Edge detector

• US 5,304,924 A
• Filed: 11/20/1992
• Issued: 04/19/1994
• Est. Priority Date: 03/29/1989
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Oguchi, Takahiro, Kawase, Toshimitsu, Yamano, Akihiko, Miyazaki, Toshihiko, Nose, Hiroyasu
• Primary Examiner(s): NGUYEN, VINH P
• Application Number:
  US07/979,472
• Time in Patent Office: 515 Days
• Field of Search: 324/158 R, 324/158 D, 324/73.1, 324/72.5, 356/72, 356/357, 356/358, 250/306, 250/307, 250/310-311, 250/423 F, 250/442.1, 439/482
• US Class Current: 324/754.26
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01B 11/02 for measuring length, width or thickness G01B11/08 takes precedence
• CPC Class Codes: G01B 21/20 for measuring contours or curvatures, e.g. determining profile
• CPC Class Codes: G01Q 10/06 Circuits or algorithms therefor
• CPC Class Codes: G01Q 30/02 Non-SPM analysing devices, e.g. SEM [Scanning Electron Microscope], spectrometer or optical microscope
• CPC Class Codes: Y10S 977/852 for detection of specific nanostructure sample or nanostructure-related property

Abstract

An edge detector is disclosed, which detector is improved by providing a probe moving relatively with a tested pattern, a device for detecting a working force or a tunnel current generated between the probe and the tested pattern, and a device for detecting an edge of the tested pattern according to the detected working force or tunnel current. An edge of the tested pattern is detected at high resolution by detecting the tunnel current flowing between a conductive tested pattern and a probe kept closely opposite thereto, or by detecting an atomic force or a magnetic force working between an insulated or a magnetic tested pattern and a lever.

Claims

1. An apparatus for detecting at least one interval between a plurality of edge portions present on a tested surface, said apparatus comprising:

a probe for relatively moving along the tested surface;

detection means for detecting one of a working force and a tunnel current generated between said probe and the tested surface and for producing a detection output;

edge detection means comprising means for receiving the detection output signal, and means for detecting edge portions on the tested surface according to one of the working force and the tunnel current detected by said detection means and for producing an edge detection output; and

edge interval detection means comprising means for receiving the edge detection output and means for detecting at least one edge interval between the edge portions detected by said edge detection means, said edge interval detection means being distinct from said edge detection means.

2. The apparatus as defined in claim 1, further comprising probe position control means for controlling position of said probe to keep constant the detection output produced by said detection means and for producing a probe position control output.

3. The apparatus as defined in claim 2, wherein said edge detection means comprises means for detecting edges from a differential signal of the probe position control output produced by said probe.

4. The apparatus as defined in claim 1, further comprising vibration means for vibrating said probe at a predetermined frequency in a predetermined direction, said edge detection means comprising means for detecting edge portions according to a change in amplitude of a predetermined frequency component of the outgoing signal of said detection means when the probe is vibrated by said vibration means.

5. The apparatus as defined in claim 4, further comprising probe position control means for controlling a position of the probe so as to steady a component other than the predetermined frequency component of the outgoing signal of said detection means.

6. The apparatus as defined in claim 4, wherein said vibration means comprises means for vibrating said probe in the direction of the tested surface.

7. The apparatus as defined in claim 4, wherein said vibration means comprises means for vibrating said probe in a direction parallel to the tested surface.

8. The apparatus as defined in claim 1, wherein said detection means comprises means for detecting an atomic force generated between said probe and the tested surface as the working force.

9. The apparatus as defined in claim 1, wherein said detection means comprises means for detecting a magnetic force generated between said probe and the tested surface as a working force.

10. The apparatus as defined in claim 1, wherein said edge interval detection means comprises an interferometer for generating signals at each unit distance related to a wavelength of the light.

11. The apparatus as defined in claim 1, wherein said interval detection means comprises means for detecting the line width of a pattern provided on the tested surface.

12. The apparatus as defined in claim 1, wherein said edge interval detection means comprises a grid interferometer for generating signals at each of predetermined distances according to a pitch of a diffraction grid.

13. The apparatus as defined in claim 1, wherein said edge interval detection means comprises a mirror for moving integrally with the tested surface, and means for detecting a reflected light incident position when a luminous flux is irradiated on the mirror, and means for detecting a distance from the incident position detected by the detection means.

14. The apparatus as defined in claim 1, wherein said edge interval detection means comprises means for detecting a distance according to an electric capacity of a plate moving integrally with the tested surface and a fixed plate.

15. The apparatus as defined in claim 1, wherein said edge interval detection means comprises a reference scale for moving integrally with the tested surface, and a tunnel current detecting probe provided opposite to the scale, and means for detecting a distance according to a tunnel current detected by said tunnel current detecting probe.

16. An apparatus for measuring a line width of a pattern present on a tested surface, said apparatus comprising:

a probe for relatively moving along the tested surface;

movement distance detection means for detecting a relative distance of movement between said probe and the tested surface, and for producing a movement distance detection signal;

detection means for detecting one of a working force and a tunnel current generated between said probe and the tested surface, and for producing a detection signal;

edge detection means for detecting edge portions at both ends of a predetermined pattern on the tested surface according to one of the working force and the tunnel current detected by said detection means, and for producing an edge detection signal; and

pattern line width detection means for detecting a pattern line width according to the edge detection signal, indicative of both end edge portions of the predetermined pattern detected by said edge detection means, and according to the movement distance signal detected by said movement distance detection means, indicative of a distance of movement during the detection of both end edge portions.

17. The apparatus as defined in claim 16, further comprising probe position control means for controlling position of said probe to keep constant the detection output signal produced by said detection means, and for producing a probe position control signal, wherein said edge detection means comprises means for detecting edge portions based on the control signal produced by said probe position control means.

18. The apparatus as defined in claim 16, further comprising vibration means for vibrating said probe at a predetermined frequency in a predetermined direction along the tested surface, wherein said edge detection means comprises means for detecting edge portions on the basis of a change in amplitude of a predetermined frequency component of the detection signal produced by said detection means when said vibration means vibrates said probe.

19. The apparatus as defined in claim 16, wherein said detection means comprises means for detecting an atomic force generated between said probe and the tested surface as the working force.

20. The apparatus as defined in claim 16, wherein said detection means comprises means for detecting a magnetic force generated between said probe and the tested surface as the working force.

21. An apparatus for measuring an interval between a plurality of edge portions present on a tested surface, said apparatus comprising:

a probe positioned opposite to the tested surface;

detection means for detecting one of a working force and a tunnel current generated between said probe and the tested surface and for producing a detection output;

edge detection means for receiving the detection output, for detecting the edge portions according to one of the working force and the tunnel current detected by said detection means and for producing an edge detection output;

movement means for relatively moving said probe along the tested surface from one of the edge portions to another;

movement distance detection means for detecting a relative distance of movement between said probe and the tested surface, and for producing a movement distance detection signal; and

measurement means for receiving the edge detection output and the movement distance detection signal, and for measuring a distance of relative movement of the probe moved by said movement means from a position where said edge detection means detects the one edge portion to a position where said edge detection means detects the other edge portion.

22. An apparatus as defined in claim 21, further comprising:

probe position control means for controlling the position of said probe to keep constant the detection output produced by said detection means, and for producing a probe position control signal.

23. An apparatus as defined in claim 22, wherein said edge detection means detects the edge portions from a differential signal of said control signal.

24. An apparatus as defined in claim 21, further comprising vibration means for vibrating said probe at a predetermined frequency in a predetermined direction,

wherein said edge detection means detects the edge portions according to a change in amplitude of a predetermined frequency component of a monitoring signal of one of the working force and the tunnel current generated between said probe and the tested surface when the probe is vibrated by said vibration means.

25. An apparatus as defined in claim 24, further comprising a filter for eliminating the predetermined frequency component from the monitoring signal and for producing a filtered signal, and probe position control means for receiving the filtered signal and for controlling the position of said probe to keep the filtered signal constant.

26. An apparatus as defined in claim 24, wherein said vibration means vibrates said probe in a direction perpendicular to the tested surface.

27. An apparatus as defined in claim 24, wherein said vibration means vibrates said probe in a direction parallel to the tested surface.

28. An apparatus as defined in claim 21, wherein said edge detection means monitors an atomic force generated between said probe and the tested surface as the working force.

29. An apparatus as defined in claim 21, wherein said edge detection means monitors a magnetic force generated between said probe and the tested surface as the working force.

30. An apparatus as defined in claim 21, wherein said edge detection means comprises voltage application means for applying a voltage between said probe and the tested surface, and tunnel current detection means for detecting a tunnel current flowing between said probe and the tested surface when applying the voltage.

31. An apparatus as defined in claim 21, wherein said movement distance detection means comprises an interferometer for generating signals at each of predetermined unit distances relative to light wavelength.

32. An apparatus as defined in claim 21, wherein said movement distance detection means comprises a grid interferometer for generating signals at each of predetermined distances according to a pitch of a diffraction grid.

33. An apparatus as defined in claim 21, wherein said movement distance detection means comprises a mirror moving together with the tested surface, means for causing light flux to be incident on said mirror at a non-perpendicular angle, and means for measuring the distance of movement by a shift of a receiving position at which light reflected on said mirror is received, of reflected light caused by moving the mirror.

34. An apparatus as defined in claim 21, wherein said movement distance detection means comprises a first pole plate that moves together with the tested surface, a second pole plate that is fixed, and means for measuring the distance of movement by a change in electric capacity between the first pole plate and the second pole plate caused by moving the first pole plate.

35. An apparatus as defined in claim 21, wherein said movement distance detection means comprises a reference scale moving together with the tested surface, a second probe provided opposite to said reference scale, means for applying a voltage between the reference scale and the second probe, means detecting a tunnel current flowing between the reference scale and the second probe by applying the voltage, and means for measuring the distance of movement by a change in tunnel current caused by moving the reference scale.

36. An apparatus as defined in claim 21, wherein said edge detection means comprises line width detection means for detecting a line width of a pattern provided on the tested surface.

37. A method of measuring an interval between a plurality of edge portions present on a tested surface by using an apparatus comprising:

a probe positioned opposite to the tested surface;

detection means for detecting one of a working force and a tunnel current generated between the probe and the tested surface and for producing a detection output;

edge detection means for receiving the detection output, for detecting the edge portions according to one of the working force and the tunnel current detected by said detection means and for producing an edge detection output;

movement means for relatively moving said probe along the tested surface from one of the edge portions to another;

movement distance detection means for detecting a relative distance of movement between said probe and the tested surface, and for producing a movement distance detection signal, said method comprising the steps of;

detecting one of the edge portions by the edge detection means;

relatively moving the probe from the one edge portion to the other by the movement means;

detecting the other edge portion by the edge detection means;

detecting a relative distance of movement between the probe and the tested surface by the movement distance detection means;

producing a movement distance detection signal by the movement distance detection means; and

measuring a relative distance of movement of the probe moved by said movement means from a position where the edge detection means detects the one edge portion to a position where said edge detection means detects the other edge portion in accordance with the edge detection output produced by the edge detection means and the movement distance detection signal produced by the movement distance detection means.

38. A method as defined in claim 37, further comprising the steps of:

controlling the position of the probe to keep constant the detection output produced by the detection means; and

producing a probe position control signal.

39. A method as defined in claim 38, further comprising detecting the edge portions by the edge detection means from a differential signal of the control signal.

40. A method as defined in claim 37, further comprising vibrating the probe at a predetermined frequency in a predetermined direction, and detecting the edge portions by the edge detection means according to a change in amplitude of a predetermined frequency component of a monitoring signal of one of the working force and the tunnel current generated between the probe and the tested surface when the probe is vibrated.

41. A method as defined in claim 40, further comprising the steps of:

filtering the monitoring signal to eliminate the predetermined frequency component and to produce a filtered signal; and

controlling a position of the probe to keep the filtered signal constant.

42. A method as defined in claim 40, further comprising vibrating the probe in a direction perpendicular to the tested surface.

43. A method as defined in claim 40, further comprising vibrating the probe in a direction parallel to the tested surface.

44. A method as defined in claim 37, further comprising monitoring by the edge detection means an atomic force generated between the probe and the tested surface as the working force.

45. A method as defined in claim 37, further comprising monitoring by the edge detection means a magnetic force generated between the probe and the tested surface as the working force.

46. A method as defined in claim 37, further comprising applying by the edge detection means a voltage between the probe and the tested surface and detecting a tunnel current flowing between the probe and the tested surface by applying the voltage.

47. A method as defined in claim 37, further comprising measuring the distance of movement of the probe by an interferometer that generates signals at each of predetermined unit distance relative to light wavelength.

48. A method as defined in claim 37, further comprising measuring the distance of movement of the probe by a grid interferometer that generates signals at each of predetermined distances according to a pitch of a diffraction grid.

49. A method as defined in claim 37, further comprising moving a mirror together with the tested surface, causing light flux to be incident on the mirror at a nonperpendicular angle and receiving the light reflected on the mirror to monitor a shift of a receiving position of the reflected light caused by moving the mirror, to measure the distance of movement of the probe.

50. A method as defined in claim 37, further comprising moving a first pole plate together with the tested surface and fixing a second pole plate, and monitoring a change in electric capacity between the first pole plate and the second pole plate caused by moving the first pole plate, to measure the distance of movement of the probe.

51. A method as defined in claim 37, further comprising moving a reference scale together with the tested surface, providing a second probe provided opposite to the reference scale to apply a voltage between the reference scale and the second probe and detecting a tunnel current flowing between the reference scale and the second probe by applying the voltage to monitor a change in tunnel current according to movement of the reference scale, to measure the distance of movement of the probe.