RF Grounding Configuration for Pedestal

Abstract

To provide substrate supports for processing chambers, and RF grounding structures for use therewith.SOLUTION: A chamber body 102 at least partially defines a processing volume therein. A first electrode is disposed in the processing volume. A pedestal 110 is disposed on a side opposite the first electrode 101, . A second electrode 113 is disposed in the pedestal 110. An RF filter 114 is coupled to the second electrode through a conductive rod 107. The RF filter 114 includes a first capacitor 130 coupled to the conductive rod 107 and to ground. The RF filter 114 also includes a first inductor coupled to a feedthrough box. The feedthrough box 125 includes a second capacitor 136 and a second inductor 134 coupled in series. A direct current (DC) power supply 126 for the second electrode is coupled between the second capacitor 136 and the second inductor 134.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present disclosure generally relate to a substrate support for a processing chamber and an RF grounding arrangement for use therewith. [Background technology]

[0002] Radio frequency (RF) power is used in processing substrates, such as semiconductor substrates, for plasma generation, electrostatic chucking, etc. In some processing systems, RF power is supplied to a first electrode and transferred via capacitive coupling to a second electrode, such as a substrate support. The second electrode is coupled to a power source via an electrical connection, allowing the RF power to return to the power source, thus completing the RF circuit.

[0003] In conventional configurations, the RF strap facilitates the flow of RF power through the RF filter to the RF cable. High RF currents and long processing times can cause excessive heating of the RF cable, leading to component degradation or arcing.

[0004] Therefore, there is a need for an improved RF grounding arrangement. Summary of the Invention

[0005] In one embodiment, an apparatus is provided that includes a chamber body at least partially defining a processing region therein. A pedestal is disposed within the processing region. A first electrode is disposed within the processing region opposite the pedestal. A second electrode is disposed within the pedestal. A conductive rod is coupled to the second electrode. A radio frequency (RF) filter includes a first capacitor coupled to the conductive rod and coupled to ground. The RF filter also includes an LC resonant circuit coupled to the conductive rod and a second capacitor coupled to the LC resonant circuit and coupled to ground.

[0006] In another embodiment, an apparatus is provided that includes a chamber body that at least partially defines a processing region therein. A pedestal is disposed within the processing region. A first electrode is disposed within the processing region opposite the pedestal. A second electrode is disposed within the pedestal. A conductive rod is coupled to the second electrode. An RF filter is coupled to the conductive rod. The RF filter includes a first capacitor coupled to the conductive rod and a first inductor coupled to the conductive rod. A feedthrough box includes a second inductor and a second capacitor coupled in series. A power source is coupled to the second electrode through the feedthrough box and the RF filter.

[0007] In yet another embodiment, an apparatus is provided that includes a chamber body at least partially defining a processing region therein. A pedestal is disposed within the processing region. The pedestal includes a substrate support and a shaft coupled to the chamber body to support the substrate support. A first electrode is disposed within the processing region opposite the pedestal. A second electrode is disposed within the pedestal. A conductive rod extends through the shaft of the pedestal and is coupled to the second electrode. An RF filter is disposed within the housing and coupled to the conductive rod. The RF filter includes a first capacitor coupled to the conductive rod and coupled to the housing, and a first inductor coupled to the conductive rod. A feedthrough box includes a second inductor and a second capacitor coupled in series. A cable is coupled to the first inductor and to the second inductor. A power source is coupled to the second electrode through the feedthrough box and the RF filter. The power source is coupled between the second inductor and the second capacitor.

[0008] In order that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments and therefore should not be considered limiting of the scope thereof, as other equally effective embodiments may also be permissible. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a processing chamber according to one aspect of the present disclosure. [Figure 2] FIG. 1 illustrates a pedestal and RF grounding configuration according to one embodiment of the present disclosure. [Figure 3] Diagram showing a conventional RF grounding configuration utilizing a bottom tuner DETAILED DESCRIPTION OF THE INVENTION

[0010] For ease of understanding, wherever possible, like reference numerals are used to designate like elements common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0011] Embodiments of the present disclosure generally relate to a substrate support for a processing chamber and an RF grounding configuration for use therewith. A method for grounding RF currents is also described. A chamber body at least partially defines a processing region therein. A first electrode is disposed within the processing region. A pedestal is disposed opposite the first electrode. A second electrode is disposed within the pedestal. An RF filter is coupled to the second electrode via a conductive rod. The RF filter includes a first capacitor coupled to the conductive rod and connected to ground. The RF filter also includes a first inductor coupled to a feedthrough box. The feedthrough box includes a second capacitor and a second inductor coupled in series. A direct current (DC) power source for the second electrode is coupled between the second capacitor and the second inductor.

[0012] 1 illustrates a processing chamber 100 according to one embodiment of the present disclosure. The processing chamber 100 includes a chamber body 102 that at least partially defines a processing region 104 therein. A pedestal 110 is disposed within the processing region 104. An RF grounding arrangement 120 is coupled to the pedestal 110. An electrode 101, such as a showerhead, is disposed opposite the pedestal 110. An RF power source 106 is coupled to the electrode 101 to facilitate the generation of a plasma within the processing chamber 100. Power from the RF power source 106 is capacitively coupled to the pedestal 110 during processing.

[0013] The pedestal 110 includes a substrate support 111 disposed on the upper end of a support shaft 112. The substrate support 111 is formed of a ceramic material such as aluminum nitride, while the support shaft 112 is formed of a metal such as aluminum or a ceramic such as aluminum nitride. A resistive heating element (not shown) may optionally be disposed within the substrate support 111 to facilitate temperature regulation of the substrate support 111. An electrode 113, such as an RF mesh, may be disposed within the substrate support 111 to facilitate plasma generation within the processing chamber 100. A conductive rod 107 (e.g., an RF rod) is coupled to the electrode 113 and extends through the shaft 112 to an RF filter 114. The RF filter 114 can be configured as a pass filter (e.g., to pass desired RF frequencies while blocking undesired frequencies), as a block filter (e.g., configured to limit or prevent RF energy conducted through the plasma from exiting the processing chamber), or to combine RF and DC power onto a single electrode, such as the electrode 113 or another electrode in the pedestal 110.

[0014] The RF filter 114 includes a first capacitor 130 and a first inductor 132 disposed therein. The first capacitor 130 is disposed between and electrically connects the RF rod 107 and the conductive housing 114a of the RF filter 114. In this manner, the RF current conducted by the RF rod 107 is conducted through the first capacitor 130 to the conductive (e.g., grounded) housing 114a and then to the conductive (e.g., grounded) inner surface of the chamber body 102 of the processing chamber 100. The RF current can then be returned to the ground of the RF generator 106. The first inductor 132 is coupled in series between the electrode 113 and the RF cable 117. The first inductor 132 facilitates blocking residual RF current flowing through the RF cable 117. In one example, the 13.56 MHz RF current passing through the RF filter 114 is approximately 2.5 A (rms) in the RF grounding configuration 120.

[0015] The combination of the first capacitor 130 and the first inductor 132 reduces the flow of RF current through the RF cable 117 compared to conventional approaches by directing the flow of RF power current to the interior surface of the chamber body 102. In one example, the flow of RF power current through the RF cable 117 is reduced by approximately 90 percent (%) compared to conventional approaches. Therefore, arcing and component degradation within the processing chamber 100 are reduced. Additionally, in the embodiments disclosed herein, the RF cable 117 draws less than 3 A (rms), which results in the RF cable operating at a lower temperature compared to conventional approaches. Because the RF cable 117 operates at a lower temperature, inadvertent or unwanted reflow soldering of electrical connections is reduced. Furthermore, arcing within the processing chamber 100 is reduced.

[0016] The RF cable 117 is also coupled to an electrostatic chuck (ESC) feedthrough box 125. A high voltage direct current (HV DC) power supply 126 inputs power to the ESC feedthrough box 125 to facilitate operation of an electrostatic chuck (not shown) disposed within the pedestal 110. The ESC feedthrough box 125 facilitates the conduction of HV DC current through the RF cable 117, through the RF filter 114, to the pedestal 110 and to the electrode 113.

[0017] The ESC feedthrough box 125 includes a capacitor 136 and an inductor 134 arranged in series between the HV DC power supply 126 and the RF cable 117. The ESC feedthrough box 125 is significantly simplified compared to conventional approaches, for example, by omitting a variable capacitor (e.g., traditionally referred to as a "bottom tuner"). The feedthrough box 125 is coupled to ground.

[0018] FIG. 2 illustrates a pedestal 110 and an RF grounding configuration 220 coupled thereto according to one embodiment of the present disclosure. The RF grounding configuration 220 can be used in place of the RF grounding configuration 120 shown in FIG. 1. The RF grounding configuration 220 includes an RF filter 214. The RF filter 214 includes a capacitor 230 arranged in series with an LC resonant circuit 240. The LC resonant circuit 240 includes a capacitor 234 and an inductor 232 arranged in parallel with each other. An ESC cable 236 conducts HV DC power from the HV DC power source 126 through the RF cable 117 to the pedestal 110. A capacitor 238 couples the RF cable 117 to the conductive housing 214a of the RF filter 214.

[0019] In the example of FIG. 2 , RF power, for example at a frequency of 13.56 MHz, is coupled through a plasma in a processing chamber (such as processing chamber 100) to an RF mesh or another electrode in pedestal 110. The RF mesh or other electrode is coupled to ground through RF rod 107 via capacitor 230. The capacitance of capacitor 230 is selected so that capacitor 230 provides a virtual ground for the 13.56 MHz RF current. Capacitor 230 is also selected so that the heater-to-ground impedance matches a known value. LC resonant circuit 240 facilitates blocking of residual RF current flowing through RF cable 117. LC resonant circuit 240 provides a higher impedance than first inductor 132 compared to RF grounding configuration 120, as shown in FIG. 1 . Capacitor 238 facilitates grounding of the RF voltage across RF cable 117 so that the voltage (and therefore current) across RF cable 117 is zero or near zero. In one example, the RF voltage is less than 10 V (rms). In one example, the 13.56 MHz RF current measured through the sensor at the output of the RF filter 214 is about 0.5 A (rms).

[0020] FIG. 3 illustrates a conventional RF grounding configuration 320. The conventional RF grounding configuration 320 is coupled to a pedestal 310. The pedestal may be disposed in a processing chamber, such as the processing chamber 100 described with reference to FIG. 1. The RF grounding configuration 320 includes an RF filter 314 and a bottom tuner 340. An RF rod 312 extends through the shaft of the pedestal 310 to the RF filter 314. The RF filter 314 includes an RF strap 316 therein that couples the RF rod 312 to an RF cable 318. The RF cable 318 is connected to the bottom tuner 340. The bottom tuner 340 includes a variable capacitor 342 and an inductor 344 arranged in parallel with a fixed capacitor 348 and an inductor 346. In the conventional RF grounding configuration 320, all RF current conducted from the pedestal 310 is grounded to the body of the processing chamber through the bottom tuner 340, which is then connected to the ground of the RF generator. In such a configuration, the 13.56 MHz RF current inside bottom tuner 340 is approximately 25 A (rms), which causes the above-mentioned problem.

[0021] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the claims that follow.

Claims

1. The pedestal and an electrode disposed within the pedestal; a conductive rod coupled to the electrode; a radio frequency (RF) filter disposed within the housing configured to be coupled to ground, a first capacitor coupled to the conductive rod, coupled to the housing, and configured to be coupled to ground; an LC resonant circuit coupled to the conductive rod; and a second capacitor coupled to the LC resonant circuit, coupled to the housing, and configured to be coupled to ground; a radio frequency (RF) filter comprising: a direct current (DC) power source coupled to the electrodes via the LC resonant circuit and the conductive rod; An apparatus comprising:

2. The apparatus of claim 1 , wherein the LC resonant circuit and the second capacitor are downstream of the first capacitor.

3. The apparatus of claim 1 , wherein the LC resonant circuit includes a third capacitor and an inductor coupled in parallel.

4. The device of claim 1 , wherein the housing is an enclosure.

5. The device of claim 1 , wherein the conductive rod extends through a top portion of the housing.

6. The apparatus of claim 5 , wherein the pedestal comprises a substrate support and a shaft coupled to the substrate support.

7. The apparatus of claim 6 , wherein the conductive rod extends through the shaft of the pedestal.

8. a chamber body at least partially defining a processing region; a pedestal disposed within the processing region, the pedestal comprising a substrate support and a shaft coupled to the substrate support; a first electrode disposed within the processing region opposite the pedestal; a second electrode disposed within the pedestal; a conductive rod extending through the shaft of the pedestal and coupled to the second electrode; a radio frequency (RF) filter disposed within the housing and coupled to the conductive rod, a first capacitor coupled to the conductive rod and coupled to the housing; an LC resonant circuit coupled to the conductive rod; and a second capacitor coupled to the LC resonant circuit and coupled to the housing; an RF filter comprising: a direct current (DC) power source coupled to the second electrode via the LC resonant circuit and the conductive rod; An apparatus comprising:

9. an RF cable extending at least partially between the housing and the power source and disposed in series with the LC resonant circuit; The apparatus of claim 8 further comprising:

10. The apparatus of claim 9 , wherein the second capacitor couples the RF cable to the housing.

11. 9. The apparatus of claim 8, wherein the housing is coupled to ground, the conductive rod extends through a top of the housing, and the housing is conductive.

12. The apparatus of claim 11 , wherein the housing extends at least partially through the chamber body, the housing enclosing the first capacitor, the LC resonant circuit, and the second capacitor.

13. 1. An apparatus for processing a substrate, comprising: a pedestal having a substrate support and a shaft; an electrode disposed within the pedestal; a conductive rod coupled to the electrode; an RF filter coupled to the conductive rod, a housing coupled to ground; a first capacitor coupled between the conductive rod and the housing; and a first inductor coupled to the conductive rod; an RF filter comprising: a feedthrough box coupled to ground, the feedthrough box having a second inductor and a second capacitor coupled in series disposed therein, the second capacitor coupled between the second inductor and the feedthrough box; an RF cable extending at least partially between the housing and the feedthrough box and disposed in series with the RF filter and the second inductor of the feedthrough box; a direct current (DC) power source coupled to the electrode through the second inductor and the RF filter; An apparatus comprising:

14. 14. The device of claim 13, wherein the conductive rod extends through the shaft and through a top of the housing, the housing being conductive.

15. A second electrode; an RF source coupled to the second electrode; The apparatus of claim 14 further comprising:

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