My understanding is that 200mm / 8-inch wafers on the older nodes is a literally dying technology. It's inefficient, it's costlier, it's just worse in all possible attributes.
180mm, and other similar nodes from the late 90s, are 200mm wafers. And since area is radius-squared, the modern 300mm wafer contains more than double the mm^2 and therefore double the chip-area.
Except 28nm process also shrinks the transistors by many magnitudes.
It's infeasible for 180mm to remain cost efficient against 40nm, 28nm, or 22nm.
Top-of-the-line 5nm or 3nm are far more expensive. But a 10+ year old 40nm fab has most of it's one-time-costs already paid for and overall has a more cost effective process in general due to the upgrade to 300mm wafers.
Thanks for the reply. I was not necessarily arguing for the ancient processes, but for the existence of tradeoffs between the process generations that don't instantly make the older processes obsolete. However, depending on how important having domestic chips is rated, seemingly obsolete processes might still have the advantage of lower setup cost.
180mm, and other similar nodes from the late 90s, are 200mm wafers. And since area is radius-squared, the modern 300mm wafer contains more than double the mm^2 and therefore double the chip-area.
Except 28nm process also shrinks the transistors by many magnitudes.
It's infeasible for 180mm to remain cost efficient against 40nm, 28nm, or 22nm.
Top-of-the-line 5nm or 3nm are far more expensive. But a 10+ year old 40nm fab has most of it's one-time-costs already paid for and overall has a more cost effective process in general due to the upgrade to 300mm wafers.