Design of a magnetic-pole enhanced inductively coupled plasma source

The trend towards large-area substrates stressed by the semiconductor and flat panel display (FPD) industries is propelling the large-area plasma source developments. In this work, a novel inductively coupled plasma source enabling large-area plasma production is presented: the magnetic-pole-enhanced inductively coupled plasma source (MaPE-ICP). The plasma source is based on the use of a coil inductor embedded within a high magnetic permeability pole to enhance the magnetic coupling between the coil and the plasma.

A 200 mm MaPE-ICP source has been fully characterized by Langmuir probe, magnetic induction probe and RF electrical parameter measurements. The plasma characteristics are compared to classical ICP source performances. RF electrical parameter measurements show that the current needed to sustain the plasma is halved with the use of a magnetic pole, thus lowering the coil resistive losses. The plasma uniformity is improved compared to that of a spiral coil source, with only a 5.5% variation within the area of the coil radius at 5 mTorr argon pressure. Preliminary plasma uniformity measurements carried out on a 800 mm×800 mm source show that a non-uniformity of 20% from the average values is achieved over 600 mm with more than 10¹¹ ion cm^-3. This demonstrates that the use of a magnetic pole to concentrate the magnetic flux is a key asset for scaling up ICPs.