Coupled microwave ECR and radio-frequency plasma source for plasma processing

• US 5,292,370 A
• Filed: 08/14/1992
• Issued: 03/08/1994
• Est. Priority Date: 08/14/1992
• Status: Expired due to Fees

• Current Assignee: United States Department of Energy
• Original Assignee: Martin Marietta Energy Systems, Inc.
• Inventors: Haselton, Halsey H., Tsai, Chin-Chi
• Primary Examiner(s): Thomas, Tom
• Assistant Examiner(s): BASKIN, JONATHAN
• Application Number:
  US07/930,590
• Time in Patent Office: 571 Days
• Field of Search: 118/723, 156/345, 315/111.21, 315/111.41, 315/111.71, 427/569, 427/575
• US Class Current: 118/723.0MP
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32678 Electron cyclotron resonance

Abstract

In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm² at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance.

Claims

1. In a plasma processor incorporating an electron cyclotron resonance (ECR) microwave plasma source to initiate and feed the radio-frequency (RF) plasma of a RF plasma source in a common vacuum chamber, the improvement comprising:

said microwave plasma source including static magnetic field producing means located at the walls of said microwave source for producing an ECR zone over a maximum extent of inner wall area, said microwave source operating at ECR and producing a uniform ECR microwave plasma over at least a 1000 cm² area at a pressure below 0.1 mtorr;

said RF plasma source including static magnetic field means for producing ECR zones within said RF plasma source; and

a magnetic filter between said plasma sources, said filter including static magnetic field means and electrically biased plates for affecting said ECR microwave plasma and said RF plasma;

said static magnetic field means of said filter also producing ECR zones within said ECR microwave plasma source and said RF plasma source.

2. In the plasma processor of claim 1, the walls of said microwave plasma source and said RF plasma source being right circular cylindrical;

said magnetic filter having a right circular cylindrical geometry; and

said ECR microwave plasma source, said magnetic filter, and said RF plasma source being arranged along a common axis.

3. In the plasma processor of claim 1, said RF plasma source being right circular cylindrical;

said magnetic filter having a circumferential geometry, and being disposed coaxially about said RF plasma source; and

said ECR microwave plasma source having a circumferential geometry, and being disposed coaxially about said magnetic filter.

4. A plasma processor according to claim 3 further including a second ECR microwave plasma source, the walls of said second ECR microwave plasma source being right circular cylindrical, said plasma processor and said second ECR microwave plasma source being arranged along a common axis, and said second ECR microwave plasma source providing a second microwave feed into said RF plasma source for added flexibility in plasma processing.

5. In the plasma processor of claim 1, said magnetic filter including bar-shaped magnet column assemblies mounted in a metal ring, said metal ring disposed between two slotted plates, said ring and said slotted plates being capable of independent electrical biasing through individual power supplies.

6. The plasma processor of claim 1 wherein said microwave plasma source is turned on and said RF plasma source is turned off.

7. The plasma processor of claim 1 wherein said microwave plasma source is turned off and said RF plasma source is turned on.

8. The plasma processor of claim 1 wherein said microwave plasma source is turned on and said RF plasma source is turned on.