There is provided semiconductor devices and methods of forming the same, the semiconductor devices including: a first semiconductor element having a first electrode; a second semiconductor element having a second electrode; a Sn-based micro-solder bump formed on the second electrode; and a concave bump pad including the first electrode opposite to the micro-solder bump, where the first electrode is connected to the second electrode via the micro-solder bump and the concave bump pad.

There is provided semiconductor devices and methods of forming the same, the semiconductor devices including: a first semiconductor element having a first electrode; a second semiconductor element having a second electrode; a Sn-based micro-solder bump formed on the second electrode; and a concave bump pad including the first electrode opposite to the micro-solder bump, where the first electrode is connected to the second electrode via the micro-solder bump and the concave bump pad.

A preform structure for soldering a semiconductor chip arrangement includes a carbon fiber composite sheet and a solder layer formed over the carbon fiber composite sheet.