A metal-insulator-metal (MIM) capacitor structure includes a semiconductor substrate and a bottom conductive layer above the semiconductor substrate. The bottom conductive layer has a slanted sidewall with respect to a top surface of the semiconductor substrate. The MIM capacitor structure further includes a top conductive layer above the bottom conductive layer. The top conductive layer has a vertical sidewall with respect to the top surface of the semiconductor substrate. The MIM capacitor structure further includes an insulating layer interposed between the bottom conductive layer and the top conductive layer. The insulating layer covers the slanted sidewall of the bottom conductive layer.