A method for manufacturing an interconnect structure and an interconnect structure are provided. The method includes: forming an opening in a substrate; forming a low-k dielectric block in the opening; forming at least one via in the low-k dielectric block; and forming a conductor in the via. The interconnect structure includes a substrate, a dielectric block, and a conductor. The substrate has an opening therein. The dielectric block is present in the opening of the substrate. The dielectric block has at least one via therein. The dielectric block has a dielectric constant smaller than that of the substrate. The conductor is present in the via of the dielectric block.