Nanometers refer to the gate width of a chip transistor.
A few nanometers does not refer to the size of the chip, but to the width of the gate inside the chip that makes up the smallest unit of silicon transistors. In the case of 5-nanometer chips, each chip is about 100 square millimeters in area, and the number of transistors inside is as high as 15 billion. The nano size of the chip is independent of the size of the chip, and the smaller the nano process, the more transistors.