| CPC H01J 37/32972 (2013.01) [G01B 11/06 (2013.01); H01J 37/32743 (2013.01); H01L 21/32136 (2013.01); H01L 22/26 (2013.01); H01J 2237/24578 (2013.01); H01J 2237/334 (2013.01)] | 7 Claims |
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1. A plasma processing method comprising:
arranging a wafer having a layer to be processed on a surface thereof in a processing chamber inside a vacuum container:
forming plasma in the processing chamber and etching a film formed in advance on a surface of the wafer;
receiving interference light reflected on the surface of the wafer at a plurality of time instants from when the plasma is formed to when the etching is completed;
determining an etching start time instant of the wafer based on data indicating amounts of change per a time period between two of the plurality of time instants in signals, the signals indicating an intensity of the interference light corresponding to each of the plurality of time instants after the plasma is formed and the layer to be processed is exposed to the plasma;
detecting a film thickness or determining reaching an end point of the processing of the wafer using a signal indicating the intensity of the interference light obtained at the plurality of time instants after the determined etching start time; and
controlling the etching of the wafer in accordance with the determined etching start time and the detected film thickness or the determined end point of the processing,
wherein the signal indicating the intensity of the interference light includes a spectral waveform, and the etching start time instant is determined by calculating differences between the spectral waveforms at the two of the plurality time instants, and a time instant when a sum of the differences per the time period between the two of the plurality time instants becomes equal to or more than a predetermined threshold value is determined as the etching start time instant.
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5. A plasma processing apparatus that arranges a wafer having a layer to be processed on a surface thereof in a processing chamber inside a vacuum container, forms plasma in the processing chamber, and etches a film formed in advance on a surface of the wafer, the plasma processing apparatus comprising:
a detector configured to receive interference light reflected on the surface of the wafer and generate a signal indicating intensity of the interference light at a plurality of time instants from when the plasma is formed to when the etching is completed; and
a determiner configured to determine an etching start time instant based on data indicating amounts of change per a time period between two of the plurality of time instants in signals, the signals indicating the intensities of the interference light corresponding to each of the plurality of time instants after the plasma is formed and the layer to be processed is exposed to the plasma, and to detect a film thickness or determine reaching an end point of the processing of the wafer using the signal indicating the intensity of the interference light obtained at the plurality of time instants after the determined etching start time,
wherein the signal indicating the intensity of the interference light includes a spectral waveform, and the determiner is configured to calculate differences between the spectral waveforms at the two of the plurality time instants, and determine as the etching start time instant a time instant when a sum of the differences per the time period between the two of the plurality time instants becomes equal to or more than a predetermined threshold value.
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