When making gate recesses in a FET, we use a mixture of which etches through about 10,000x faster than which means we can put a thin 5nm layer of to essentially stop our etch at a precise depth.
When making gate recesses in a FET, we use a mixture of which etches through about 10,000x faster than which means we can put a thin 5nm layer of to essentially stop our etch at a precise depth.