Integrated Circuit and Method of Forming an Integrated Circuit

A method of forming a contact structure, the method comprising:

• forming a trench that extends in a first direction from a main surface of a semiconductor body into the semiconductor body towards a rear surface of the semiconductor body, wherein forming the trench comprises:
• forming an upper trench portion;
• widening at least a part of the upper trench portion so as to form curved sidewalls in the upper trench portion that bow outward from a bottom of the upper trench portion;
• forming a lower trench portion having generally planar sidewalls extending from the bottom of the upper trench portion at a first depth into the semiconductor body along the first direction to a contact region at a second depth, the lower trench portion being narrower than the widened part of the upper trench portion;
• forming an insulation layer in the trench that completely lines the sidewalls and the bottom of the trench;
• removing a portion of the insulation layer from the bottom of the trench;
• and
• filling the trench with an electrically conductive material such that the electrically conductive material directly contacts the contact region.

A method of forming a semiconductor device, the method comprising:

• providing a semiconductor body comprising a main surface and a rear surface opposite the main surface;
• and
• forming a trench that extends from the main surface of the semiconductor body towards the rear surface, the trench comprising an upper trench portion and a lower trench portion,
• wherein the trench is formed such that:
• the upper trench portion comprises curved sidewalls that extend from the main surface to an intersection between the upper trench portion and the lower trench portion;
• and
• the lower trench portion comprises generally planar sidewalls that extend from the intersection to a bottom of the trench,
• wherein the upper trench portion comprises a first width corresponding to a distance between the curved sidewalls directly at the main surface;
• wherein the upper trench portion comprises a second width corresponding to a distance between the curved sidewalls at a first depth that is beneath the main surface,
• wherein the upper trench portion comprises a third width corresponding to a distance between the curved sidewalls at a second depth that is beneath the first depth,
• wherein the first, second and third widths are measured in a plane parallel to the main surface,
• wherein the second width is greater than the first width, and
• wherein the second width is greater than the third width.

A semiconductor device, comprising:

• a semiconductor body comprising a main surface and a rear surface opposite the main surface;
• and
• a trench that extends from the main surface of the semiconductor body towards the rear surface, the trench comprising an upper trench portion and a lower trench portion, the trench having a width measured along a plane parallel to the main surface;
• wherein:
• the upper trench portion comprises curved sidewalls that extend from the main surface to an intersection between the upper trench portion and the lower trench portion;
• the lower trench portion comprises generally planar sidewalls that extend from the intersection to a bottom of the trench;
• the width of the trench decreases moving from the maximum width location in the upper trench portion to the intersection;
• an insulation layer lining the curved sidewalls of the upper trench portion and the generally planar sidewalls of the lower trench portion, wherein the insulation layer has an opening at the bottom of the trench;
• and
• an electrically conductive contact electrode within the trench, wherein the contact electrode is electrically connected to the semiconductor body at the bottom of the trench and electrically insulated from the semiconductor body along the curved sidewalls and the generally planar sidewalls by the insulation layer.