Electron beam enhanced surface wave plasma source

• US 20080060759A1
• Filed: 09/12/2006
• Published: 03/13/2008
• Est. Priority Date: 09/12/2006
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Chen, Lee, Moroz, Paul
• Granted Patent: US 7,998,307 B2
• Time in Patent Office: Days
• US Class Current: 156/345.41
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/3222 Antennas
• CPC Class Codes: H01J 37/3233 using charged particles

Abstract

A plasma processing system is described for generating plasma with a ballistic electron beam using a surface wave plasma (SWP) source, such as a radial line slot antenna (RLSA) during semiconductor device fabrication. The antenna comprises a resonator plate having a partially open, electrically conductive layer coupled to a surface of the resonator plate. For example, the electrically conductive layer is formed at an interface between the resonator plate and the plasma.

Claims

1. A plasma processing system configured to etch a substrate, comprising:

a plasma processing chamber configured to facilitate the formation of plasma from process gas introduced therein;

a substrate holder coupled to said plasma processing chamber and configured to support said substrate;

an electromagnetic (EM) wave launcher coupled to said plasma processing chamber and configured to couple EM energy in a desired EM wave mode to a plasma by generating a surface wave on a plasma surface of said EM wave launcher adjacent said plasma;

a power coupling system coupled to said EM wave launcher and configured to provide said EM energy to said EM wave launcher for forming said plasma;

an electrically conductive layer coupled to said plasma surface of said EM wave launcher, wherein said electrically conductive layer comprises a plurality of openings to permit the passage of EM energy there-through; and

a direct current (DC) power system coupled to said electrically conductive layer and configured to couple a DC voltage to said electrically conductive layer in order to form a ballistic electron beam.

2. The plasma processing system of claim 1, wherein said power coupling system comprises a microwave power coupling system comprising:

a microwave source configured to produce microwave energy at 2.45 GHz;

a waveguide coupled to an outlet of said microwave source;

an isolator coupled to said waveguide and configured to prevent propagation of microwave energy back to said microwave source; and

a coaxial converter coupled to said isolator and configured to couple said microwave energy to a coaxial feed, wherein said coaxial feed is further coupled to said EM wave launcher.

3. The plasma processing system of claim 1, wherein:

said power coupling system comprises a coaxial feed for coupling EM energy to said EM wave launcher;

said EM launcher comprises a slot antenna with one end coupled to an inner conductor of said coaxial feed and another end coupled to an outer conductor of said coaxial feed; and

said slot antenna includes one or more slots configured to couple said EM energy from a first region above said slot antenna between said inner conductor and said outer conductor to a second region below said slot antenna.

4. The plasma processing system of claim 3, wherein said EM wave launcher further comprises:

a slow wave plate positioned in said first region and configured to reduce the effective wavelength of said EM energy relative to the wavelength in free space; and

a resonator plate positioned in said second region and having a lower surface of said resonator plate including said plasma surface of the EM wave launcher.

5. The plasma processing system of claim 1, wherein said DC power system is configured to couple DC power ranging in voltage from approximately −

2000 V to approximately 1000 V.

6. The plasma processing system of claim 5, wherein said DC power system is configured to couple DC power having a negative polarity and the absolute value of the DC voltage is greater than or equal to approximately 500 V.

7. The plasma processing system of claim 1, wherein said electrically conductive layer is deposited on the plasma surface of said resonator plate and a protective layer of material is deposited or fused over said deposited electrically conductive layer.

8. The plasma processing system of claim 1, wherein said electrically conductive layer is embedded within the surface layer of said plasma surface of said resonator plate.

9. The plasma processing system of claim 1, wherein said resonator plate comprises a high dielectric constant (high-k) material, said high dielectric constant material having a dielectric constant greater than a value of 4.

10. The plasma processing system of claim 1, wherein said electrically conductive layer is fabricated from a metal.

11. The plasma processing system of claim 1, wherein said electrically conductive layer is fabricated from hafnium, zirconium, titanium, or doped silicon, or a combination of two or more thereof.

12. The plasma processing system of claim 1, wherein said plurality of openings in said electrically conductive layer are uniformly distributed.

13. The plasma processing system of claim 1, wherein said plurality of openings in said electrically conductive layer are non-uniformly distributed.

14. The plasma processing system of claim 1, further comprising:

a grid coupled to said plasma processing chamber and configured to separate said plasma processing chamber into a first chamber portion configured to receive a first gas for providing a plasma space and a second chamber portion configured to receive a second gas for providing a process space having process chemistry to treat said substrate,

wherein said grid is located between said plasma space and said process space, and configured to permit the diffusion of said plasma between said plasma space and said process space in order to form said process chemistry from said process gas.

15. The plasma processing system of claim 14, wherein said grid comprises one or more passageways for coupling said plasma space to said process space.

16. The plasma processing system of claim 15, wherein said one or more passageways form a rectangular pattern.

17. The plasma processing system of claim 15, wherein said one or more passageways form a circular pattern.

18. The plasma processing system of claim 14, wherein said grid is coupled to a temperature control system configured to control the temperature of the grid and said temperature control system comprises one or more fluid channels in said grid configured to flow a heat transfer fluid.

19. The plasma processing system of claim 18, wherein said one or more fluid channels comprises a plurality of fluid channels configured to provide spatial temperature control of said grid in order to control uniformity of said process performed in said processing system.

20. The plasma processing system of claim 14, wherein said grid comprises a gas injection grid configured to inject at least one of said first gas or said second gas and said gas injection grid includes a first gas channel array configured to provide multiple zones for injecting said first gas into said plasma space to control uniformity of said process performed in said processing system.

21. The plasma processing system of claim 20, wherein said gas injection grid includes a first gas channel array configured to provide multiple zones for injecting said first gas to control uniformity of said process performed in said processing system.