Patent ID: 11961883
Assignee: ROHM CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. An IGBT (Insulated Gate Bipolar Transistor) semiconductor device comprising:
a semiconductor layer of a first conductivity type having a first main surface on one side and a second main surface on the other side, the semiconductor layer includes a device region and an outside region outside the device region at the first main surface;
an impurity region of a second conductivity type formed in a surface layer portion of the first main surface in the device region;
a first field limiting region of the second conductivity type formed in the surface layer portion of the first main surface in the outside region while being spaced from the impurity region;
a second field limiting region of the second conductivity type formed in the surface layer portion of the first main surface in the outside region arranged outside of the first field limiting region;
a third field limiting region of the second conductivity type formed in the surface layer portion of the first main surface in the outside region arranged outside of the second field limiting region;
a fourth field limiting region of the second conductivity type formed in the surface layer portion of the first main surface in the outside region arranged outside of the third field limiting region;
a well region of a second conductivity type formed in a region between the impurity region and the first to fourth field limiting regions in the surface layer portion of the first main surface in the outside region, the well region having a bottom portion positioned at the second main surface side with respect to a bottom portion of the impurity region;
an emitter electrode formed over the device region and a part of the outside region; and
an insulating layer formed above the first to fourth field limiting regions, wherein
a field electrode arranged on the insulating layer such as to face the fourth field limiting region across the insulating layer and formed in an electrically floating state,
a distance between the first field limiting region and the second field limiting region is smaller than a distance between the second field limiting region and the third field limiting region, and a distance between the second field limiting region and the third field limiting region is smaller than a distance between the third field limiting region and the fourth field limiting region,
the field electrode includes a curved side wall that is obliquely inclined and include a portion the curved side wall becomes steeper as it becomes closer to a center of the field electrode in a cross section, and
the emitter electrode is electrically connected with the well region, and surface of the emitter electrode is formed with a step portion and the step portion is formed above the well region.