Method and apparatus for detecting end point
View Patent ↗A mask layer and a to-be-processed layer are irradiated with light to measure interference light formed of reflected lights from the mask layer and reflected lights from the to-be-processed layer. Thereafter, an interference component brought by the mask layer is removed from the waveform of the measured interference light, thereby calculating the waveform of the interference light brought by the to-be-processed layer. The thickness of the remaining to-be-processed layer is determined on the basis of the calculated waveform of the interference light and the thickness of the remaining to-be-processed layer is compared with a desired thickness thereof. In this way, an end point of processing on the to-be-processed layer is detected.
1. An apparatus for detecting an end point used in processing a to-be-processed layer using a mask layer formed on the to-be-processed layer, said apparatus comprising;
a light source for irradiating the mask layer and the to-be-processed layer with light;
a spectroscope for measuring interference light formed of reflected lights from the mask layer and reflected lights from the to-be-processed later under the light from the light source;
arithmetic means for removing an interference component brought by the mask later from the interference light measured by the spectroscope to calculate the waveform of the interference light brought by the to-be-produced later; and
end-point detection means for determining the thickness of the remaining to-be-processed layer based on the waveform of the interference light calculated by the arithmetic means and comparing the determined thickness of the remaining to-be-processes layer to a desired thickness thereof, thereby detecting the end point of the processing on the to-be-processed layer,
wherein the arithmetic means determines the ratio of the intensity of the measured interference light for at least one kind of specific wavelength to the sum of the intensities of the measured interference light for at least ten or more kinds of wavelengths to remove the interference component brought by the mask layer from the measured interference light.
2. An apparatus for detecting an end point used in processing a to-be-processed layer using a mask layer formed on the to-be-processed layer, said apparatus comprising;
a light source for irradiating the mask layer and the to-be-processed layer with light;
a spectroscope for measuring interference light formed of reflected lights from the mask layer and reflected lights from the to-be-processed later under the light from the light source;
arithmetic means for removing an interference component brought by the mask later from the interference light measured by the spectroscope to calculate the waveform of the interference light brought by the to-be-produced later; and
end-point detection means for determining the thickness of the remaining to-be-processed layer based on the waveform of the interference light calculated by the arithmetic means and comparing the determined thickness of the remaining to-be-processes layer to a desired thickness thereof, thereby detecting the end point of the processing on the to-be-processed layer,
wherein the arithmetic means determines the ratio of the intensity of the measured interference light for at least one kind of specific wavelength to the integral of the intensity of the measured interference light over a predetermined wavelength range to remove the interference component brought by the mask layer from the measured interference light.
3. An apparatus for detecting an end point used in processing a to-be-processed layer using a mask layer formed on the to-be-processed layer, said apparatus comprising;
a light source for irradiating the mask layer and the to-be-processed layer with light;
a spectroscope for measuring interference light formed of reflected lights from the mask layer and reflected lights from the to-be-processed later under the light from the light source;
arithmetic means for removing an interference component brought by the mask later from the interference light measured by the spectroscope to calculate the waveform of the interference light brought by the to-be-produced later; and
end-point detection means for determining the thickness of the remaining to-be-processed layer based on the waveform of the interference light calculated by the arithmetic means and comparing the determined thickness of the remaining to-be-processes layer to a desired thickness thereof, thereby detecting the end point of the processing on the to-be-processed layer,
wherein the arithmetic means predicts the interference component brought by the mask layer on the basis of the initial thickness of the mask layer, the initial thickness of the to-be-processed layer, the etching rate of the to-be-processed layer, and the etching rate of the mask layer and removes the predicted interference component from the measured interference light.