System and method for detecting endpoint in plasma processing
AssigneeForth-Rite Technologies
InventorsTerry R. Turner, Jerome R. Cannon
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Abstract
A plasma processing control method for detecting an endpoint and controlling plasma processing is disclosed. The plasma processing control method includes tracking one or more harmonics that are produced due to nonlinearity of an impedance of a plasma environment. The one or more harmonics are associated with voltage, current, or a combination thereof. The plasma processing control method further includes analyzing the tracked one or more harmonics and detecting an endpoint of plasma processing based on the analysis of the tracked one or more harmonics. Thereafter, the plasma processing control method includes stopping the plasma processing based on the detected endpoint.
Claims20
A plasma processing control system for detecting endpoint and controlling an in-situ plasma processing, the plasma processing control system comprising:
- a power generator to generate an energy for ionizing a gas in a plasma processing chamber in which a substrate to be plasma-processed is kept, wherein the ionization of the gas creates a plasma environment for plasma processing the substrate;
- a transducer assembly to:
- track one or more harmonics that are produced due to nonlinearity of an impedance in a plasma environment, wherein the one or more harmonics are associated with at least one of:
- voltage and/or current;
- one or more spectrum analyzers to:
- analyze the tracked one or more harmonics of the voltage and/or current and apply first derivative tests, level over time tests or peak amplitude tests to follow the process through multiple steps or film layers and arrive at an expected desired endpoint location where endpoint should be found;
- detect an endpoint of the plasma processing based on the analysis of the tracked one or more harmonics wherein a portion of the process identifies, impedance endpoint signatures have a similar shape depicting a region of transition to a region of flatness for identifying first derivative tests;
- and
- a controller to stop the plasma processing based on the detected endpoint.
A plasma processing control system for detecting endpoint utilizing a remote downstream plasma in an exhaust line of a process tool comprising:
- an electrode assembly inserted in an exhaust line of a plasma processing chamber to receive its effluent as a feed gas;
- a power generator to generate an energy for ionizing the received feed gas in the electrode assembly, wherein the ionization of the feed gas leads to a formation of a plasma environment to create a small capacitively coupled plasma;
- a dual directional coupler coupled between the electrode assembly and the power generator, such that both forward power to the electrode assembly and reflected power from the electrode assembly are enable sampling at a dual directional coupler outputs;
- and
- one or more spectrum analyzers to:
- analyze both the sampled forward and reflected power from the dual directional coupler, said dual directional coupler providing outputs of a sampled forward power wave and the corresponding reflected power wave serve as the inputs to the endpoint detection algorithm which may be comprised of sequential mathematical tests to establish process location and subsequent first derivative tests to detect flattening from a region of transition;
- to provide nonlinear conductivity phenomena for creating harmonics in the voltage and current creates harmonics in the sampled forward and reflected waves which can be used for frequency dependent analysis leading to endpoint detection;
- detect an endpoint of the plasma processing based on the analysis of the received forward and reflected power;
- and
- a controller to stop the plasma processing based on the detected endpoint.
A plasma processing control method for detecting an endpoint and controlling plasma processing , the plasma processing control method comprising:
- tracking one or more harmonics that are produced due to nonlinearity of an impedance of a plasma environment, wherein the one or more harmonics are associated with at least one of:
- voltage and current;
- analyzing the tracked one or more harmonics;
- detecting an endpoint of plasma processing based on the analysis of the tracked one or more harmonics;
- and
- stopping the plasma processing based on the detected endpoint.
Dependencies are inferred from the claim text.