Processes for monitoring the levels of oxygen and/or nitrogen species in a substantially oxygen and nitrogen-free plasma ashing process
First Claim
1. A process for monitoring oxygen and/or nitrogen species in a substantially oxygen and nitrogen-free plasma ashing process of a substrate, the process comprising:
- forming reactive species by exposing a plasma gas composition to an energy source to form a plasma substantially free from nitrogen species and oxygen species;
monitoring optical emission signals specifically associated with one or more major components of the plasma gas composition; and
correlating perturbations in the monitored optical emission signals affected by the presence of oxygen and/or nitrogen species in the plasma gas composition to a specific amount of the oxygen and/or nitrogen species in the plasma.
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Abstract
Processes for monitoring the levels of oxygen and/or nitrogen in a substantially oxygen and nitrogen-free plasma ashing process generally includes monitoring the plasma using optical emission. An effect produced by the low levels of oxygen and/or nitrogen species present on other species generally abundant in the plasma is monitored and correlated to amounts of oxygen and nitrogen present in the plasma. This so-called “effect detection” process monitors perturbations in the spectra specifically associated with species other than nitrogen and/or oxygen due to the presence of trace amounts of oxygen and/or nitrogen species and is used to quantitatively determine the amount of oxygen and/or nitrogen at a sensitivity on the order of 1 part per million and potentially 1 part per billion.
131 Citations
19 Claims
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1. A process for monitoring oxygen and/or nitrogen species in a substantially oxygen and nitrogen-free plasma ashing process of a substrate, the process comprising:
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forming reactive species by exposing a plasma gas composition to an energy source to form a plasma substantially free from nitrogen species and oxygen species;
monitoring optical emission signals specifically associated with one or more major components of the plasma gas composition; and
correlating perturbations in the monitored optical emission signals affected by the presence of oxygen and/or nitrogen species in the plasma gas composition to a specific amount of the oxygen and/or nitrogen species in the plasma. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A process for monitoring oxygen and/or nitrogen species in a substantially oxygen and nitrogen-free plasma ashing process of a substrate, the process comprising:
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monitoring a ratio of optical emission signals specifically associated with a ratio of major components of the plasma gas composition in the presence of a fixed amount of oxygen and in the absence of the fixed amount of oxygen; and
calculating a ratio of the ratios during the substantially oxygen and nitrogen-free plasma ashing process and correlating an amount of oxygen and nitrogen species in the plasma from the model curve using the ratio of the ratios. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A process for monitoring nitrogen and/or oxygen species at levels less than 100 ppm in substantially oxygen and/or nitrogen free plasmas, the process comprising:
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measuring spectral perturbations produced by the oxygen and/or nitrogen species present at levels less than 100 ppm in the substantially oxygen and/or nitrogen free plasma on other species that define major components of the plasma; and
correlating the spectral perturbation affected by the presence of the oxygen and/or nitrogen species in the plasma gas composition to a specific amount of oxygen and nitrogen in the plasma. - View Dependent Claims (16, 17)
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18. A process for detecting contamination levels of nitrogen and oxygen in a gas mixture comprising helium and hydrogen, the process comprising:
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generating a plasma with the gas mixture;
monitoring optical emission signals specifically associated with hydrogen and helium species in the plasma; and
correlating perturbations in the monitored optical emission signals affected by the presence of oxygen and/or nitrogen species in the plasma gas composition to a specific amount of the oxygen and/or nitrogen species in the plasma. - View Dependent Claims (19)
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Specification