A heat sink (11) includes a base (12), a plurality of fins (14) extending from a first surface of the base, and a plurality of carbon nanotubes (18) formed on an opposite second surface (16) of the base. The carbon nanotubes are substantially parallel to each other and substantially perpendicular to the base. A method for manufacturing the heat sink includes the steps of: (a) providing a heat sink preform comprising a base and a plurality of fins extending from a first surface of the base; (b) polishing an opposite second surface of base; (c) depositing a catalyst film on the second surface of the base; and (d) providing a carbon source gas to grow a plurality of carbon nanotubes on the second surface of the base.