Methods and apparatuses for effectively reducing gas residence time in a plasma processing chamber

摘要

Methods and apparatuses for controlling plasma generation in a plasma processing chamber to reduce an effective residence time of by-product gases or to control in real time the concentration of certain polymer pre-cursors or reaction by-products in the plasma processing chamber are disclosed. The gas residence time is “effectively” reduced by reducing the plasma reaction for at least a portion of the process time. Thresholds can be provided to control when the plasma reaction is permitted to proceed at the full rate and when the plasma reaction is permitted to proceed at the reduced rate. By reducing the rate of plasma by-product generation at least for a portion of the process time, the by-product gas residence time may be effectively reduced to improve process results.

主权项

1. A plasma processing system having at least one plasma processing chamber for processing a substrate, comprising: a lower electrode for supporting said substrate; a chamber ceiling disposed above said lower electrode such that a plasma processing region exists between an upper surface of said substrate and said chamber ceiling during said processing; a plasma generation power source for providing energy to generate a plasma in said plasma processing region from supplied reactant gas; a light emitting apparatus for emitting a first light into said plasma processing region; a light receiving apparatus for receiving a second light, said second light representing an altered version of said first light after said first light passes through said plasma processing region; and
a controller configured to analyze said second light to ascertain whether a parameter of said second light equals or exceeds a first threshold indicative of a first concentration of by-product gases resulting from a reaction of the plasma with an exposed surface of the substrate or equals or falls below a second threshold indicative of a second concentration of the by-product gases, wherein said controller controls an effective gas residence time of by-product gases on the upper surface of the substrate by adjusting the plasma generation energy level between a full mode of plasma generation and a reduced mode of plasma generation by sending a first signal for reducing an amount of plasma generation energy to a plasma generation energy level associated with the reduced mode of plasma generation provided by said plasma generation power source if said parameter of said second light equals or exceeds said first threshold, said controller sends a second signal for increasing said amount of plasma generation energy provided by said plasma generation power source to a plasma generation energy level associated with the full mode of plasma generation if said parameter of said second light equals or falls below said second threshold, wherein the plasma generation energy level associated with the reduced mode of plasma generation is sufficiently low as to minimize or stop the reaction of the plasma with exposed surfaces of the substrate such that the concentration of by-product gases reduces over time in the reduced mode of plasma generation, and wherein the plasma generation energy level associated with the full mode of plasma generation is sufficiently high as to increase the reaction of the plasma with exposed surfaces of the substrate to a full level in which the concentration of by-product gases increases over time in the full mode of plasma generation.