An integrated circuit structure includes a semiconductor substrate including a first region and a second region; an insulation region in the second region of the semiconductor substrate; and an inter-layer dielectric (ILD) over the insulation region. A transistor is in the first region. The transistor includes a gate dielectric and a gate electrode over the gate dielectric. A first conductive line and a second conductive line are over the insulation region. The first conductive line and the second conductive line are substantially parallel to each other and extending in a first direction. A first metal line and a second metal line are in a bottom metal layer (M1) and extending in the first direction. The first metal line and the second metal line substantially vertically overlap the first conductive line and the second conductive line, respectively. The first metal line and the second metal line form two capacitor electrodes of a capacitor.