Semiconductor device and manufacturing method thereof

The present invention provides a semiconductor device and a manufacturing method thereof. When a substrate contact plug is formed in a trench deeper than an element isolation trench in a circuit region and electrically connects a wiring and a semiconductor substrate, it is possible to effectively prevent the increase in the resistance value of the substrate contact plug due to the fact that the substrate contact opening ratio is small. A substrate contact plug (SP2) which is connected to a wiring (M1) and a semiconductor substrate (SB) and does not form a circuit is formed in a seal ring region (1B) in a peripheral portion of a semiconductor chip region. The substrate contact plug (SP2) is buried in a trench (D2) which is deeper than an element isolation trench (D1). 本发明提供种半导体装置及其制造方法。当在电路区域中形成在比元件分离用的槽深的槽内形成且将布线与半导体基板电连接的基板接触插塞的情况下，防止由于基板接触开口率不足引起的基板接触插塞的电阻值的增大。将连接到布线(M1)和半导体基板(SB)并且不构成电路的基板接触插塞(SP2)形成于半导体芯片区域的边缘部的密封环区域(1B)。将基板接触插塞(SP2)埋入于比元件分离用的槽(D1)深的槽(D2)内。