this post was submitted on 06 Dec 2024
167 points (97.7% liked)
Technology
60123 readers
2676 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each another!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
Approved Bots
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
I was curious how bad 10% was, so I went digging to see what it should be.
A "good" yield target on a modern process is something like 60-70%, so this is a shocking shockingly bad oof, though it's also not a complete process, so it's possible they can salvage this and turn it into something viable but, still, oof.
Talking about the "yield" of a process doesn't make any sense. Yield is a metric for a specific chip fabricated on a given process. This depends heavily on the size of the chip and mitigation techniques.
The "correct" metric to compare processes is defect density (in defects per square cm). Intel claims that their defect density is below 0.4 defects/cm²: https://www.tomshardware.com/tech-industry/intel-says-defect-density-at-18a-is-healthy-potential-clients-are-lining-up. This would be relatively high but not much worse than what TSMC has seen for their recent nodes: https://www.techpowerup.com/forums/threads/intel-18a-process-node-clocks-an-abysmal-10-yield-report.329513/page-2#post-5387835).
Does this mean that errors happen on a later stage of production? How do we get from defects/cm to yield?
Yield is the percentage of chips that are functional. Roughly, you can think of it as the probability of a chip having 0 defects. The bigger the chip, or the higher the defect density, the lower this probability becomes. Chip designers will also include mitigation techniques (e.g. redundancy) to allow chips to work even with some defects.
Because there are so many small parts to a processor you need 99.99+% at most stages to stand any chance of mass production. In this context 60-70% is seriously impressive. Millions of things have to be done right to get this type of yield.