An electrical structure is provided that includes a dielectric layer present on a semiconductor substrate and a via opening present through the dielectric layer.An interconnect is present within the via opening. A metal semiconductor alloy contact is present in the semiconductor substrate. The metal semiconductor alloy contact has a perimeter defined by a convex curvature relative to a centerline of the via opening. The endpoints for the convex curvature that defines the metal semiconductor alloy contact are aligned to an interface between a sidewall of the via opening, a sidewall of the interconnect and an upper surface of the semiconductor substrate.