Three-dimensional silicon-based capacitor, preparation method thereof and integrated passive device

The invention discloses a three-dimensional silicon-based capacitor which comprises a groove structure etched on a silicon substrate, conducting layers and dielectric layers are alternately deposited on the groove structure, different conducting layers are completely isolated through the dielectric layers, the groove structure comprises silicon column arrays and grooves between the silicon column arrays, the grooves are filled with isolation layers, and the isolation layers are arranged on the silicon column arrays. A first electrode layer is deposited on the top conductive layer and the isolation layer, so that the outermost conductive layer deposited on the groove structure is in ohmic contact with the first electrode layer; a redistribution layer is etched on the back face of the silicon substrate, and a second electrode layer is deposited on the back face of the silicon substrate, so that the innermost conductive layer deposited on the groove structure is in ohmic contact with the second electrode layer t