alt Hacker News"and then it’ll take you a few years of producing substandard and defective memory chips before your yields start to look competitive."
As a complete know nothing about the fab industry, I am always puzzled by this. Do the fabs need to be seasoned like an iron cast skillet or something?
Replies
JrProgrammer • today at 11:46 AM
I can imagine that the process of fabrication relies on tweaking a tremendous amount of parameters. In a sense seasoning a skillet and perfecting it to the max
Kind of.
There's a mysterious fab entity known as "the Recipe" - the product of long iterative dialing in of the fab's operating parameters. Of which there are a great many. A modern fab performs hundreds of manufacturing steps, with thousands of tweakable parameters, and they may interact in non-obvious ways to affect the outcomes. This is what's discovered and adjusted as the fab runs.
The difference between having the Recipe and not having the Recipe is the difference between 96% yield and 12% yield.
Changing the process (i.e. 4nm to 2nm) is the most sure way to lose the Recipe. The fab knowledge you spent months and years of engineering work discovering will no longer apply. But you can also lose the Recipe by replacing fab hardware, by changing the suppliers, by an act of god, and more.