Apparatus and method for tuning electrode impedance for high frequency radio frequency and terminating low frequency radio frequency to ground
Embodiments of the present invention relate to apparatus for improving uniformity and film stress of films deposited during plasma process of a substrate. According to embodiments, the apparatus includes a tuning electrode and/or a tuning ring electrically coupled to a variable capacitor for tuning high frequency RF impedance of the electrode and a low frequency RF termination to ground. The plasma profile and resulting film thickness can be controlled by adjusting the capacitance of the variable capacitor and the resulting impedance of the tuning electrode. The film stress of the film deposited on the substrate can be controlled, i.e., increased, by terminating the low frequency RF during processing.
1. A plasma processing apparatus, comprising:
a chamber body and a powered gas distribution manifold enclosing a process volume;
a pedestal disposed in the process volume for supporting a substrate;
a tuning electrode disposed within the pedestal and connected directly to a first terminal of a tuning electrode capacitor further having a second terminal, the second terminal of the tuning electrode capacitor connected directly to a first terminal of a first tuning electrode inductor further having a second terminal attachable directly to ground, wherein the first terminal of the tuning electrode capacitor is connected directly to a first terminal of a second tuning electrode inductor further having a second terminal attachable directly to ground, wherein the tuning electrode capacitor is directly connected in series with the first tuning electrode inductor and wherein the tuning electrode capacitor and the first tuning electrode inductor are directly connected in parallel with the second tuning electrode inductor; and
a conductive tuning ring disposed between the chamber body and the powered gas distribution manifold.
2. The plasma processing apparatus of claim 1 , wherein the tuning electrode capacitor is a variable capacitor.
3. The plasma processing apparatus of claim 2 , wherein the tuning electrode capacitor is coupled to a sensor and a controller configured to control the capacitance of the tuning electrode capacitor.
4. The plasma processing apparatus of claim 1 , wherein the tuning electrode capacitor is a first tuning electrode capacitor and the apparatus further comprises a second tuning electrode capacitor in series with the first tuning electrode inductor.
5. The plasma processing apparatus of claim 4 , wherein the tuning electrode is electrically coupled to a DC power source.
6. The plasma processing apparatus of claim 1 , wherein the conductive tuning ring is electrically coupled to a tuning ring capacitor and a tuning ring inductor to ground, wherein the tuning ring capacitor and the tuning ring inductor are configured in parallel.
7. The plasma processing apparatus of claim 6 , wherein the tuning ring capacitor is a variable capacitor.
8. The plasma processing apparatus of claim 7 , wherein the tuning ring capacitor is coupled to a sensor and a controller configured to control the capacitance of the tuning ring capacitor.
9. A substrate support assembly for use in a plasma processing apparatus, comprising:
a substrate support pedestal;
a tuning electrode disposed within the substrate support pedestal;
a tuning electrode capacitor having a first terminal and a second terminal, the first terminal of the tuning electrode capacitor connected directly to the tuning electrode;
a first tuning electrode inductor having a first terminal and a second terminal, the second terminal of the tuning electrode capacitor connected directly to the first terminal of the first tuning electrode inductor, the first tuning electrode inductor directly connected in series with the tuning electrode capacitor, wherein the second terminal of the first tuning electrode inductor is directly to ground; and
a second tuning electrode inductor having a first terminal and a second terminal, the first terminal of the second tuning electrode inductor connected directly to the first terminal of the tuning electrode capacitor and the second terminal of the second tuning inductor connected directly to the second terminal of the first tuning electrode inductor, the second tuning electrode inductor connected directly in parallel with the tuning electrode capacitor and the first tuning electrode inductor.
10. The substrate support assembly of claim 9 , wherein the tuning electrode capacitor is a variable capacitor.
11. The substrate support assembly of claim 10 , further comprising a sensor coupled to the tuning electrode.
12. The substrate support assembly of claim 9 , wherein the tuning electrode capacitor is a first tuning electrode capacitor, the assembly further comprising a second tuning electrode capacitor in series with the tuning electrode inductor.
13. The substrate support assembly of claim 9 , wherein the tuning electrode comprises a conductive mesh.
14. The plasma processing apparatus of claim 1 , wherein the tuning electrode capacitor is solely in series with a second tuning electrode inductor.
15. The substrate support assembly of claim 9 , wherein the second tuning electrode inductor is in sole series with the tuning electrode capacitor.