I've heard a rumour too that there's a safe in each of their fabs containing enough explosives and instructions on how to scuttle the fab in case of invasion.
This would not surprise me, especially considering just how little you would need to catastrophically disable one of these factories. That said, I don't think this is a very practicable angle to worry about, since it's not just the factory you need to make the products. It's also the people, experience, and massive logistical octopus the factory is hooked into that makes it able to produce these incredibly valuable products. One minor deviation in a supply chain (i.e. a vendor switch) can mean millions of dollars in scrapped wafers. Just having the factory and its tools doesn't mean anything for an invader. It would simply become the most expensive waste of space on the planet.
Not much actually (I've worked in a fab), the entire floor is porous to allow air through it and fab HVAC systems attempt to create laminar flow from top to bottom [1].
That is seriously cool. Does that reduce the need for protective equipment to keep dander and dust from getting everywhere or is this strictly in addition? My sense of how destructive dust can be in these facilities may be inflated. I'd heard that re-establishing a clean room can be a huge PITA and the first thing I could think of was powders getting in there.
If you're ordering your people to destroy equipment, you could turn off the air handlers first, right? You're not gonna be in there long enough for the CO2 to build up to harmful levels. Unfortunately I don't recognize most of those acronyms. Are they dealing with fumes as well?
No, its in addition. There are micro-clean environments inside the tools themselves. The wafer chamber is a couple of orders of magnitude clean. The plastic box that carries 15-20 wafers has to be specially made for cleanliness, each piece costing thousands of dollars. Entegris makes these boxes too [1].
It honestly depends on where in the fab. One of the most dangerous things from a chemical perspective would be copper in the non-copper part of the factory. If you set off something jacketed with copper right in the middle of the photolithography tool area, it would probably be game over for quite some time.
Given we're in a hypothetical about 'how would you scuttle your own fab', and that I'm verbalizing the implicit "without hurting any employees", I'd guess that one or several team leads in charge of either automation design or maintenance could think of a dozen nightmare scenarios or even personal anecdotes of proverbial wires getting crossed and causing mayhem. If the solvent got into this line, or the effluent into this one, or the wrong voltage here, or the part installed backward here (because in The Expanse they don't have keyed sockets to prevent an employee from installing high current equipment backward, apparently... but I digress).
We tend to be limited in our creativity, though. You mentioned a pretty violent way to distribute copper, isn't powdered copper a common ingredient in fireworks? You just need to get the copper airborne, unattended (copper poisoning I hear is pretty awful), not make a big boom. You would have absolutely no cause to have that material anywhere near let alone inside of a fab. But if a hostile takeover at gunpoint is actually a scenario you're concerned about instead of a bunch of randos bullshitting on the Internet? Wouldn't be hard to prepare some boxes and a laminated instruction sheet to put in a safe somewhere. In Case of Armed Invasion, Read Instructions.
That would be far too dangerous as this makes future construction work on a building extremely risky. I don't believe that for a second. I would not be surprised of there's a plan for the sabotage of infrastructure or valuable facilities in general.
In a similar vein, German roads and bridges had shafts in them for explosive charges. The plan was to blow them up in case of a Warsaw Pact invasion to slow any enemy advance.
