Process for device fabrication in which the plasma etch is controlled by monitoring optical emission
First Claim
1. A process for device fabrication comprising:
- placing a substrate in a reaction chamber which is adapted for plasma generation, the substrate having a layer of silicon dioxide on at least a portion of one surface thereof, and a photoresist mask over the silicon dioxide layer wherein at least a portion of the silicon dioxide layer is exposed through the mask;
introducing a fluorocarbon-containing gas in the reaction chamber;
generating a plasma in the reaction chamber to remove the silicon dioxide exposed through the mask from the substrate;
monitoring the optical emission of the plasma and measuring the luminous intensity associated with at least one species in the plasma;
calculating a value from the measured luminous intensity;
comparing the calculated value to a range of calibration values, wherein the range of calibration values is associated with either an etch rate of the photoresist mask or an etch rate of the silicon dioxide layer; and
controlling the process based upon the comparison.
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Accused Products
Abstract
The present invention is directed to a process for device fabrication in which a pattern is transferred from a photoresist mask into an underlying layer of silicon dioxide. A plasma containing a fluorocarbon gas is used to etch the pattern into the underlying silicon dioxide layer. The plasma is monitored using optical emission spectroscopy to effect control of the etch process. The optical emission is monitored at select wavelengths. To control the process based on an observation of photoresist etch rate, two wavelengths are monitored. One is associated with a species that is produced by the interaction between the photoresist and the plasma, and one is associated with a species related to the plasma intensity. The ratio of the optical intensity at these two wavelengths is determined in real time during processing, and the ratio is associated with acceptable process conditions by referring to a predetermined calibration curve that associates a particular ratio with a particular photoresist etch rate for a given set of process conditions. If the ratio is observed to not be within a certain range of ratios determined to indicate acceptable process conditions, the plasma conditions are either changed to bring the ratio back within the desired range, or the process is stopped until the problem is corrected. To control the process based on an observation of contact hole etch rate, a wavelength associated with one species in the plasma is monitored at two different times during the etch. A ratio of the measured intensity at these two different times is obtained. Calibration information is then used to determine if the ratio indicates that the process is proceeding acceptably. If the ratio is not within the acceptable range, remedial action is taken.
129 Citations
12 Claims
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1. A process for device fabrication comprising:
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placing a substrate in a reaction chamber which is adapted for plasma generation, the substrate having a layer of silicon dioxide on at least a portion of one surface thereof, and a photoresist mask over the silicon dioxide layer wherein at least a portion of the silicon dioxide layer is exposed through the mask; introducing a fluorocarbon-containing gas in the reaction chamber; generating a plasma in the reaction chamber to remove the silicon dioxide exposed through the mask from the substrate; monitoring the optical emission of the plasma and measuring the luminous intensity associated with at least one species in the plasma; calculating a value from the measured luminous intensity; comparing the calculated value to a range of calibration values, wherein the range of calibration values is associated with either an etch rate of the photoresist mask or an etch rate of the silicon dioxide layer; and controlling the process based upon the comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification