Effectively it is an atmospheric interaction, most commonly with oxygen but also light, hydrogen sulfide (from agricultural production - land is cheaper in the countryside), and other sources of contamination.
Most wafer processing - especially depositions of materials like metals - are done in a vacuum. if you deposit a metal (lets assume aluminum) in a vacuum you effectively get a pure aluminum layer. Pure aluminum is highly reactive with oxygen
As soon as that layer is exposed air it oxidizes - same thing as rust. You know this as the dull surface finish that raw/bare aluminum gets if left out or when you purchase it. It's what happens very quickly after you machine aluminum - the shiny surface goes away. That is the aluminum oxidizing.
Aluminum oxide has different electrical properties than pure aluminum, different enough to fundamentally affect the function of the transistor devices being constructed. If I have a 2" thick piece of aluminum that layer, maybe only a few microns (assume 5) thick after 24 hours, is basically inconsequential. It represents 0.01% of the thickness of the piece. It is error but not much more in the electrical properties of the piece. However, if semiconductor layer is much thinner... maybe 10microns thick...the effect of the oxidation on the electrical properties is much much higher and pushes it outside the tolerances the device can have and still function.
And because the deposition layers aren't just surfaces, but penetrate to fill trenches in the devices they are basically impossible to remove at most steps.
Edit to add a few more details:
A vacuum capable FOUP would be much MUCH heavier, requiring retorfitting of the overhead vehicles that transport wafers aroudn the FAB. further, each FOUP carries 25 wafers. A FAB can easily put out 30k wafers a week...it's a lot of FOUPS. even if you just used them at critical steps it would get heavy and expensive. I believe there was some talk abotu inert gas purges with the move to 450mm wafers but, like 450mm wafers, that never happened.
These events have been shown to be very rare, and the costs would greatly outweigh the benefits (for the time being).
The cheapest piece of equipment was the stand the FOUPS come down and rest on. From memory, that was easily 5 figures, perhaps low 6. Every other piece of processing equipment was insanely more expensive.
Queuing theory is an active field of research with great applications in how wafer processing. The total process has to be looked at. Wafer priority, wafer value, planning preventative maintenance on the machines, etc. could all be taken into consideration when scheduling when wafers will run.
Retrofitting every "robot" that grabs FOUPS for a much heavier load, upgrading the tracks if needed, replacing every single FOUP, adjusting factory flow and inventory holding areas, doing qualifying trials on the FOUPS (to make sure they're functioning correctly and not leaking), etc. are considerable expense.
Prioritization of wafers and timing the preceding step so the required machine is certain to be ready in the window would yield better results from a strict business ROI perspective.
Yes. And I was responding to georgeburdell's comment about long-term losses from this virus infection. In that maybe some crude hack could ameliorate them.
> For those of you thinking that TSMC only gets set back by the time it took to recover the equipment from the virus (1-2 days), realize that there are some critical steps in the manufacturing process that require completion within X time or the wafer is trash. Also realize that wafers take several weeks of fab processing, and this may be a substantial hit to their output for a while.
Everything in semiconductor is basically incomprehensible in scale. A scanner (i.e., the photo lithography projection tool) takes about 2 seconds to fully expose a wafer. that wafer probably has 100 individual chips on it each of which have around 2 billion transistors. That means that tool is helping create 100 billion transistors a second.
The great grand parent comment is right...but the lose of that is probably on the range of one-two weeks production. retrofitting the fab like you suggest, and to be clear it isn't a fundamentally bad idea, would cost billions and take months if not years. What you propose is technically correct but business irrelevant.
Long term here means a week or so...it's expensive but rare. They don't play with 'crude hacks' because you don't know the implications of that hack 10 years from now when the chip is running part of the stock market.
It's just an industry that is hard to process, whether you work in it or not, because of the scale and the precision.
In school (industrial engineering) we talked about length and thickness tolerances being quite tight at 1/10,000 inch. The units used in semiconductors are nanometers, angstroms, etc. You might do a process and lay down just a couple atom thick layer of material...I had no idea that was physically possible.
Semiconductors still blow me mind...eventually we will run out of base silicon to use and are possibly really fucked but its been a fun ride so far.
No, thats not real, that's a silly science fiction novel.
What does that mean? Is 'yield' not the end usable product from the batch?
It's a familiar concept from organic chemistry.
Edit: If yield per step averages 99.8%, and there are 500 steps, overall yield is 36.8%.
At the same time, when wafers get scrapped, they do justify why they were scrapped. There are metrology processes and tests performed as you go to ensure you don't run ruined wafers through additional manufacturing steps.
The gist of that part is meant to show how important and impressive the entire process is. In "normal" manufacturing, 99.8% good parts is a pretty darn good process. Many of the easy wins are already implemented. Most normal things are manufactured in far fewer steps, so even if you're only making 95% good parts, it doesn't absolutely kill your total recovery (start to finish).
One former employer, a semi equipment company, had a weekly Monday Morning 'Crash Report'. Our tools performed a wet chemistry etch step on 25 wafers at at time. If the control system failed, the entire lot was in peril. So Monday AM, we'd hear from the CEO which fab managers had called him over the weekend, screaming about the value of the wafers our tools had destroyed. Usually in the $50,000 - $250,000 range. Fun times.
Same thing with your OS/2 system. As long as it's working, there's really no need to change it. The fun begins when it no longer works and needs to be replaced. How much of the factory will then need to be replaced/updated just because the controlling computer can no longer operate the older equipment? That's the type of scenarios that give managers nightmares.
The main defense is a computer at the entrance where technicians are supposed to scan their USB drives. It's a devils choice really...do you put the tools on an externally accessible network? If not how do engineers get data off of tools? how does the factory talk to itself and schedule things?
I don't envy FAB IT. Utterly thankless.
Open Source Software may or may not be easy or economically realistic to port, but at least the users have a say.
Upload instructions via punch cards
The machines at TSMC would be at 100% utilization on million dollar jobs, management would never accept downtime for maintenance for software updates that could introduce bugs.
Its one thing for consumer devices to receive updates, its a completely different ballgame with industrial. Downtime due to anything can be millions of dollars per hour in losses. So it comes down to what could cause more monetary loss, downtime due to hacks or downtime due to bugs introduced.
"If it works why break it".
Its the same reason why there are production lines where physically, hardware could be replaced and improved to reduce wear, reliability, power usage, etc (even things like motors) but they arent, for decades. Only when things start costing money outside the original design do engineers perform upgrades.
This is extra true for my company. We sell sorters, which don't actually do anything useful in terms of processing the wafers. The tools just shuffle the wafers between FOUPs. While these tools help customers optimize processes by changing batch sizes and such, they really want to have as few non-process tools as possible. So uptime is really important.
Can we stop repeating this as a strength of OSS? It definitely is not. "Users" have a problem they want solved, they don't really want that problem and to learn how to patch software.
Back when I made rocket things, we used an RTOS. Are real-time operating systems (like QNX) not widely used?
But QnX real-time capabilities are just one nice part of the mix, the user land drivers and impossible to crash kernel are equal partners in giving it the stability that it has. Process isolation for drivers should be mandatory.
I still think it's unlikely that someone would go through the effort to insert a super secret backdoor by surreptitiously modifying the masks but there are some interesting techniques that can make finding a backdoor almost impossible if you don't already know about it.
However, you must remember that as well as precise knowledge of the circuit, anyone other than an insider has close to zero chance of getting a doping change correct. Even an insider's chances are very low.
And then your high-level testing is in place too. It's not common to have circuits where BIST can't give you full confidence but it happens; for things like the RNG here, also due to test tool limitations etc. So you must be doing both both general and highly targeted post-manufacturing testing also. The extent of that testing may depend on your market.
Actual backdoor? almost impossible.
A backdoor would have to change the interconnections within the chips. That isn't a function performed by the FAB software. The design of the chip circuitry is designed much earlier. Once validated and released it is then laser / ion beam etched into a series of 'masks.' The mask represent the different layers of the chip that make up the interconnections. They are used in photolithography and are typically made elsewhere and then used thousands of times. Like a photo.
To put a backdoor in the chip you would have to, undetected, hack the design side of a chip company. And do it early enough that without being noticed the backdoor is created into the masks which then get built into all of the chips and still remain unnoticed.
It would be much easier to bribe a couple employees.
Edit: a simple analogy - lets say you hack my oven. You can burn my cake and undercook it and give me food poisoning. But you can't swap the salt for sugar in the pan unless you actually had physical access.
- Competing fabs
- Competitors to Apple
- China (nationalist sentiment or something to do with the recent IP theft court cases)
Water feature near Apple’s new cupertino headquarters set to rise tens of feet over the next century, displacing engineers in low lying areas.
Political instability set to double the prices of raw materials used in domestically produced Mac Pros; iPhones largely unaffected.
Suspected cancer link discovered with cafeteria subcontractor Monsanto’s Roundup. Rumors suggest Apple will move to in house agricultural production. Monsanto down 5 points.
"Hey, kid, don't bite that Apple®!"
What's a better, concise way to describe TSMC? I think "World's biggest contract fab" can probably be improved on.
Prompted me to look up the numbers though. Apple could buy TSMC for cash, four times over... pretty incredible.
Regarding the 2019 Taiwan Independence referendum, the Foundation’s data shows that 20.7% of the population are incredibly in favor of the vote and 28.8% generally approve, indicating that over half of the population support the referendum.
Most Taiwanese consider Taiwan, China separate countries, poll suggests
Nearly 70 percent of Taiwanese are willing to go to war if China were to attempt to annex Taiwan by force
Taiwanese people are Chinese people, as is much of Singapore and Hong Kong.
I’m not sure what your referendum links have to do with anything.
I would also suggest that saying the people of Taiwan consider themselves to be Chinese, ethnically and nationally, is true but not so helpful, given that the other China is similarly full of people who consider themselves to be Chinese, ethnically and nationally. What you said is true, but missing an awful lot of important distinction.
Lost production at TSMC is a serious issue, but it's not cataclysmic for the supply chain as a whole.
Did Samsung boot other customers or products so NVidia could stay afloat? I’m sure NVidia’s margins are high enough to get others to slow down their output.
This kind of issue happens in pharmaceuticals all the time: one factory goes down, the others can’t soak up the extra orders, and months down the line we start running out of finished product after the warehouse gets emptied.
I have long noticed that Apple "related" news make it to front pages that usually do not carry any tech news at all.
My understanding for why this happens is that media outlets are old school Apple strongholds. In large part because the current generation of media people have been educated by a generation that learned their trade by rote on gray scale Macs.
Mental inbreeding, basically...
Wonder who shorted AMD/Nvidia recently
2. intel aren't that stupuid