A method of manufacturing a semiconductor device (1200), the method comprising forming a sacrificial pattern having a recess on a substrate (402), filling the recess and covering the substrate and the sacrificial pattern with a semiconductor structure, forming an annular trench in the semiconductor structure to expose a portion of the sacrificial pattern and to separate material (904) of the semiconductor structure enclosed by the annular trench from material (906) of the semiconductor structure surrounding the annular trench, removing the exposed sacrificial pattern to expose material of the semiconductor structure filling the recess, and converting the exposed material of the semiconductor structure filling the recess into electrically insulting material (1202).