A method for fabricating a silicon submount for LED packaging. A silicon substrate is provided. A reflection layer is formed on the silicon substrate. Portions of the reflection layer and the silicon substrate are removed to form openings. A wafer backside grinding process is carried out to thin the silicon substrate thereby turning the openings into through silicon vias. An insulating layer is then deposited to cover the reflection layer and the silicon substrate. A seed layer is formed on the insulating layer. A resist pattern is then formed on the seed layer. A metal layer is formed on the seed layer not covered by the resist pattern. The resist pattern is then stripped. The seed layer not covered by the metal layer is then removed.