Method of generating plasma having high ion density for substrate processing operation

Claim 1

A method of generating a high density of ions for a substrate processing operation, comprising: placing a substrate in a process chamber; introducing a process gas into the process chamber; generating a bias voltage on the substrate; providing an oscillating current to an induction coil defining in conjunction with the substrate a column of the process gas, the oscillating current in the induction coil establishing a strong axial time-varying magnetic field in the process gas column that accelerates electrons azimuthally inside of and proximate to the induction coil, the accelerated electrons creating a high electric field region in the process gas column inside of and proximate to the induction coil and mostly canceling the axial magnetic field inside of the high electric field region, thereby creating a low electric field region in the process gas column inside of the high electric field region; and maintaining the process gas in the process gas column at a pressure so that electron collisions in the high and low electric field regions ignite a plasma and cause an ion current to fall on the substrate, the induction coil being shaped so that portions of the substrate nearer to the induction coil receive a greater contribution of ion current from ionization in the high electric field region than portions of the substrate farther from the induction coil to equalize ion current falling across the substrate.

Claim 2

A method of generating a high density of ions for a substrate processing operation, comprising: placing a substrate in a process chamber; introducing a process gas into the process chamber; generating a bias voltage on the substrate; providing an oscillating current to an induction coil defining in conjunction with the substrate a column of the process gas, the oscillating current in the induction coil establishing a strong axial time-varying magnetic field in the process gas column that accelerates electrons azimuthally inside of and proximate to the induction coil, the accelerated electrons creating a high electric field region in the process gas column inside of and proximate to the induction coil and mostly canceling the axial magnetic field inside of the high electric field region, thereby creating a low electric field region in the process gas column inside of the high electric field region; and maintaining the process gas in the process gas column at a pressure so that electron collisions in the high and low electric field regions ignite a plasma and cause an ion current to fall on the substrate, the induction coil being shaped so that portions of the substrate nearer to the induction coil receive a greater contribution of ion current from ionization in the high electric field region than portions of the substrate farther from the induction coil to equalize ion current falling across the substrate.