The present invention relates to an ion implantation machine 100 that comprises: an enclosure 101 that is connected to a pump device 102; a plasma source 115-121-122; a bias power supply 113; a gas inlet 117 leading into the enclosure; and a substrate-carrier 104 connected to the negative pole of the bias power supply and arranged inside the enclosure. The machine is remarkable in that: the substrate-carrier 104 consists in at least two parallel plates 105-106; a reference electrode consists in at least one strip 110, this reference electrode being connected to the positive pole of the bias power supply; and the strip is interposed between the two plates.