Abstract: A method of manufacturing a semiconductor device comprises the steps of: forming a patterned masking layer (3) of insulating material at a surface (2) of a semiconductor body (1), etching the semiconductor body (1) through the patterned masking layer (3) so as to form a trench (8) in the semiconductor body (1), applying an insulating layer (10) which fills the trench (8) in the semiconductor body (1), the insulating layer (10) exhibiting a trough (11) above the trench (8), which trough (11) has a bottom area (12) lying substantially above the surface (2) of the semiconductor body (1), subjecting the semiconductor body (1) to a planarizing treatment so as to form a substantially planar surface (15), subjecting the semiconductor body (1) to a further treatment so as to expose the semiconductor body (1) and form a field isolating region (17), characterized in that the insulating layer (10) is removed substantially to the bottom area (12) of the trough (11) by means of chemical mechanical polishing using fi