A few days ago, we published a report about Intel's 18A yields being at
an abysmal 10%. This sparked quite a lot of discussion among the tech community, as well as responses from industry analysts and
Intel's now ex-CEO Pat Gelsinger. Today, we are diving into known information about Intel's 18A node and checking out what the yields of possible products could be, using tools such as
Die Yield Calculator from SemiAnalysis. First, we know that the defect rate of the 18A node is 0.4 defects per cm². This information is from August, and up-to-date defect rates could be much lower, especially since semiconductor nodes tend to evolve even when they are production-ready. To measure yields, manufacturers use various yield models based on the information they have, like the aforementioned 0.4 defect density. Expressed in defects per square centimeter (def/cm²), it measures manufacturing process quality by quantifying the average number of defects present in each unit area of a semiconductor wafer.
Measuring yields is a complex task. Manufacturers design some smaller chips for mobile and some bigger chips for HPC tasks. Thus, these two would have different yields, as bigger chips require more silicon area and are more prone to defects. Smaller mobile chips occupy less silicon area, and defects occurring on the wafer often yield more usable chips than wasted silicon. Stating that a node only yields x% of usable chips is only one side of the story, as the size of the test production chip is not known. For example, NVIDIA's H100 die is measuring at 814 mm²—a size that is pushing modern manufacturing to its limits. The size of a modern photomask, the actual pattern mask used in printing the design of a chip to silicon wafer, is only 858 mm² (26x33 mm). Thus, that is the limit before exceeding the mask and needing a redesign. At that size, nodes are yielding much less usable chips than something like a 100 mm² mobile chip, where defects don't wreak havoc on the yield curve.