Semiconductor device and manufacturing method therefor

A method for manufacturing a semiconductor device, comprising:

• forming a metal layer on the entirety of a surface of a board having a through electrode that penetrates through the board in the thickness direction;
• etching the metal layer into shapes of a first metal pattern and a second metal pattern that are separated from each other at a predetermined space on the through electrode and that are in contact with the through electrode, while forming a groove at an upper part of the through electrode under the space between the first metal pattern and the second metal pattern;
• and
• supplying electric current from a back surface side of the board to both of the first metal pattern and the second metal pattern via the through electrode at the same time, thereby forming a plating layer that covers upper surfaces of the first metal pattern and the second metal pattern and an inner wall of the groove, by electroplating.