Methods for reducing etch nonuniformity in the presence of a weak magnetic field in an inductively coupled plasma reactor

A method of processing a substrate in a process chamber having a plurality of electromagnets disposed about the process chamber to form a magnetic field within the process chamber at least at a substrate level, the method comprising:

• determining a first direction of an external magnetic field present within the process chamber while providing no current to the plurality of electromagnets;
• sequentially providing a range of currents to the plurality of electromagnets to create a plurality of magnetic fields within the process chamber, each having a second direction opposite the first direction, wherein the second direction is substantially horizontal;
• determining a first magnetic field having a desired magnitude in the second direction of the plurality of magnetic fields over the range of currents;
• and
• processing a substrate in the process chamber using a plasma while statically providing the first magnetic field at the desired magnitude.

A method of processing a substrate in a process chamber having a plurality of electromagnets disposed about the process chamber to form a magnetic field within the process chamber at least at a substrate level, the method comprising:

• providing a plurality of currents over a range of values to the plurality of electromagnets to sequentially form a plurality of magnetic fields within the process chamber;
• measuring a magnitude of each of the plurality of magnetic fields;
• determining a first magnetic field having a desired magnitude from the plurality of magnetic fields;
• and
• processing a substrate in the process chamber using a plasma while statically providing the first magnetic field.