A capacitor array structure which includes N capacitor units is provided. Each capacitor unit includes a first metal layer, a second metal layer, and a third metal layer to form an upper electrode and a lower electrode. The second metal layer is disposed between the first metal layer and the third metal layer, and includes a second patterned metal portion of the lower electrode and a first patterned metal portion of the upper electrode. disposed above. The second patterned metal portion of the lower electrode has an opening, and a side of the first patterned metal portion of the upper electrode is exposed in the opening, such that the side of the first patterned metal portion of the upper electrode is adjacent to the lower electrode of another capacitor unit.