PLASMA PROCESSING APPARATUS

• US 20080216956A1
• Filed: 09/06/2007
• Published: 09/11/2008
• Est. Priority Date: 03/07/2007
• Status: Abandoned Application

• Current Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Usui, Tatehito, Uchida, Hiroshige, Fujii, Takashi, NAKAMOTO, SHIGERU, Joo, Kazuhiro
• Application Number:
  US11/850,722
• Publication Number:
  US 20080216956A1
• Time in Patent Office: Days
• US Class Current: 156/345.25
• CPC Class Codes: G01B 11/0625 with measurement of absorption or reflection
• CPC Class Codes: G01B 11/0683 measurement during deposition or removal of the layer
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32972 Spectral analysis

Abstract

To provide a plasma processing apparatus using a measuring method of a film thickness of a material to be processed, which method is capable of accurately measuring an actual residual film amount and an etching depth of the layer to be processed. The plasma processing apparatus includes: a detector 11 adapted to detect interference light of a plurality of wavelengths from the surface of a sample in a vacuum container; pattern comparing means 15 adapted to compare actual deviation pattern data relating to the interference light obtained at an arbitrary time point during the processing of the sample, with a plurality of standard deviation patterns which are data of interference light of a plurality of wavelengths relating to processing of another sample obtained before the processing of the sample, and which correspond to a plurality of thicknesses of the film, and adapted to calculate a deviation between the actual deviation pattern data and the standard deviation patterns; deviation comparing means 115 adapted to compare the deviation between the actual deviation pattern data and the standard deviation patterns, with a deviation set beforehand, and to output data relating to the film thickness of the sample at the time; residual film thickness time series data recording means 18 adapted to record the data relating to the film thickness as time series data; and an end point determining device 230 adapted to determine that etching of a predetermined amount is ended, by using the data of the film thickness.

Claims

1. A plasma processing apparatus adapted to perform etching processing of a film on the surface of a sample in a vacuum container by using plasma formed in the vacuum container, comprising:

a detector adapted to detect interference light of a plurality of wavelengths from the sample surface during the processing;

pattern comparing means adapted to compare actual deviation pattern data relating to the interference light obtained at an arbitrary time point during the processing of the sample, with a plurality of standard deviation patterns which are data of interference light of the plurality of wavelengths, relating to processing of another sample obtained before the processing of the sample, and which correspond to a plurality of thicknesses of the film, and adapted to calculate a deviation between the actual deviation pattern data and the plurality of standard deviation patterns;

deviation comparing means adapted to compare the deviation between the actual deviation pattern data and the plurality of standard deviation patterns with a deviation set beforehand, and to output data relating to a film thickness of the sample at the arbitrary time point;

residual film thickness time series data recording means adapted to record the data relating to the film thickness from the deviation comparison means as time series data; and

an end point determining device adapted to determine that an etching of a predetermined amount is ended, by using the data on the film thickness from the deviation comparison means.

2. The plasma processing apparatus according to claim 1, wherein when a minimum value of the deviation is larger than a predetermined value, the determining device determines the reaching of the film thickness estimated from the value of the film thickness determined before the arbitrary time point.

3. The plasma processing apparatus according to claim 1,

wherein the determining device is means adapted, when a minimum value of the deviation is larger than a predetermined value, to determine the reaching of the film thickness estimated from the value of the film thickness determined before the arbitrary time point, and to determine a value obtained by interpolation using film thickness values at each time point within a predetermined time period before the arbitrary time point, as a film thickness at the arbitrary time point.

4. The plasma processing apparatus according to claim 1,

wherein the determining device is means adapted, when a minimum value of the deviation is larger than a predetermined value, to determine the reaching of the film thickness estimated from the value of the film thickness determined before the arbitrary time point, and to use a value obtained by performing interpolation using film thickness values at respective time points within a predetermined time period before the arbitrary time point, for determining the film thickness at a time point after the arbitrary time point.

5. The plasma processing apparatus according to claim 1,

wherein the determining device is means adapted, when a minimum value of the deviation is larger than a predetermined value, to determine the reaching of the film thickness estimated from the value of the film thickness determined before the arbitrary time point, and to determine a value obtained by performing extrapolation using film thickness values at respective time points within a predetermined time period before the arbitrary time point, as the film thickness at a time point after the arbitrary time point.

6. A plasma processing apparatus adapted to perform etching processing of a film on the surface of a sample in a vacuum container by using plasma formed in the vacuum container, comprising:

a detector adapted to detect interference light of a plurality of wavelengths from the sample surface during the processing;

a differentiator adapted to obtain an actual differential pattern constituted by a time series of actual differential waveforms by differentiating changes in intensity of the detected interference light;

a differential waveform pattern database which is a differential waveform obtained by differentiating a change in intensity of interference light of the plurality of wavelengths relating to processing of another sample obtained before the processing of the sample, and which is constituted by a plurality of standard differential waveforms respectively corresponding to a plurality of thicknesses of the film;

a differential waveform comparator adapted to compare a real time differential waveform formed by differentiating a change in intensity of interference light obtained at an arbitrary time point from the start of the processing of the sample, with a pattern of standard differential waveforms stored in the differential waveform pattern database, and to output a pattern matching deviation value between the real time differential waveform and the pattern of standard differential waveforms;

a deviation value setting device in which a minimum value of the pattern matching deviation value is set; and

a determining device adapted to determine reaching of a film thickness corresponding to a pattern of the data for which the pattern matching deviation value is minimized,

wherein when a difference between the determined film thickness value and a film thickness value determined at a time point just before the arbitrary time point is larger than a predetermined value, the determining device determines reaching of a film thickness estimated from the film thickness determined before the arbitrary time point.

7. The plasma processing apparatus according to claim 6, comprising the determining device which determines a value obtained by performing interpolation using film thickness values at respective time points within a predetermined time period before the arbitrary time point, as a film thickness at the arbitrary time point.

8. The plasma processing apparatus according to claim 6, further comprising

the value obtained by performing interpolation as the determination value used for the film thickness determination at the arbitrary time point and at a time point subsequent to the arbitrary time point.

9. The plasma processing apparatus according to claim 6 or claim 7, further comprising

a determining device adapted to use a value obtained by performing extrapolation.

10. A plasma processing apparatus adapted to perform etching processing of a film on the surface of a sample in a vacuum container by using plasma formed in the vacuum container, comprising:

a detector adapted to detect interference light from the sample surface in the vacuum container; and

a determining device adapted to compare data relating to the interference light obtained by differentiating an output obtained from the detector at an arbitrary time point during the processing, with a plurality of patterns of data which are interference light data of a plurality of wavelengths obtained by differentiating the outputs from the detector in processing of another sample obtained before the processing of the sample, and which respectively correspond to a plurality of thicknesses of the film, and to determine reaching of a film thickness at which the difference between the data and the plurality of patterns is minimized,

wherein when a ratio (difference) between the output value of the detector at the arbitrary time point and an output value of the detector at a time point just before the arbitrary time point is larger than a predetermined value, the output value at the arbitrary time point is corrected to make the ratio at the arbitrary time point equal to the ratio at the time point just before the arbitrary time point (to eliminate the difference therebetween).

11. A plasma processing apparatus adapted to perform etching processing of a film on the surface of a sample in a vacuum container by using plasma formed in the vacuum container, comprising:

a first detector adapted to detect light emission of plasma in the vacuum container;

a second detector adapted to detect interference light from the sample surface in the vacuum container; and

a determining device adapted to compare data relating to the interference light obtained by differentiating an output obtained from the second detector at an arbitrary time point during the processing, with a plurality of patterns of data which are interference light data of a plurality of wavelengths obtained by differentiating outputs obtained from the second detector in processing of another sample obtained before the processing of the sample, and which respectively correspond to a plurality of thicknesses of the film, and to determine reaching of a film thickness at which the difference between the data and the plurality of patterns is minimized,

wherein when a ratio (difference) between an output value of the first detector at the arbitrary time point and an output value of the first detector at a time point just before the arbitrary time point is larger than a predetermined value, a coefficient obtained to make the output value at the arbitrary time point equal to the output value at the time point just before the arbitrary time point (to eliminate the difference therebetween) is multiplied to the output of the second detector at the arbitrary time point.

12. A plasma processing apparatus adapted to perform etching processing of a film on the surface of a sample in a vacuum container by using plasma formed in the vacuum container, comprising:

a detector adapted to detect interference light of a plurality of wavelengths from the sample surface during the processing;

a differentiator adapted to obtain an actual differential pattern constituted by a time series of actual differential waveforms obtained by differentiating changes in intensity of the detected interference light;

a differential waveform pattern database which is a differential waveform obtained by differentiating a change in intensity of interference light of the plurality of wavelengths relating to processing of another sample obtained before the processing of the sample, and which is constituted by a plurality of standard differential waveforms respectively corresponding to a plurality of thicknesses of the film;

a differential waveform comparator adapted to compare a real time differential waveform at an arbitrary time point formed by differentiating a change in intensity of the interference light obtained at the arbitrary time point from the start of the processing of the sample, with a pattern of a standard differential waveform stored in the differential waveform pattern database, and to output a pattern matching deviation value between the real time differential waveform and the pattern of the standard differential waveform;

an etching rate comparator adapted to compare a current etching rate calculated on the basis of an instantaneous film thickness value obtained by the differential waveform comparator, with an etching rate of the differential waveform pattern database;

a film thickness corrector adapted, when the current etching rate is abnormal, to correct the current etching rate to the etching rate of the differential waveform pattern database; and

an end point determining device adapted to determine that the etching of a predetermined amount is ended, by using film thickness data from the film thickness corrector.