Semiconductor device and method for manufacturing same

A semiconductor device comprising:

• a semiconductor switching element including:
• a drift layer having a first conductive type;
• a body region having a second conductive type and arranged on the drift layer;
• a first impurity region having the first conductive type, arranged in a surface portion of the body region in the body region and having an impurity concentration higher than the drift layer;
• a plurality of trench gate structures, each of which includes a trench having one direction as a longitudinal direction and reaching the drift layer from the first impurity region with penetrating the body region, and each of which has a double-layered structure in which a shield electrode, an intermediate insulation film, and a gate electrode layer are stacked in order through an insulation film in the trench;
• a high impurity concentration layer having the first conductivity type or the second conductive type, arranged on a side opposite to the body region to sandwich the drift layer between the high impurity concentration layer and the body region, and having an impurity concentration higher than the drift layer;
• an interlayer insulation film arranged on the trench gate structures, the body region and the first impurity region, and having a contact hole connecting the body region and the first impurity region;
• an upper electrode electrically connected to the first impurity region and the body region through the contact hole;
• and
• a lower electrode electrically connected to the high impurity concentration layer;
• wherein the shield electrode extends outward from an end portion of the gate electrode layer, and the intermediate insulation film is arranged between the shield electrode and a bottom surface of the gate electrode layer and between the shield electrode and the end portion of the gate electrode layer,
• wherein a distance of a portion between the end portion of the gate electrode layer and the shield electrode in the one direction and having an insulation property is defined as an effective insulation distance,
• wherein the effective insulation distance is larger than a thickness of a portion of the intermediate insulation film located at a bottom portion of the gate electrode layer,
• wherein the interlayer insulation film further has an embedded insulation film embedded between the intermediate insulation film and the end portion of the gate electrode layer,
• wherein the gate electrode layer includes a residual portion as a portion of the gate electrode layer detached from a main portion of the gate electrode layer,
• wherein the embedded insulation film, the intermediate insulation film, and the residual portion are arranged between the end portion included in the main portion of the gate electrode layer and the shield electrode, and
• wherein the effective insulation distance is a value equal to a sum of a thickness of a portion of the intermediate insulation film located at the end portion of the gate electrode layer and a width of the embedded insulation film.

A method for manufacturing a semiconductor device including a semiconductor switching element having a trench gate structure, the method comprising:

• preparing a substrate having
• a high impurity concentration layer with a first conductive type or a second conductive type, and
• a drift layer arranged on one surface side of the high impurity concentration layer, having the first conductive type and having an impurity concentration lower than the high impurity concentration layer;
• forming a plurality of trench gate structures by forming a plurality of trenches with one direction as a longitudinal direction in the drift layer, and stacking a shield electrode, an intermediate insulation film and a gate electrode layer in order through an insulation film in each of the trenches to form a double-layered structure;
• forming a body region having the second conductive type on the drift layer between the trenches;
• forming a first impurity region having the first conductive type with an impurity concentration higher than the drift layer in a surface portion of the body region in the body region;
• forming an interlayer insulation film on each of the trench gate structures, the body region, and the first impurity region;
• forming a contact hole connecting the body region and the first impurity region in the interlayer insulation film;
• forming an upper electrode electrically connected to the first impurity region and the body region through the contact hole;
• and
• forming a lower electrode electrically connected to the high impurity concentration layer,
• wherein the forming of the trench gate structures further includes:
• forming the shield electrode at a bottom surface of each of the trenches and an end portion of each of the trenches in the one direction through the insulation film;
• forming the intermediate insulation film on the shield electrode;
• forming the gate electrode layer on the intermediate insulation film, and then removing a portion of the gate electrode layer as a partial removal portion of the gate electrode layer at the end portion in the one direction;
• and
• embedding an embedded insulation film in the partial removal portion inside each of the trenches.