A one time programmable read only memory disposed on a substrate of a first conductive type is provided. A gate structure is disposed on the substrate. A first doped region and a second doped region are disposed in the substrate at respective sides of the gate structure, and the first doped region and the second doped region are of a second conductive type which is different from the first conductive type. A third doped region of the first conductive type is disposed in the substrate and is adjacent to the second doped region, and a junction is formed between the third doped region and the second doped region. A metal silicide layer is disposed on the substrate. An clearance is formed in the metal silicide layer, and the clearance at least exposes the junction.