Plasma Treatment System

An apparatus for treating first and second workpieces of differing thicknesses with plasma, each of the first and second workpieces having an exposed surface, the apparatus comprising:

• a vacuum chamber having a chamber base and a chamber lid movable relative to said chamber base between a closed position that defines a processing space and an open position for transferring the first and second workpieces into and out of said processing space;
• a vacuum port in said vacuum chamber for evacuating said processing space;
• a workpiece holder located in said processing space and configured to hold either the first workpiece or the second workpiece in an horizontal plane;
• a process gas supply port in said vacuum chamber for introducing a process gas to said processing space;
• a plasma excitation source positioned in said chamber lid, the plasma excitation source including a powered electrode in a plane parallel to the plane of either the first workpiece or the second workpiece and operable to provide a plasma in said processing space from the process gas, a grounded plate, and a plasma cavity formed between said powered electrode and said grounded plate the distance from said powered electrode to the exposed surface of the first workpiece having a first thickness defines a desired separation, said grounded plate including a plurality of openings positioned below said powered electrode in a plane parallel to the plane of said powered electrode, and said plurality of openings connecting said plasma cavity and said processing space, prohibiting the transfer of at least a portion of ions in the plasma from said plasma cavity to said processing space, and allowing the transfer of at least a portion of free radicals in the plasma from said plasma cavity to said processing space;
• and
• a sidewall section capable of being removed from or added to said chamber lid for changing a vertical dimension of said vacuum chamber and for maintaining the desired separation when the second workpiece having a second thickness different than the first thickness replaces the first workpiece.

A method of sequentially plasma treating first and second workpieces of differing thicknesses in a processing space of a vacuum chamber having a chamber lid and a powered electrode positioned in the chamber lid in a horizontal plane, the method comprising:

• placing the first workpiece having an exposed surface and a first thickness in the processing space and in a plane parallel to the plane of the powered electrode wherein the distance from the powered electrode to an exposed surface of the first workpiece defines a desired separation distance;
• creating a plasma in the processing space to treat the first workpiece;
• removing the first workpiece from the processing space;
• placing a second workpiece having an exposed surface and a thickness different than the first workpiece in the processing space;
• adding or removing at least one sidewall section to the chamber lid to maintain the distance between the powered electrode and an exposed surface of the second workpiece at the desired separation distance;
• creating a plasma in the processing space to treat the second workpiece;
• and
• removing the second workpiece from the processing space.