An arming switch structure and method of operation. The arming switch is integrated with a reactive material erasure device and phase change memory cell array and is coupled to a tamper detection device configured to trigger a signal for conduction to the reactive material erasure device that generates heat and induces a phase change in the phase change memory cell array. Prior to packaging, the memory chip is “armed” in a high-resistance state to prevent conduction of any signal to the reactive material erasure device. After the memory chip is packaged, the Reactive Material can be “disarmed” at a chosen time or condition by applying a bias to the arming switch activation layer, thereby heating and crystallizing the arming switch material, placing it in a low resistance state. In the disarmed state, the arming switch may conduct the trigger signal from tamper detection device to the reactive material erasure device.