Methods And Apparatus For Generating Strongly-Ionized Plasmas With Ionizational Instabilities

Abstract

A plasma generator includes a chamber for confining a feed gas. An anode is positioned inside the chamber. A cathode assembly is positioned adjacent to the anode inside the chamber. A pulsed power supply comprising at least two solid state switches and having an output that is electrically connected between the anode and the cathode assembly generates voltage micropulses. A pulse width and a duty cycle of the voltage micropulses are generated using a voltage waveform comprising voltage oscillation having amplitudes and frequencies that generate a strongly ionized plasma.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This patent application is a continuation-in-part of U.S. Patent Application Ser. No. 12 / 651,368, filed Dec. 31, 2009, entitled “Methods and Apparatus for Generating Strongly-Ionized Plasmas with Ionizational Instabilites,” which is a continuation of U.S. patent application Ser. No. 11 / 738,491, filed Apr. 22, 2007, entitled “Methods and Apparatus for Generating Strongly-Ionized Plasmas with Ionizational Instabilites,” now U.S. Pat. No. 7,663,319 which claims priority to U.S. Provisional Patent Application 60 / 745,398, filed Apr. 22, 2006, And which is a continuation-in-part of U.S. patent application Ser. No. 11 / 376,036, filed Mar. 15, 2006, entitled “Methods and Apparatus for Generating Strongly-Ionized Plasmas with Ionizational Instabilites,” now U.S. Pat. No. 7,345,429, which is a continuation of U.S. patent application Ser. No. 10 / 708,281 filed Feb. 22, 2004, entitled “Methods and Apparatus for Generating Strongly-Ionized Plasmas with ...

AI Technical Summary

Benefits of technology

The patent text describes a method and apparatus for generating a strong plasma in a plasma sputtering chamber using a pulsed direct current (DC) power supply. The invention aims to improve the plasma density while reducing temperature gradients and non-uniform plasma density that can cause non-uniform plasma process. The invention also aims to reduce the likelihood of arcing and contamination of the work piece. The technical effects of the invention include increased plasma density, reduced temperature gradients, and reduced likelihood of arcing and contamination.

Problems solved by technology

Applying high electrical currents through a plasma can result in overheating the electrodes as well as overheating the work piece in the chamber.

However, the cooling can cause temperature gradients in the chamber.

These temperature gradients can cause non-uniformities in the plasma density which can cause non-uniform plasma process.

However, pulsed DC power systems are prone to arcing at plasma ignition and plasma termination, especially when working with high-power pulses.

Arcing can result in the release of undesirable particles in the chamber that can contaminate the work piece.

However, the electrode voltage is limited in many applications because high electrode voltages can effect the properties of films being deposited or etched.

In addition, high electrode voltages can also cause arcing which can damage the electrode and contaminate the work piece.

Images