A capacitor and a method of fabricating the capacitor are provided. The capacitor includes a structure for forming a three-dimensional capacitor, the structure being a pillar structure or a trench structure; where when the structure is a pillar structure, the aspect ratio of the pillar structure is more than 10; when the structure is a trench structure, the capacitor further includes a substrate, the trench structure is formed by a material layer disposed on the surface of a base trench of the substrate, and the aspect ratio of the trench structure is more than 10. The aspect ratio of the pillar structure of the capacitor or the aspect ratio of the trench structure may be more than 10, so that the performance of the capacitor is better.