A method for doping a fin-based semiconductor device is disclosed. In one aspect, the method comprises patterning at least one fin, each fin comprising a top surface and a left sidewall surface and a right sidewall surface. The method further comprises providing a first target surface being the right sidewall of a first block of material. The method further comprises scanning a first primary ion beam impinging on the first target surface with an incident angle .alpha. different from zero degrees and thereby inducing a first secondary ion beam, and doping at least the left sidewall surface and possibly the top surface of the fin opposite to the first target surface with the first secondary ion beam.