US Patent 9811689 Chip ID generation using physical unclonable function

A method for generating a data set on an integrated circuit including programmable resistance memory cells includes applying a forming pulse to all members of a set of the programmable resistance memory cells. The forming pulse has a forming pulse level characterized by inducing a change in resistance in a first subset of the set from an initial resistance range to an intermediate resistance range, while after the forming pulse a second subset of the set has a resistance outside the intermediate range. The method includes applying a programming pulse to the first and second subsets. The programming pulse has a programming pulse level characterized by inducing a change in resistance of the first subset from the intermediate range to a first final range, while after the programming pulse the second subset has a resistance in a second final range, whereby the first and second subsets store said data set.