Exhaust assembly for a plasma processing system

• US 8,012,305 B2
• Filed: 08/22/2008
• Issued: 09/06/2011
• Est. Priority Date: 08/11/2006
• Status: Expired due to Fees

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Takahashi, Hiroyuki
• Primary Examiner(s): Kackar; Ram N
• Assistant Examiner(s): Chandra; Satish
• Application Number:
  US12/196,670
• Publication Number:
  US 20080295964A1
• Time in Patent Office: 1,110 Days
• Field of Search: 118/715, 118/723.E, 118/723.AN, 118/728, 118/732, 156/345.28, 156/345.43, 156/345.48, 216/61
• US Class Current: 156/345.28
• CPC Class Codes: H01J 37/32844 Treating effluent gases
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: Y02C 20/30 of perfluorocarbons [PFC], hydrofluorocarbons [HFC] or sulfur hexafluoride [SF6]
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

An exhaust assembly is described for use in a plasma processing system, whereby secondary plasma is formed in the exhaust assembly between the processing space and chamber exhaust ports in order to reduce plasma leakage to a vacuum pumping system, or improve the uniformity of the processing plasma, or both. The exhaust assembly includes a powered exhaust plate in combination with a ground electrode is utilized to form the secondary plasma surrounding a peripheral edge of a substrate treated in the plasma processing system.

Claims

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

a plasma processing chamber having a chamber wall enclosing a process space and configured to facilitate the formation of a processing plasma in the process space;

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

a plasma generation system coupled to the plasma processing chamber and configured to form said processing plasma from a process gas in the process space adjacent said substrate;

a vacuum pumping system coupled to the plasma processing chamber and configured to evacuate said process gas from the process space;

an exhaust assembly coupled to the plasma processing chamber around said substrate holder and separating said process space from a pumping space coupled to the vacuum pumping system;

an electrical power source coupled to the exhaust assembly and configured to form a secondary plasma in order to alter said processing plasma;

the exhaust assembly comprising;

a first annular exhaust plate surrounding said substrate holder and extending between the substrate holder and the chamber wall to separate the process space from the said pumping space;

electrical insulation members coupled to the first exhaust plate and configured to insulate the first exhaust plate from the substrate holder and the chamber wall; and

a second annular exhaust plate surrounding the substrate holder and extending between the substrate holder and the chamber wall between the first annular exhaust plate and said pumping space to form a secondary plasma space between the first exhaust plate and the second exhaust plate;

the first exhaust plate having a plurality of openings therethrough to allow passage of said process gas therethrough from the processing chamber to said second exhaust plate and the second exhaust plate having a plurality of openings therethrough to allow passage of said process gas therethrough from the secondary plasma space to said pumping space;

wherein the first exhaust plate is coupled to the electrical power source and the second exhaust plate is coupled to electrical ground;

wherein the secondary plasma is being formed in the secondary plasma volume between said first exhaust plate and the second exhaust plate;

a controller programmed to control said plasma processing system to perform the following steps;

disposing a substrate on the substrate holder in the plasma processing chamber;

forming a processing plasma in a process space above and adjacent the substrate disposed on the substrate holder in the plasma processing chamber using the plasma generation system coupled to said plasma processing chamber;

coupling electrical power to the exhaust assembly within said plasma processing chamber that substantially surrounds said substrate holder and separates said process space from a pumping space coupled to the vacuum pumping system, thereby forming a secondary plasma in order to alter said processing plasma to thereby expose said substrate to said altered processing plasma;

said first exhaust plate having a plurality of openings to allow passage of process gas therethrough;

said second exhaust plate being parallel with said first exhaust plate and below said first exhaust plate, said second exhaust plate having a plurality of openings to allow passage of process gas therethrough; and

said controller is programmed to control the plasma processing system to couple electrical power between the first exhaust plate and a ground electrode that is coupled to an electrical ground, and forming the secondary plasma between the first exhaust plate and the ground electrode.

2. The system of claim 1, wherein said exhaust assembly is configured to improve the spatial uniformity of said processing plasma.

3. The plasma processing system of claim 1, wherein said first exhaust plate is fabricated from aluminum and has at least one surface thereon that is anodized or coated.

4. The plasma processing system of claim 3, wherein said at least one surface of said first exhaust plate is coated with aluminum oxide or yttrium oxide.

5. The plasma processing system of claim 1, wherein said second exhaust plate is fabricated from aluminum and has at least one surface thereon that is anodized or coated.

6. The plasma processing system of claim 5, wherein said at least one surface of said second exhaust plate is coated with aluminum oxide or yttrium oxide.

7. The plasma processing system of claim 1, wherein said plasma generation system comprises a capacitively coupled plasma (CCP) system, an inductively coupled plasma (ICP) system, a transformer coupled plasma (TCP) system, an electron cyclotron resonance (ECR) plasma system, a helicon wave plasma system, a surface wave plasma system, or a slotted plane antenna (SPA) plasma system, or a combination of two or more thereof.

8. The plasma processing system of claim 1, wherein said electrical power source comprises a DC power source or an AC power source or both.

9. The plasma processing system of claim 1, wherein said electrical power source comprises an RF power source.