Lateral plasma/radical source

A plasma source assembly comprising:

• a wedge-shaped housing having a gas inlet and a front face defining a flow path, the gas inlet allowing a flow of gas to move along the flow path to pass through the housing and out the front face;
• an RF hot electrode within the housing, the RF hot electrode having a first surface oriented substantially parallel to the flow path and a serpentine shape;
• and
• a return electrode within the housing, the return electrode having a first surface oriented substantially parallel to the flow path and spaced from the first surface of the RF hot electrode to form a gap, the return electrode having a complementary shape to the RF hot electrode to maintain substantially the same gap along a length of the serpentine shape.