Look at FinFET transistors; this is the style of MOSFET currently employed at the smallest scales that I know of; This is what started calling the feature siz

Look at FinFET transistors; this is the style of MOSFET currently employed at the smallest scales that I know of; This is what started calling the feature size of the process node smaller and smaller past 24nm- at least for recent processes, the smallest parts of the "fin" were getting down in the 10-7nm range, and smaller.... but this isn't the size of the whole transistor, it needs multiple fins on either side to make the gate structure. So this was what happened when we end from talking about MOSFET feature size to the single-digit process node sizes that are essentially marketing terms now verses actual gate size. There are actual density increases do to the packing of these type of FinFETs vs. more traditional MOSFETS. Thus the efficiency gains that have been happening. Among other reasons. Or at least that is my understanding.