An apparatus which has the capability of filtering unwanted species from an extracted ion beam without the use of a mass analyzer magnet is disclosed. The apparatus includes an ion source having chamber walls that are biased by an RF voltage. The use of RF extraction causes ions to exit the ion source at different energies, where the energy of each ion species is related to its mass. The extracted ion beam can then be filtered using only electrostatic energy filters to eliminate the unwanted species. The electrostatic energy filter may act as a high pass filter, allowing ions having an energy above a certain threshold to reach the workpiece. Alternatively, the electrostatic energy filter may act as a low pass filter, allowing ions having an energy below a certain threshold to reach the workpiece. In another embodiment, the electrostatic energy filter operates as a bandpass filter.