A structure includes a word line, a bit line, and an anti-fuse cell. The anti-fuse cell includes a reading device, a programming device, and a dummy device. The reading device includes a first gate coupled to the first word line, a first source/drain region coupled to the bit line, and a second source/drain region. The first source/drain region and the second source/drain region are on opposite sides of the first gate. The programming device includes a second gate, a third source/drain region coupled to the second source/drain region, and a fourth source/drain region. The third source/drain region and the fourth source/drain region are on opposite sides of the second gate. The dummy device includes a third gate, a fifth source/drain region coupled to the fourth source/drain region, and a sixth source/drain region. The fifth source/drain region and the sixth source/drain region are on opposite sides of the third gate.