Abstract: A memory structure including a substrate, charge storage layers, and a gate is provided. The charge storage layers are located on the substrate. The gate is located on the substrate on one side of the charge storage layers. The gate extends along a first direction. The gate has a protruding portion protruding along a second direction. The second direction intersects the first direction. The protruding portion is located between two adjacent charge storage layers arranged along the first direction.

Abstract: A physically unclonable function includes a flash memory, a current comparator and a controller. The flash memory includes a plurality of memory cells. A method of operating the physically unclonable function circuit includes the controller setting the plurality of memory cells to an initial data state, the controller setting the plurality of memory cells between the initial data state and an adjacent data state of the initial data state, the current comparator reading a first current from a memory cell in a first section of the plurality of the memory cells, the current comparator reading a second current from a memory cell in a second section of the plurality of the memory cells, and the current comparator outputting a random bit according to the first current and the second current.