Thin film thickness measuring method and apparatus, and method and apparatus for manufacturing a thin film device using the same

• US 6,753,972 B1
• Filed: 08/18/2000
• Issued: 06/22/2004
• Est. Priority Date: 04/21/1998
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ninomiya, Takanori, Tsuchiyama, Hirofumi, Maeda, Shunji, Noguchi, Minori, Hirose, Takenori, Kenbo, Yukio
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): Dinh, Jack
• Application Number:
  US09/622,570
• Time in Patent Office: 1,404 Days
• Field of Search: 356/503, 356/504, 356/630, 356/632
• US Class Current: 356/630
• CPC Class Codes: G01B 11/0625 with measurement of absorption or reflection

Abstract

This invention aims to measure film thickness and film thickness distribution to high precision in a wide range of transparent films. As one example, in a CMP process, the film thickness of an outermost surface layer formed on a step pattern of an actual product can be measured so that high precision film thickness control can be performed. To achieve an increase of processing throughput, the film thickness of an optically transparent film formed on an actual device pattern is controlled to high precision by incorporating a film thickness measuring unit, which performs frequency analysis of a spectral distribution, in a polishing apparatus. As a result, an increase of processing throughput is realized. To perform the high precision measurement, the frequency analysis is performed on the spectral distribution waveform of interference light from white light due to the film, and an absolute value of film thickness is computed from the relation of the phase of frequency components in the waveform and film thickness.

Claims

1. A film thickness measuring method for thin films, characterized in that a sample, wherein an optically transparent thin film is formed on a step pattern, is irradiated by light, the reflected light generated by said sample due to said light irradiation is detected, and the film thickness of the optically transparent thin film formed on said step pattern is calculated based on a frequency and a phase of a spectral distribution waveform of the detected reflected light.

2. A film thickness measuring method for thin films, characterized in that a sample, wherein an optically transparent thin film is formed on a step pattern, is irradiated by light, the reflected light generated by said sample due to said light irradiation is detected, and the film thickness of the optically transparent thin film formed on said step pattern is found by fitting a spectral distribution waveform derived from a structural model of the optically transparent thin film and said step pattern to a spectral distribution waveform of the detected reflected light.

3. A film thickness measuring method as claimed in claim 2, wherein the light which irradiates said sample is white light.

4. A film thickness measuring method for thin films, characterized in that a sample, wherein an optically transparent thin film is formed on a step pattern, is irradiated by white light, the reflected light generated by said sample due to said white light irradiation is detected, and the film thickness of the optically transparent thin film formed on said step pattern is calculated to a precision of at least ±

20 nm by using information of the spectral distribution waveform of the detected reflected light.

5. An apparatus for measuring a film thickness of optically transparent thin films in a sample wherein an optically transparent thin film is formed on a step pattern, said apparatus comprising:

irradiating means for irradiating said sample by light;

detecting means for detecting reflected light generated by said sample irradiated by said irradiating means; and

computing means for computing the film thickness of the optically transparent thin film formed on said step pattern based on a frequency and a phase of a spectral distribution waveform of the reflected light detected by said detecting means.

7. An apparatus as claimed in claim 5 or 6, wherein said irradiating means irradiates said sample with white light.

6. An apparatus for measuring a film thickness of optically transparent thin films in a sample wherein an optically transparent thin film is formed on a step pattern, said apparatus comprising:

irradiating means for irradiating said sample by light;

detecting means for detecting reflected light generated by said sample irradiated by said irradiating means; and

computing means for computing the film thickness of the optically transparent film formed on said step pattern by fitting a spectral distribution waveform derived from a structural model of the optically transparent thin film and said step pattern to a spectral distribution waveform of the detected reflected light.

8. An apparatus for measuring a film thickness of optically transparent thin films in a sample wherein an optically transparent thin film is formed on a step pattern, said apparatus comprising:

irradiating means for irradiating said sample by white light;

detecting means for detecting reflected light generated by said sample irradiated by said irradiating means; and

computing means for computing the film thickness of the optically transparent thin film formed on said step pattern by using information of spectral distribution waveform of the reflected light detected by said detecting means to a precision of at least ±

20 nm.

9. A method of manufacturing a thin film device, characterized in that, in a step for polishing an optically transparent thin film formed on a step pattern of the thin film device, said optically transparent thin film is irradiated by light, the reflected light generated by said sample due to said light irradiation is detected, the film thickness of the optically transparent film thin formed on said step pattern is calculated based on a frequency and a phase of a spectral distribution waveform of the detected reflected light, and polishing is performed based on said calculated result.

10. A method of manufacturing a thin film device, characterized in that, in a step for polishing an optically transparent thin film formed on a step pattern of the thin film device, said optically transparent thin film is irradiated by light, the reflected light generated by said sample due to said light irradiation is detected, the film thickness of the optically transparent thin film formed on said step pattern is found by fitting a spectral distribution waveform derived from a structural model of the optically transparent thin film and said step pattern to a spectral distribution waveform of the detected reflected light, and polishing is performed based on said calculated result.

11. A method claimed in claim 9 or 10, wherein said irradiation by light and detection of said reflected light are performed while polishing said optically transparent thin film.

12. A method as claimed in claim 9 or 10, wherein said irradiation by light and detection of said reflected light are performed after polishing said optically transparent thin film.

13. A method as claimed in claim 9 or 10, wherein the light which irradiates said optically transparent thin film is white light.

14. A method of manufacturing a thin film device, characterized in that an optically transparent film, formed on a step pattern of the thin film device during the manufacture of the thin film device, is irradiated by light, the reflected light generated by said sample due to said light irradiation is detected, and the film thickness of the optically transparent film formed on said step pattern is calculated based on a frequency and a phase of a spectral distribution waveform of the detected reflected light.

15. A method of manufacturing a thin film device, characterized in that an optically transparent film, formed on a step pattern of the thin film device during the manufacture of the thin film device, is irradiated by light, the reflected light generated by said sample due to said light irradiation is detected, and the film thickness of the optically transparent film formed on said step pattern is found by fitting a spectral distribution waveform derived from a structural model of the optically transparent film and said step pattern to a spectral distribution waveform of the detected reflected light.

16. A method of manufacturing a thin film device, characterized in that an optically transparent film is irradiated by white light during a step for polishing the optically transparent film formed on a step pattern of the thin film device, the reflected light generated by said sample due to said light irradiation is detected, the film thickness of the optically transparent film formed on said step pattern is calculated by using information of a spectral distribution waveform of the detected reflected light to a precision of at least ±

20 nm, and said polishing step is controlled based on the calculated result.

17. An apparatus for manufacturing a thin film device, comprising:

polishing means for polishing an optically transparent film formed on a step pattern of said thin film device;

irradiating means for irradiating said sample by light;

detecting means for detecting reflected light generated by said sample irradiated by said irradiating means; and

film thickness computing means for computing the film thickness of the optically transparent film formed on said step pattern based on a frequency and a phase of a spectral distribution waveform of the reflected light detected by said detecting means.

21. An apparatus as claimed in any of claims 17 to 20, wherein said irradiating means irradiates white light.

18. An apparatus for manufacturing a thin film device, comprising:

polishing means for polishing an optically transparent film formed on a step pattern of said thin film device;

irradiating means for irradiating said sample by light, detecting means for detecting reflected light generated by said sample irradiated by said irradiating means; and

film thickness computing means for computing the film thickness of the optically transparent film formed on said step pattern by fitting a wavelength dependent waveform derived from a structural model of the optically transparent film and said step pattern to a wavelength dependent spectral distribution waveform of the detected reflected light.

19. An apparatus for manufacturing a thin film device, comprising:

irradiating means for irradiating an optically transparent film formed on a step pattern of said thin film device by light;

detecting means for detecting reflected light generated by said sample irradiated by said irradiating means; and

computing means for computing the film thickness of the optically transparent film formed on said step pattern based on a freqency and a phase of a spectral distribution waveform of the reflected light detected by said detecting means.

20. An apparatus for manufacturing a thin film device, comprising:

irradiating means for irradiating an optically transparent film formed on a step pattern of said thin film device by light;

detecting means for detecting reflected light generated by said sample irradiated by said irradiating means; and

computing means for computing the film thickness of the optically transparent film formed on said step pattern by fitting a spectral distribution waveform derived from a structural model of the optically transparent film and said step pattern to a wavelength dependent spectral distribution waveform of the detected reflected light.

22. An apparatus for manufacturing a thin film device, comprising:

polishing means for polishing an optically transparent film formed on a step pattern of said thin film device;

irradiating means for irradiating said sample by white light;

detecting means for detecting reflected light generated by said sample irradiated by said irradiating means; and

film thickness computing means for computing the film thickness of the optically transparent film formed on said step pattern by using information of a phase of a spectral distribution waveform of the reflected light detected by said detecting means to a precision ±

20 nm.