System and methods for VHF plasma processing
This disclosure relates to a plasma processing system for VHF plasma processing using a transmission antenna designed to enable a resonant VHF standing wave inside a plasma process chamber used to manufacture semiconductor devices. The system includes a transmission element capable of being electromagnetically coupled to incoming power lines connected to a power source. The transmission element, power transmission lines, and power source form a resonant circuit capable of enabling a VHF standing wave on the transmission element. The transmission element is folded back on itself to reduce the footprint of the antenna, such that the transmission element(s) can be located inside the plasma process chamber. The transmission antenna has three portions, with the first being electromagnetically coupled to the power transmission line, the second being coupled to plasma, and the third being a folded portion that reduces the transmission element's footprint.
1. A device, comprising:
a plasma processing chamber comprising an interior volume, a substrate holder disposed within the interior volume; and a power source disposed outside of the interior volume;
a power component coupled to the plasma processing chamber, the power component comprising one or more power transmission lines electrically connected to the power source;
a transmission element disposed between the power component and the substrate holder, the transmission element being electrically insulated from the one or more power transmission lines and arranged adjacent to at least one of the one or more power transmission lines to permit electromagnetic coupling between the at least one power transmission line and the transmission element, the transmission element comprising:
a dielectric structure comprising a surface that is opposite the substrate holder; and
one or more transmission antennas having an overall length configured to enable a standing wave at a frequency of 30 MHz to 300 MHz, the one or more transmission antennas being embedded within the dielectric structure such that the dielectric structure blocks current flow from the at least one power transmission line to the one or more transmission antennas but permits said electromagnetic coupling between the at least one power transmission line and the one or more transmission antennas, wherein each of the one or more transmission antennas comprises a conductive structure that is folded forming an open loop including plurality of vertical portions of each of the transmission antennas that extend along a vertical direction from the power component to the substrate holder.
2. The device of claim 1 , wherein the power component comprises two or more power transmission lines electrically connected to the power source.
3. The device of claim 2 , wherein the transmission antenna comprises two or more transmission antennas being arranged to be electromagnetically coupled with a corresponding power transmission line.
4. The device of claim 1 , wherein the dielectric structure comprises alumina, quartz, silicon carbide, or combination thereof.
5. The device of claim 1 , wherein the dielectric structure comprises an yttrium oxide coating on at least one surface.
6. The device of claim 1 , wherein the transmission antenna comprises two or more transmission antennas being arranged to be electromagnetically coupled with a corresponding power transmission line of the power component, and the dielectric structure comprises a coupling component embedded within the dielectric structure, the coupling component comprising a conductive element arranged to form a capacitor between the two transmission antennas.
7. The device of claim 1 , wherein the transmission antenna comprises a length based, at least in part, on forming a resonance circuit between the power transmission line and the transmission element when the power source applies energy to the power transmission line at a frequency of 30 MHz to 300 MHz.
8. The device of claim 7 , wherein the resonance circuit is based, at least in part, on impedance of the transmission antenna.
9. The device of claim 1 , wherein the transmission antenna comprises a length based, at least in part, on impedance matching between the transmission antenna, the power transmission line, and the power source.
10. The device of claim 1 , wherein the power source comprises an operating frequency range of 30 MHz to 300 MHz.
11. The device of claim 1 , wherein the plasma processing chamber comprises two or more transmission elements.
12. The device of claim 1 , wherein,
the conductive structure of each antenna further comprises a plurality of horizontal portions extending in a direction along a surface of the substrate holder, each horizontal portion being provided at a different distance from the substrate holder along the vertical direction, and
each vertical portion is connected to at least one of said horizontal portions by at least one fold.