Method of forming a semiconductor device having through silicon vias

A method of forming a semiconductor device, the method comprising:

• providing a semiconductor substrate having first and second surfaces opposed to each other;
• forming a plurality of transistors on the first surface of the semiconductor substrate;
• forming a first interlayer dielectric film to cover the plurality of transistors and the first surface of the semiconductor substrate;
• forming a first back insulating layer on the second surface of the semiconductor substrate, the first back insulating layer comprising a first insulating element;
• forming a second back insulating layer in direct contact with the first back insulating layer, the second back insulating layer comprising a second insulating element different from the first insulating element;
• forming an opening on the second back insulating layer and sequentially etching the first back insulating layer and the semiconductor substrate through the opening to form a substrate through hole;
• and
• forming a through silicon via in the substrate through hole, wherein the through silicon via has an exposed end face protruding out from the second back insulating layer, wherein forming the through silicon via comprises sequentially forming a seed layer and a through silicon via body.