The present invention concerns a method comprising the steps of: introducing a substrate comprising a surface to be coated in a low-pressure reaction chamber; exposing said surface to a plasma during a treatment period within said reaction chamber; ensuring a stable plasma ignition by applying a power input, characterized in that the power input is continuously strictly higher than zero Watt (W) during said treatment period and comprises at least a lower limit power and at least an upper limit power strictly larger than said lower limit power, thereby obtaining a substrate with a coated surface. The present invention further concerns an apparatus for treating a substrate with a low-pressure plasma process and a substrate treated as such.