Control of wafer bow in multiple stations
A system for controlling of wafer bow in plasma processing stations is described. The system includes a circuit that provides a low frequency RF signal and another circuit that provides a high frequency RF signal. The system includes an output circuit and the stations. The output circuit combines the low frequency RF signal and the high frequency RF signal to generate a plurality of combined RF signals for the stations. Amount of low frequency power delivered to one of the stations depends on wafer bow, such as non-flatness of a wafer. A bowed wafer decreases low frequency power delivered to the station in a multi-station chamber with a common RF source. A shunt inductor is coupled in parallel to each of the stations to increase an amount of current to the station with a bowed wafer. Hence, station power becomes less sensitive to wafer bow to minimize wafer bowing.
1. A power distributor comprising:
a plurality of low frequency paths configured to receive a low frequency modified radio frequency (RF) signal to output a plurality of low frequency RF signals;
a plurality of high frequency paths configured to receive a high frequency modified RF signal to output a plurality of high frequency RF signals, wherein each of the plurality of high frequency paths is coupled to a corresponding one of the plurality of low frequency paths;
a plurality of output paths configured to combine the plurality of low frequency RF signals and the plurality of high frequency RF signals to output a plurality of combined signals to a plurality of plasma processing stations, wherein each of the plurality of output paths is coupled to the corresponding one of the plurality of low frequency paths and a corresponding one of the plurality of high frequency paths; and
a plurality of shunt inductors configured to control a plurality of amounts of current provided to the plurality of plasma processing stations, wherein each of the plurality of shunt inductors is coupled to the corresponding one of the plurality of low frequency paths.
2. The power distributor of claim 1 , wherein each of the plurality of low frequency paths includes a first inductor and a second inductor of a high frequency blocking circuit, wherein the first inductor is coupled at a point to the second inductor, wherein each of the plurality of shunt inductors is coupled to the point of the corresponding one of the plurality of low frequency paths and to a ground connection.
3. The power distributor of claim 2 , wherein the point is coupled to a capacitor, wherein each of the plurality of shunt inductors is coupled in parallel to the capacitor of the corresponding one of the plurality of low frequency paths.
4. The power distributor of claim 1 , wherein each of the plurality of low frequency paths includes a capacitor, a first inductor, a second inductor and a point, wherein the point is between the capacitor and the first inductor, wherein the capacitor is coupled to the first inductor and the first inductor is coupled to the second inductor, wherein the point is coupled to a variable capacitor and to a corresponding one of the plurality of shunt inductors.
5. The power distributor of claim 1 , further comprising:
an input, wherein the plurality of low frequency paths are coupled to the input, wherein the plurality of low frequency paths are configured to receive the low frequency modified RF signal, wherein each of the plurality of low frequency paths includes a capacitor, a first inductor, and a second inductor, wherein the capacitor is coupled to the first inductor and the first inductor is coupled to the second inductor; and
a plurality of points, wherein each of the plurality of points is between the input and the capacitor of the corresponding one of the plurality of low frequency paths, wherein each of the plurality of shunt inductors is coupled to a corresponding one of the plurality of points.
6. The power distributor of claim 1 , wherein each of the plurality of low frequency paths includes a capacitor, a first inductor, and a second inductor, wherein the capacitor is coupled to the first inductor and the first inductor is coupled to the second inductor.
7. The power distributor of claim 6 , wherein each of the plurality of high frequency RF paths includes a capacitor.
8. The power distributor of claim 7 , wherein the capacitor of each of the plurality of high frequency RF paths is coupled to the second inductor of the corresponding one of the plurality of low frequency paths.
9. The power distributor of claim 1 , wherein the low frequency modified RF signal is received from a low frequency matching network and the high frequency modified RF signal is received from a high frequency matching network.
10. The power distributor of claim 1 , wherein the plurality of output paths includes a switch that is configured to be coupled to an inductor or a dummy load.
11. A power distributor comprising:
a plurality of low frequency paths configured to receive a low frequency modified radio frequency (RF) signal to output a plurality of low frequency RF signals;
a plurality of high frequency paths configured to receive a high frequency modified RF signal to output a plurality of high frequency RF signals, wherein each of the plurality of high frequency paths is coupled to a corresponding one of the plurality of low frequency paths;
a plurality of output paths configured to combine the plurality of low frequency RF signals and the plurality of high frequency RF signals to output a plurality of combined signals to a plurality of plasma processing stations, wherein each of the plurality of output paths is coupled to the corresponding one of the plurality of low frequency paths and a corresponding one of the plurality of high frequency paths; and
a plurality of shunt inductors configured to control a plurality of amounts of current provided to the plurality of plasma processing stations, wherein each of the plurality of shunt inductors is coupled to a corresponding one of the plurality of output paths.
12. The power distributor of claim 11 , wherein each of the plurality of output paths includes a switch, an inductor, and a point between the inductor and the switch, wherein each of the plurality of shunt inductors to the point of the corresponding one of the plurality of output paths.
13. The power distributor of claim 11 , wherein each of the plurality of output paths includes a switch, an inductor, and a plurality of outputs configured to be coupled to the plurality of plasma processing stations, wherein each of the plurality of shunt inductors is coupled to a point between the inductor of the corresponding one of the plurality of output paths and a corresponding one of the plurality of outputs.
14. The power distributor of claim 11 , wherein each of the plurality of low frequency paths includes a capacitor, a first inductor, and a second inductor, wherein the capacitor is coupled to the first inductor and the first inductor is coupled to the second inductor.
15. The power distributor of claim 14 , wherein each of the plurality of high frequency RF paths includes a capacitor.
16. The power distributor of claim 15 , wherein the capacitor of each of the plurality of high frequency RF paths is coupled to the second inductor of the corresponding one of the plurality of low frequency paths.
17. The power distributor of claim 11 , wherein the low frequency modified RF signal is received from a low frequency matching network and the high frequency modified RF signal is received from a high frequency matching network.
18. The power distributor of claim 11 , wherein the plurality of output paths includes a switch that is configured to be coupled to an inductor or a dummy load.
19. A power distributor comprising:
a plurality of low frequency paths configured to receive a low frequency modified radio frequency (RF) signal to output a plurality of low frequency RF signals;
a plurality of high frequency paths configured to receive a high frequency modified RF signal to output a plurality of high frequency RF signals, wherein each of the plurality of high frequency paths is coupled to a corresponding one of the plurality of low frequency paths;
a plurality of output paths configured to combine the plurality of low frequency RF signals and the plurality of high frequency RF signals to output a plurality of combined signals to a plurality of plasma processing stations, wherein each of the plurality of output paths is coupled to the corresponding one of the plurality of low frequency paths and a corresponding one of the plurality of high frequency paths, wherein the plurality of output paths have a plurality of outputs;
a plurality of shunt inductors, wherein each of the plurality of shunt inductors is coupled between an input of the plurality of low frequency paths and a corresponding one of the plurality of outputs of the plurality of output paths to control an amount of current provided to a corresponding one of the plurality of plasma processing stations.
20. The power distributor of claim 19 , wherein each of the plurality of low frequency paths includes a first inductor and a second inductor of a high frequency blocking circuit, wherein the first inductor is coupled at a point to the second inductor of the high frequency blocking circuit, wherein each of the plurality of shunt inductors is coupled to the point of the corresponding one of the plurality of low frequency paths and to a ground connection.
21. The power distributor of claim 19 , wherein each of the plurality of low frequency paths includes a capacitor, a first inductor, a second inductor, and a point, wherein the point is between the capacitor and the first inductor, wherein the capacitor is coupled to the first inductor, and the first inductor is coupled to the second inductor, wherein the point is coupled to a variable capacitor and to a corresponding one of the plurality of shunt inductors.
22. The power distributor of claim 19 , further comprising:
an input, wherein the plurality of low frequency paths are coupled to the input, wherein the plurality of low frequency paths are configured to receive the low frequency modified RF signal, wherein each of the plurality of low frequency paths includes a capacitor, a first inductor, and a second inductor, wherein the capacitor is coupled to the first inductor and the first inductor is coupled to the second inductor; and
a plurality of points, wherein each of the plurality of points is between the input and the capacitor of the corresponding of the plurality of low frequency paths, wherein each of the plurality of shunt inductors is coupled to a corresponding one of the plurality of points.
23. The power distributor of claim 19 , wherein each of the plurality of output paths includes a switch, an inductor, and a point between the inductor and the switch, wherein each of the plurality of shunt inductors to the point of a corresponding one of the plurality of output paths.
24. The power distributor of claim 19 , wherein each of the plurality of output paths includes a switch and an inductor, wherein each of the plurality of shunt inductors is coupled to a point between the inductor of the corresponding one of the plurality of output paths and the corresponding one of the plurality of outputs of the plurality of output paths.