RF Bus and RF Return Bus for Plasma Chamber Electrode

• US 20100206483A1
• Filed: 02/13/2010
• Published: 08/19/2010
• Est. Priority Date: 02/13/2009
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Anwar, Suhail, White, John M., Tiner, Robin L., Kudela, Jozef, Sorensen, Carl A.
• Granted Patent: US 8,992,723 B2
• Time in Patent Office: Days
• US Class Current: 156/345.340
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge

Abstract

For coupling RF power from an RF input of a plasma chamber to the interior of a plasma chamber, an RF bus conductor is connected between the RF input and a plasma chamber electrode. In one embodiment, an RF return bus conductor is connected to an electrically grounded wall of the chamber, and the RF bus conductor and the RF return bus conductor have respective surfaces that are parallel and face each other. In another embodiment, the RF bus conductor has a transverse cross section having a longest dimension oriented perpendicular to the surface of the plasma chamber electrode that is closest to the RF bus conductor.

Claims

2. Apparatus for coupling RF power from an RF input to the interior of a plasma chamber, comprising:

a plasma chamber having one or more electrically grounded chamber walls and having a plasma chamber electrode that is insulated from electrical ground;

an RF bus conductor that is electrically connected to the RF input and is electrically connected to one or more connection points on the plasma chamber electrode, wherein the RF bus conductor includes a first surface; and

an RF return bus conductor that is electrically connected to one of the electrically grounded chamber walls, wherein the RF return bus conductor includes a second surface;

wherein the first surface is parallel to and faces the second surface; and

wherein the first and second surfaces are separated by a spacing that is less than the width of the first surface in any direction and is less than the width of the second surface in any direction.

1. The apparatus of claim 2, wherein:

the first and second surfaces are separated by a spacing that is less than the spacing between the RF bus conductor and any of the electrically grounded chamber walls that are parallel to the first surface.

4. The apparatus of claim 2, wherein:

the capacitance between the RF bus conductor and the RF return bus conductor is greater than the capacitance between the RF bus conductor and the chamber wall.

5. The apparatus of claim 2, wherein:

the plasma chamber electrode includes a showerhead adapted for dispensing gas into the Plasma chamber.

6. The apparatus of claim 2, wherein the plasma chamber electrode comprises:

a back wall having a gas inlet conduit;

a showerhead positioned below the back wall; and

an electrical conductor connected between back wall and the showerhead;

wherein said connection points are on the back wall.

7. The apparatus of claim 6, wherein:

none of the connection points are at the center of the back wall.

8. The apparatus of claim 2, wherein:

the plasma chamber electrode is positioned so as to capacitively couple RF power into the plasma chamber.

9. The apparatus of claim 2, wherein:

the plasma chamber electrode includes first and second connection points that are separated by a distance;

a portion of the RF bus conductor includes first and second connection points that are respectively connected to the first and second connection points on the plasma chamber electrode;

said portion of the RF bus conductor has a length extending between the first and second connection points of the RF bus conductor that is greater than one-half the distance between the first and second connection points of the plasma chamber electrode; and

the RF return bus conductor extends parallel to the entire length of said portion of the RF bus conductor.

10. The apparatus of claim 2, further comprising:

an RF impedance matching network having an output connected to said RF input so as to provide an electrical connection path from the output of the RF impedance matching network to said one or more connection points on the plasma chamber electrode;

wherein at least one-half the length of the electrical connection path extending from the output of the RF impedance matching network to one of said connection points includes the RF bus conductor.

11. The apparatus of claim 2, further comprising a capacitor connected between an RF bus conductor and one of the connection points.

3. Apparatus for coupling RF power from an RF input to the interior of a plasma chamber, comprising:

a plasma chamber having one or more electrically grounded chamber walls and having a plasma chamber electrode that is insulated from electrical ground;

an RF bus conductor that is electrically connected to the RF input and is electrically connected to one or more connection points on the plasma chamber electrode, wherein the RF bus conductor includes a first surface; and

an RF return bus conductor that is electrically connected to one of the electrically grounded chamber walls, wherein the RF return bus conductor includes a second surface;

wherein the first surface is parallel to and faces the second surface; and

wherein the RF bus conductor includes a curved portion so that the first surface is not planar, the RF return bus conductor includes a curved portion so that the second surface is not planar, and the curved portion of the RF bus conductor is aligned with the curved portion of the RF return bus conductor so that the first surface is parallel to the second surface.

12. Apparatus for coupling RF power from an ungrounded RF input connection to a plasma chamber, comprising:

a plasma chamber electrode that is insulated from electrical ground; and

an RF bus conductor that is electrically connected between said ungrounded RF input connection and the plasma chamber electrode;

wherein the RF bus conductor has a transverse cross section having a longest dimension oriented perpendicular to the surface of the plasma chamber electrode that is closest to the RF bus conductor.

13. The apparatus of claim 12, further comprising:

an electrical conductor connected between the RF bus conductor and the ungrounded RF input connection;

wherein the RF bus conductor is not directly connected to the ungrounded RF input connection.

14. The apparatus of claim 12, wherein:

the plasma chamber electrode comprises a gas inlet manifold having a showerhead and a back wall; and

the RF bus conductor is electrically connected to a connection point on the back wall.