SWITCHING ELEMENT

To reduce ON resistance of a switching element including an electric field relaxation region.SOLUTION: A switching element comprises: an n-type source region; a p-type body region; a plurality of p-type electric field relaxation regions each in contact with a gate insulator film on a bottom face of a corresponding trench; a p-type connection region connecting each electric field relaxation region to the body region; and an n-type drift region distributed from an inter-trench region through an interval region, which is positioned between the electric field relaxation regions, to a region at a lower side of each electric field relaxation region. The drift region in the interval region includes: a first high concentration n-type region in contact with a side face of a first electric field relaxation region; a second high concentration n-type region in contact with a side face of a second electric field relaxation region; and a low concentration n-type region which is disposed between the first high concentration n-type region and the second high concentration n-type region and has a lower n-type impurity concentration than the first high concentration n-type region and the second high concentration n-type region.SELECTED DRAWING: Figure 1 【課題】 電界緩和領域を有するスイッチング素子のオン抵抗を低減する。【解決手段】 スイッチング素子であって、ｎ型のソース領域と、ｐ型のボディ領域と、各々が対応する前記トレンチの底面でゲート絶縁膜に接するｐ型の複数の電界緩和領域と、前記各電界緩和領域を前記ボディ領域に接続するｐ型の接続領域と、前記トレンチ間領域から前記各電界緩和領域の間に位置する間隔領域を通って前記各電界緩和領域よりも下側の領域まで分布しているｎ型のドリフト領域、を有する。前記間隔領域内の前記ドリフト領域が、第１電界緩和領域の側面に接する第１高濃度ｎ型領域と、第２電界緩和領域の側面に接する第２高濃度ｎ型領域と、前記第１高濃度ｎ型領域と前記第２高濃度ｎ型領域の間に配置されているとともに前記第１高濃度ｎ型領域と前記第２高濃度ｎ型領域よりも低いｎ型不純物濃度を有する低濃度ｎ型領域、を有する。【選択図】図１