Physically unclonable function device and cryptographic key generation apparatus using the same

A cryptographic key generation apparatus, comprising:

• an array in which a plurality of physically unclonable function devices are arranged,
• wherein one of the plural physically unclonable function devices comprises a spin-torque generating layer;
• a magnetic free layer;
• a tunnel barrier layer;
• a spacer layer;
• and an indirect exchange interaction layer,
• wherein the spin-torque generating layer generates a Spin-Orbit Torque (SOT) when a current flows in an in-plane direction,
• the magnetic free layer has Perpendicular Magnetic Anisotropy (PMA), and
• the indirect exchange interaction layer comprises a first magnetic layer, a non-magnetic intermediate layer, and a second magnetic layer, wherein a magnetization direction between the first magnetic layer and the second magnetic layer is determined to be a parallel or antiparallel state according to a thickness of the non-magnetic intermediate layer, and when the magnetization direction of the indirect exchange interaction layer is the antiparallel state, stray magnetic fields of the first and second magnetic layers cancel each other out so that switching of the magnetic free layer does not occur, and when the magnetization direction of the indirect exchange interaction layer is the parallel state, the stray magnetic fields reinforce each other so that switching of the magnetic free layer occurs, and a cryptographic key is generated according to random output values based on different indirect exchange interaction characteristics due to process variability based on a change in a thickness of the non-magnetic intermediate layer in the array.