobalt based stack, or maybe even a manganese/ruthenium based stack. The author had a pretty tough job in trying to explain some of what's going on to a lay audience and (likely) do it inside a word limit. We can argue about successful it was on the margins, but personally I'm still very appreciative that they tried :)