IGBT MANUFACTURING METHOD

摘要

PROBLEMS An IGBT which can suppress a variation of on-voltages even if a production variation of density of impurities is caused. MEANS OF SOLVING THE PROBLEMS A vertical IGBT includes a floating region of the first conductive type being formed within the body region of the second conductive type. A density of first conductive type impurities at a boundary of the floating region and the body region that is above the floating region is distributed to increase from an upper side to a lower side. A density of the first conductive type impurities at a boundary of the floating region and the body region that is under the floating region is distributed to decrease from an upper side to a lower side. A density of second conductive type impurities at a boundary of the floating region and the body region that is above the floating region is distributed to decrease from an upper side to a lower side. A density of the second conductive type impurities at a boundary of the floating region and the body region that is under the floating region is distributed to increase from an upper side to a lower side.