Method of processing a workpiece in a plasma reactor with independent wafer edge process gas injection

• US 7,879,250 B2
• Filed: 09/05/2007
• Issued: 02/01/2011
• Est. Priority Date: 09/05/2007
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Todorow, Valentin N., Willwerth, Michael D., Paterson, Alexander M., Palagashvili, David, Katz, Dan
• Primary Examiner(s): CULBERT, ROBERTS P
• Application Number:
  US11/899,613
• Publication Number:
  US 20090057269A1
• Time in Patent Office: 1,245 Days
• Field of Search: 216/67, 438/710, 118/723.I, 156/345.48
• US Class Current: 216/67
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

The disclosure concerns a method of processing a workpiece or in a plasma reactor chamber, using independent gas injection at the wafer edge.

Claims

1. A method of performing a plasma etch process on a workpiece surface of a workpiece comprising a surface material to be etched, comprising:

placing the workpiece on a workpiece support in a chamber of the plasma reactor;

introducing through a ceiling gas disperser a first process gas comprising an etchant species capable of causing etching of said surface material in a plasma, said ceiling gas disperser comprising mutually concentric inner and outer gas dispersers;

generating a plasma in said chamber by coupling RF power into said chamber;

controlling etch rate distribution across said workpiece surface by adjusting respective flow rates of said first process gas through respective ones of said inner and outer gas dispersers;

reducing etch rate at an edge periphery of said workpiece surface relative to etch rate across a remainder of said workpiece surface by injecting a polymerizing gas through a workpiece support gas disperser provided on said workpiece support and facing said edge periphery, said workpiece support gas disperser defining a polymerizing gas injection pattern directed toward said edge periphery of said workpiece surface and confined generally to said edge periphery.

2. The method of claim 1 wherein said edge periphery is limited to on the order of 1% of an outer portion of a diameter of said workpiece surface.

3. The method of claim 1 wherein injecting a polymerizing gas through a workpiece support gas disperser comprises supplying said polymerizing gas through gas flow channels inside a portion of said workpiece support.

4. The method of claim 3 wherein injecting a polymerizing gas further comprises conducting polymerizing gas received from said gas flow channels through a process ring on said workpiece support surrounding said edge periphery of said workpiece surface.

5. The method of claim 2 further comprising limiting gas flow rate through said workpiece support gas disperser to confine the effect of the polymerizing gas to edge periphery of said workpiece surface.

6. The method of claim 1 wherein said surface material to be etched comprises one of silicon or polysilicon, said first process gas comprises one of HBr or Cl₂, and said polymerizing gas comprises one of CH₂F₂ or CHF₃.

7. The method of claim 4 wherein said injecting a polymerizing gas comprises injecting said polymerizing gas through a slit injector surrounding said edge periphery of said workpiece and facing said edge periphery and supported on said process ring.

8. The method of claim 7 wherein said slit injector comprises a thin opening extending circumferentially around said edge periphery of said workpiece surface and extending from a lower boundary coplanar with said workpiece surface to an upper boundary above said workpiece surface.