Semiconductor device

A semiconductor device comprising:

• a semiconductor layer;
• a drift layer of a first conductivity type forming a surface layer portion of the semiconductor layer;
• an impurity region of a second conductivity type formed in a surface layer portion of the drift layer;
• a terminal region of the second conductivity type that is formed in the surface layer portion of the drift layer along a peripheral edge of the impurity region and that has a second conductivity type impurity concentration higher than a second conductivity type impurity concentration of the impurity region;
• a connection region formed in a region in which the peripheral edge of the impurity region and the terminal region are connected;
• a plurality of field limiting regions of the second conductivity type that are formed in the surface layer portion of the drift layer at intervals in a direction away from the terminal region, and that are formed such that distances between adjacent pairs of the field limiting regions become greater as distances from the terminal region become greater;
• an insulating layer that is formed on the semiconductor layer, and that has a first opening exposing the impurity region, the terminal region, and the connection region, and has a plurality of second openings each exposing the corresponding ones of the field limiting regions at intervals in the direction away from the terminal region;
• a surface electrode that has a connection portion connected to the impurity region, to the terminal region, and to the connection region inside the first opening of the insulating layer, and that has a drawn portion drawn out onto the insulating layer from the connection portion through the first opening and formed at an interval from the innermost field limiting region to the impurity region side as viewed in plan;
• a plurality of field electrodes that are formed on the insulating layer at intervals from the surface electrode and that are connected to the corresponding ones of the field limiting regions inside the corresponding second openings, respectively;
• and
• an organic insulating layer formed on the insulating layer so as to cover the drawn portion of the surface electrode and the plurality of field electrodes;
• wherein the insulating layer has a plurality of thin film portions covering peripheral portions of the corresponding ones of the field limiting regions, and a plurality of thick film portions covering regions between adjacent pairs of the field limiting regions such as to protrude upward relative to the thin film portions,
• the first opening of the insulating layer is defined by an inclined surface having an acute angle with respect to the semiconductor layer inside the insulating layer,
• the drawn portion of the surface electrode is drawn out onto the insulating layer through the inclined surface of the first opening from the connection portion, and faces the terminal region across the inclined surface of the first opening,
• the organic insulating layer is drawn out onto the connection portion of the surface electrode from on the drawn portion of the surface electrode, faces the impurity region, the terminal region and the connection region across the connection portion of the surface electrode, and partially exposes the connection portion of the surface electrode,
• the impurity region has the second conductivity type impurity concentration of 1.0×1016 cm-3 or more and 1.0×1017 cm 3 or less,
• the terminal region has the second conductivity type impurity concentration of 1.0×1017 cm-3 or more 5.0×1017 cm-3 or less, and
• a concentration ratio of the impurity region with respect to the terminal region is 0.225 or more and 1.0 or less.