End point detection in time division multiplexed etch processes
AssigneeUnaxis USA Inc.
InventorsDavid Johnson, Russell Westerman
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Abstract
An improved method for determining endpoint of a time division multiplexed process by monitoring an identified region of a spectral emission of the process at a characteristic process frequency. The region is identified based upon the expected emission spectra of materials used during the time division multiplexed process. The characteristic process frequency is determined based upon the duration of the steps in the time division multiplexed process. Changes in the magnitude of the monitored spectra indicate the endpoint of processes in the time division multiplexed process and transitions between layers of materials.
Claims20
A method for establishing endpoint in a plasma etching process, the method comprising the steps of:
- placing a substrate in a vacuum chamber;
- etching a material from the substrate by means of a plasma;
- depositing a passivation layer on the substrate by means of a plasma;
- performing a process loop of repeating the etching step and the deposition step;
- monitoring a variation in a plasma emission intensity at a process imposed frequency;
- discontinuing the process loop step based on said monitoring step;
- and
- removing the substrate from the vacuum chamber.
A method for detecting the transition between different materials in a time division multiplexed process, the method comprising the steps of:
- placing a substrate in a vacuum chamber;
- performing the time division multiplexed process;
- monitoring a variation in a plasma emission intensity at a process imposed frequency;
- discontinuing the time division multiplexed process based on said monitoring step;
- and
- removing the substrate from the vacuum chamber.
Dependencies are inferred from the claim text.