An ICP source with a shape-adjustable coil for ULSI

Summary form only given. A novel coil design for inductively-coupled plasma (ICP) sources for ULSI processing will be presented. To widen the operation range of processing systems based on ICP high density plasma sources, the coil shape is made adjustable by varying the height of the center post connected to a planar coil. The coil is then essentially shallow-dome-shaped with its height adjustable. As the coil shape changes, the profile of the RF field also changes, which in turn changes the location where the major RF power is deposited. Ideally, one can make use of this extra knob to compensate the changes in plasma uniformity as the system parameters such as gas pressure, RF power or bias power are varied. The other feature of the new coil design is that the coil has two sets of multi-turns winding connected in parallel but 180 degree opposite azimuthally. This arrangement can improve the symmetry of the processing system in azimuth direction which has been shown to be highly dependent on the symmetry of the coil. Initial measurements for a proof-of-principle experiment show that the density profile does change with the coil shape as the gas pressure and RF power are fixed.