Plasma processing apparatus

• US 20070202613A1
• Filed: 03/10/2006
• Published: 08/30/2007
• Est. Priority Date: 02/27/2006
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Fujii, Takashi, Usui, Tatehito, Joo, Kazuhiro
• Granted Patent: US 8,088,247 B2
• Time in Patent Office: Days
• US Class Current: 438/14
• CPC Class Codes: G01B 11/0625 with measurement of absorption or reflection
• 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

A plasma processing apparatus is provided using a method of measuring the thickness of a processed material, by which the actual remaining thickness or etching depth of a processed layer can be correctly measured online. The plasma processing apparatus includes a detector 11 for detecting interference light of multiple wavelengths from a surface of a sample during processing, pattern comparing means 15 for comparing actual deviation pattern data on the interference light obtained at a given time during processing and a plurality of standard deviation patterns corresponding to two or more thicknesses of the film, and calculating a deviation, the standard deviation patterns corresponding to interference light data of multiple wavelengths obtained, before the processing of the sample, for processing of another sample, deviation comparing means 115 for comparing the deviation between the data and a predetermined deviation and outputting data on a thickness of the film of the sample at that time, remaining-thickness time-series data recording means 18 for recording, as time series data, the data on the thickness of the film, and an endpoint decision unit 230 for deciding completion of a predetermined amount of etching by using the data on the thickness of the film.

Claims

1. A plasma processing apparatus for etching a film on a surface of a sample in a vacuum chamber by using plasma formed in the vacuum chamber, comprising:

a detector for detecting interference light of multiple wavelengths from the surface of the sample during processing,

a differentiator for differentiating a change in intensity of the detected interference light to obtain an actual differential pattern of time series actual differential waveforms,

a differential waveform pattern database including a plurality of standard differential waveform patterns corresponding to two or more thicknesses of the film, the standard differential waveform pattern being obtained, before the processing of the sample, by differentiating a change in intensity of the interference light of multiple wavelengths for processing of another sample,

a differential waveform comparator for comparing an actual time differential waveform obtained at a given time by differentiating a change in intensity of the interference light at the given time from start of the processing of the sample and the standard differential waveform pattern stored in the differential waveform pattern database, and outputting a pattern matching deviation of the waveforms,

a deviation setting unit for setting a minimum value of the pattern matching deviation, and

a decision unit for deciding that the thickness of the film reaches a thickness corresponding to a pattern of the data having the minimum pattern matching deviation,

wherein the decision unit decides, when the minimum pattern matching deviation is larger than the predetermined value, that the thickness of the film reaches a thickness estimated from a value of a thickness decided before the given time.

2. The plasma processing apparatus according to claim 1, wherein the decision unit decides, when a minimum value of the deviation is larger than a predetermined value, that the thickness of the film reaches a thickness estimated from a value of a thickness decided before the given time.

3. The plasma processing apparatus according to claim 1, wherein the decision unit decides, when a minimum value of the deviation is larger than a predetermined value, that the thickness of the film reaches a thickness estimated from a value of a thickness decided before the given time, and decides that a thickness of the film at the given time is a value obtained by interpolation using a thickness of the film at each time within a predetermined time before the given time.

4. The plasma processing apparatus according to claim 1, wherein the decision unit decides, when a minimum value of the deviation is larger than a predetermined value, that the thickness of the film reaches a thickness estimated from a value of a thickness decided before the given time, and a thickness of the film at the given time and later is decided using a value obtained by interpolation using a thickness of the film at each time within a predetermined time period before the given time.

5. The plasma processing apparatus according to claim 1, wherein the decision unit decides, when a minimum value of the deviation is larger than a predetermined value, that the thickness of the film reaches a thickness estimated from a value of a thickness decided before the given time, and decides that a thickness of the film at the given time is a value interpolated by extrapolation using a thickness of the film at each time within a predetermined time before the given time.

7. The plasma processing apparatus according to claim 5, wherein the decision unit decides that the thickness of the film at the given time is a value obtained by interpolation using a value of a thickness of the film at each time within a predetermined time period before the given time.

9. The plasma processing apparatus according to any one of claims 5 to 7, wherein the decision unit uses a value interpolated by extrapolation.

6. A plasma processing apparatus for etching a film on a surface of a sample in a vacuum chamber by using plasma formed in the vacuum chamber, comprising:

a detector for detecting interference light of multiple wavelengths from the surface of the sample during processing,

a differentiator for differentiating a change in intensity of the detected interference light to obtain an actual differential pattern of time series actual differential waveforms,

a differential waveform pattern database including a plurality of standard differential waveform patterns corresponding to two or more thicknesses of the film, the standard differential waveform pattern being obtained, before the processing of the sample, by differentiating a change in intensity of the interference light of multiple wavelengths for processing of another sample,

a differential waveform comparator for comparing an actual time differential waveform obtained at a given time by differentiating a change in intensity of the interference light at the given time from start of the processing of the sample and the standard differential waveform pattern stored in the differential waveform pattern database, and outputting a pattern matching deviation of the waveforms,

a deviation setting unit for setting a minimum value of the pattern matching deviation, and

a decision unit for deciding that the thickness of the film reaches a thickness corresponding to a pattern of the data having the minimum pattern matching deviation,

wherein the decision unit decides, when a difference between a value of the decided thickness and a value of a thickness decided at a time immediately before the given time is larger than a predetermined value, that the thickness of the film reaches a thickness estimated from a value of a thickness decided before the given time.

8. The plasma processing apparatus according to claim 6, wherein the decision unit uses a value obtained by interpolation to decide a thickness of the film at the given time and later.

10. A plasma processing apparatus for etching a film on a surface of a sample in a vacuum chamber by using plasma formed in the vacuum chamber, comprising:

a detector for detecting interference light from the surface of the sample in the vacuum chamber, and

a decision unit for comparing interference light data obtained by differentiating output from the detector at a given time during processing with a plurality of data patterns corresponding to two or more thicknesses of the film, and deciding that a thickness of the film reaches a thickness corresponding to the data pattern having a minimum difference from the interference light data, the plurality of data patterns corresponding to the interference light data of multiple wavelengths obtained, before the processing of the sample, by differentiating the output from the detector in processing of another sample,

wherein when a ratio (difference) between an output value of the detector at the given time and output of the detector at a previous time is larger than a predetermined value, the output value at the given time is corrected so as to equalize the ratio (eliminate the difference).

11. A plasma processing apparatus for etching a film on a surface of a sample in a vacuum chamber by using plasma formed in the vacuum chamber, comprising:

a first detector for detecting plasma radiation in the vacuum chamber,

a second detector for detecting interference light from the surface of the sample in the vacuum chamber, and

a decision unit for comparing interference light data obtained by differentiating output from the second detector at a given time during processing with a plurality of data patterns corresponding to two or more thicknesses of the film, and deciding that a thickness of the film reaches a thickness corresponding to the data pattern having a minimum difference from the interference light data, the plurality of data patterns corresponding to the interference light data of multiple wavelengths obtained, before the processing of the sample, by differentiating the output from the second detector in processing of another sample,

wherein when a ratio (difference) of an output value of the first detector at the given time and an output value of the first detector at a previous time is larger than a predetermined value, the output of the second detector is multiplied by a coefficient for equalizing the ratio (eliminating the difference).