A semiconductor structure with mixed n-type and p-type non-planar transistors includes a residual overlapping mask bump on one or more of the dummy gates. A dielectric layer is created over the structure having a top surface above the residual bump, for example, using a blanket deposition and chemical-mechanical underpolish (i.e., stopping before exposing the gate cap). The residual bump is then transformed into a same material as the dielectric, either in its entirety and then removing the combined dielectric, or by removing the dielectric first and partly removing the residual bump, the remainder of which is then transformed and the dielectric removed. In either case, the structure is planarized for further processing.