An integrated BiCMOS semiconductor circuit has active moat areas in silicon. The active moat areas include electrically active components of the semiconductor circuit, which comprise active window structures for base and/or emitter windows. The integrated BiCMOS semiconductor circuit has zones where silicon is left to form dummy moat areas which do not include electrically active components, and has isolation trenches to separate the active moat areas from each other and from the dummy moat areas. The dummy moat areas comprise dummy window structures having geometrical dimensions and shapes similar to those of the active window structures for the base and/or emitter windows.