Plasma energy control by inducing plasma instability

• US 6,558,564 B1
• Filed: 04/05/2000
• Issued: 05/06/2003
• Est. Priority Date: 04/05/2000
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Zawalski, Wade, Loewenhardt, Peter K.
• Primary Examiner(s): GOUDREAU, GEORGE A
• Application Number:
  US09/543,392
• Time in Patent Office: 1,126 Days
• Field of Search: 438/714, 438/729, 216/67, 216/68, 216/69, 216/71, 427/569
• US Class Current: 216/67
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence

Abstract

In the present invention, electron temperature is controlled by modifying the power delivered to the plasma by inducing or enhancing natural instabilities between the plasma and the power source. As a result, no pulse modulation of the RF power or RF generator is required. The instability is enhanced until the desired reduction in electron temperature has been achieved. In accordance with the invention, there are several modes for inducing such a natural instability.

Claims

1. A method of reducing electron temperature in a plasma reactor having an RF power control system, said method comprising increasing instabilities between a plasma within the reactor and said control system until said electron temperature is reduced by a desired amount, wherein the step of increasing instabilities comprises introducing electrons into said plasma from a separate source.

2. The method of claim 1 wherein the step of introducing electrons comprises directing an electron beam into said reactor.

3. A method of controlling electron temperature in a plasma reactor having an RF power control system, said method comprising:

providing a correlation between values of a parameter affecting instability of a plasma in said reactor and electron temperature;

selecting a desired electron temperature;

determining from said correlation a value of said parameter corresponding to said desired electron temperature;

changing the value of said parameter to said corresponding value;

wherein the step of changing said value of said parameter increases instabilities between a plasma within the reactor and said control system until said electron temperature is reduced to said desired electron temperature; and

wherein said parameter is electron current flow into said chamber from a source and the step of increasing instabilities comprises increasing said electron current flow.

4. The method of claim 3 wherein said electron current flow comprises an electron beam directed into said reactor.