In this case, this could either be through a coop (e.g. those factories are directly owned by the workers working in them, decisions are made democratically) or through a worker's state (the factories are owned by the state as a representation of the workers - this is what the USSR tried to do, but failed miserably at).
I think any other scenario has people leeching off the work of the folks actually producing those semiconductors - e.g. exploitation.
Index funds don't do anything to help this - just cause it's a bigger group of strangers stealing the products of the worker's labor doesn't make it any less exploitative.
And nobody's saying we should tear down the factory, we just shouldn't let it be owned by people who have nothing to do with the work being done so they can make money from nothing but the fact they had money already.