Semiconductor device with improved breakdown voltage and high current capacity

A semiconductor device comprising:

• a semiconductor chip having a first major surface and a second major surface facing opposite to each other;
• an active section on the side of the first major surface for flowing current actively or passively;
• a low resistance layer of a first conductivity type on the side of the second major surface, the low resistance layer exhibiting low electrical resistance;
• a vertical drift section between the active section and the low resistance layer, the vertical drift section providing a substantially vertical drift current path in the ON-state of the semiconductor device, the vertical drift section being substantially depleted in the OFF-state of the semiconductor device;
• and
• a peripheral section formed between the first major surface and the low resistance layer, and formed around the vertical drift section, the peripheral section providing substantially no current path in the ON-state of the semiconductor device and being substantially depleted in the OFF-state of the semiconductor device,
• wherein the vertical drift section comprises a first alternating conductivity type layer comprised of first regions of the first conductivity type and first regions of a second conductivity type arranged alternately at a first pitch repeating along the first major surface,
• wherein the peripheral section comprises a first subsection and a second subsection, the second subsection being in the surface portion of the peripheral section between the first major surface and the first subsection,
• wherein the first subsection comprises a second alternating conductivity type layer comprised of second regions of the first conductivity type and second regions of the second conductivity type arranged alternately at the first pitch also repeating along the first major surface,
• wherein the second subsection comprises a third alternating conductivity type layer composed of third regions of the first conductivity type and third regions of the second conductivity type arranged alternately at a second pitch also repeating along the first major surface,
• wherein the second pitch is narrower than the first pitch, and
• wherein the width of the third regions of the second conductivity type is wider than the width of the third regions of the first conductivity type.

A semiconductor device comprising:

• a semiconductor chip having a first major surface and a second major surface facing opposite to each other;
• an active section on the side of the first major surface for flowing current actively or passively;
• a low resistance layer of a first conductivity type on the side of the second major surface, the low resistance layer exhibiting low electrical resistance;
• a vertical drift section between the active section and the low resistance layer, the vertical drift section providing a substantially vertical drift current path in the ON-state of the semiconductor device, the vertical drift section being substantially depleted in the OFF-state of the semiconductor device;
• and
• a peripheral section formed between the first major surface and the low resistance layer, and formed around the vertical drift section, the peripheral section providing substantially no current path in the ON-state of the semiconductor device and being substantially depleted in the OFF-state of the semiconductor device,
• wherein the vertical drift section comprises a first alternating conductivity type layer comprised of first regions of the first conductivity type and first regions of a second conductivity type arranged alternately at a first pitch repeating along the first major surface,
• wherein the peripheral section comprises a first subsection and a second subsection, the second subsection being in the surface portion of the peripheral section between the first major surface and the first subsection,
• wherein the first subsection comprises a second alternating conductivity type layer comprised of second regions of the first conductivity type and second regions of the second conductivity type arranged alternately at the first pitch also repeating along the first major surface, and
• wherein the second subsection comprises a region of the second conductivity type having a width wider than the first pitch.

A semiconductor device comprising:

• a semiconductor chip having a first major surface and a second major surface facing opposite to each other;
• an active section on the side of the first major surface for flowing current actively or passively;
• a low resistance layer of a first conductivity type on the side of the second major surface, the low resistance layer exhibiting low electrical resistance;
• a vertical drift section between the active section and the low resistance layer, the vertical drift section providing a substantially vertical drift current path in the ON-state of the semiconductor device, the vertical drift section being substantially depleted in the OFF-state of the semiconductor device;
• and
• base regions of a second conductivity type on the side of the first major surface,
• wherein the vertical drift section comprises a first alternating conductivity type layer composed of first regions of the first conductivity type and first regions of the second conductivity type arranged alternately at a first pitch repeating along the first major surface,
• wherein an outermost one of the base regions includes a first portion doped relatively lightly and a second portion doped relatively heavily,
• wherein the first portion is covered partly with an insulator film in the outer area of the second portion, and
• wherein the width of the first portion partly covered with the insulator film is wider than the first pitch.