Inductively coupled plasma source for plasma processing
View Patent ↗Plasma processing apparatus and methods are disclosed. Embodiments of the present disclosure include a processing chamber having an interior space operable to receive a process gas, a substrate holder in the interior of the processing chamber operable to hold a substrate, and at least one dielectric window. A metal shield is disposed adjacent the dielectric window. The metal shield can have a peripheral portion and a central portion. The processing apparatus includes a primary inductive element disposed external to the processing chamber adjacent the peripheral portion of the metal shield. The processing apparatus can further include a secondary inductive element disposed between the central portion of the metal shield and the dielectric window. The primary and secondary inductive elements can perform different functions, can have different structural configurations, and can be operated at different frequencies.
1. A method of processing a substrate in a plasma processing apparatus, the plasma processing apparatus comprising a processing chamber having an interior operable to receive a process gas, a substrate holder operable to hold a substrate, a first inductive element disposed over the process chamber interior, and a second inductive element disposed over the process chamber interior, the first and second inductive element each configured to inductively generate a plasma in the process chamber interior, the method comprising:
placing a substrate on the substrate holder within the interior of the processing chamber of the processing apparatus;
admitting a process gas into the interior of the processing chamber;
energizing the first inductive element with electromagnetic energy at a first RF frequency to generate inductively a plasma in the interior of the process chamber;
energizing the second inductive element with electromagnetic energy at a second RF frequency to generate inductively a plasma in the interior of the processing chamber;
selecting the first RF frequency to be sufficiently different from the second RF frequency to reduce interference between the first inductive element and the second inductive element through the inductively coupled plasma; and
processing the substrate in the plasma.
2. The method of claim 1 , wherein the first RF frequency is selected to be at least about 1.5 times greater than the second RF frequency.
3. The method of claim 1 , wherein the first RF frequency is selected to be about 13.56 MHz.
4. The method of claim 3 , wherein the second RF frequency is selected to be in the range of about 1.75 MHz to about 2.15 MHz.
5. The method of claim 1 , wherein a metal shield separates the first inductive element and the second inductive element in the plasma processing apparatus.