Patent ID: 7875894

Claim:
A semiconductor device comprising: a semiconductor chip having two main surfaces; a plurality of electrode pads on one of the two main surfaces of the semiconductor chip, each of said electrode pads having a top face; an insulation film on said one main surface of the semiconductor chip such that the top face of each of said electrode pads is exposed; a rewiring pattern having a plurality of interconnects connected to said electrode pads respectively, and which extend over said insulation film; a plurality of column-shaped electrodes connected to said plurality of interconnects, respectively and standing in a direction perpendicular to said one main surface, each of said column-shaped electrodes having a main body section connected to one of the interconnects and a protrusion section extending from said main body section, each said protrusion section having a top face, said main body section having a substantially flat top face, said protrusion section extending perpendicularly upwards from the flat top face of said main body section, and said protrusion section having a cross-sectional diameter in a direction parallel to said one main surface that is smaller than a cross-sectional diameter of said main body section in the direction parallel to said one main surface; a sealing section on said rewiring pattern and said insulation film, said sealing section buries said column-shaped electrodes and has a top face having a same height as the top faces of said protrusion sections of said column-shaped electrodes; a plurality of trench sections in said sealing section, each of said trench sections having a depth from the top face of said sealing section to a boundary between said protrusion section and said main body section such that side faces of each said protrusion sections are exposed by said trench sections; and a plurality of solder balls, said solder balls being respectively over said protrusion sections such that said solder balls are respectively electrically connected with said column-shaped electrodes by being bonded to the top face and said side faces of said protrusion sections, wherein a cross-sectional shape of said protrusion section and a cross-sectional shape of said main body section in the direction parallel to said one main surface are respectively square and circular.