Semiconductor device having an edge termination structure and manufacturing method thereof

A semiconductor device comprising:

• a semiconductor substrate having a drift region of a first conductivity type;
• an active portion, in which at least one of a transistor portion and a diode portion is provided in the semiconductor substrate;
• and
• an edge termination structure portion provided farther outward than the active portion in the semiconductor substrate,
• wherein the edge termination structure portion has:
• a plurality of guard rings of a second conductivity type provided in contact with an upper surface of the semiconductor substrate, and
• an embedded dielectric film arranged between two guard rings and at least partially embedded in the semiconductor substrate, and
• wherein the plurality of guard rings is provided below the embedded dielectric film,
• wherein the semiconductor device comprises a field plate provided from a position above the two guard rings to a position above the embedded dielectric film and formed of polysilicon,
• wherein the field plate has:
• a valley portion recessed toward the upper surface of the semiconductor substrate at a position where the field plate overlaps the embedded dielectric film;
• and
• an extension portion extending toward a position closer to a center of the embedded dielectric film than the valley portion.

A semiconductor device comprising:

• a semiconductor substrate having a drift region of a first conductivity type;
• an active portion, in which at least one of a transistor portion and a diode portion is provided in the semiconductor substrate;
• and
• an edge termination structure portion provided farther outward than the active portion in the semiconductor substrate,
• wherein the edge termination structure portion has:
• a plurality of guard rings of a second conductivity type provided in contact with an upper surface of the semiconductor substrate, and
• an embedded dielectric film arranged between two guard rings and at least partially embedded in the semiconductor substrate, and
• wherein the plurality of guard rings is provided below the embedded dielectric film,
• wherein the semiconductor device comprises a high concentration region of the first conductivity type provided in contact with the embedded dielectric film below the embedded dielectric film and having a higher doping concentration than that of the drift region, and
• wherein a net doping concentration NF_s (/cm3) at a boundary between the high concentration region and the embedded dielectric film satisfies a following formula, NF_s≥γ(1.35-0.6α)(1/(1−α))Nnet, wherein γ is a real number of 2 or greater, α is a ratio Na/Nd of a bulk acceptor concentration Na (/cm3) and a bulk donor concentration Nd (/cm3), and Nnet is a bulk net doping concentration (/cm3).