Position measuring device, position measurement method, exposure apparatus, exposure method, and superposition measuring device and superposition measurement method

• US 7,106,444 B2
• Filed: 06/22/2004
• Issued: 09/12/2006
• Est. Priority Date: 03/24/1999
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Nakajima, Shinichi
• Primary Examiner(s): Toatley, Jr., Gregory J.
• Assistant Examiner(s): Stock, Jr., Gordon J.
• Application Number:
  US10/872,461
• Publication Number:
  US 20040223157A1
• Time in Patent Office: 812 Days
• Field of Search: 356/614, 356399-401, 250/548, 250/492.2, 250/559.01, 250/559.29, 250/559.3, 355/53, 355/55, 430/22, 430/30, 382/151, 700/121, 700/125, 702/94, 702/150
• US Class Current: 356/401
• CPC Class Codes: G03F 9/7088 Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection
• CPC Class Codes: G03F 9/7092 Signal processing

Abstract

This position measuring device comprising a calculation unit 19 calculates mark position information relating to the position of the mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object W, and a correction device 19 for correcting the calculation results from the calculation unit 19 based on the asymmetry of the mark signal.

As a result, positional deviation resulting from asymmetry can be detected, and by correcting for this deviation the effect that the image asymmetry has on the measurement can be reduced. Therefore, a more accurate high precision alignment can be performed, and there is no requirement to increase the NA of the detection optical system, nor to prepare a special short wavelength light source, meaning increases in the size and cost of the apparatus can also be prevented.

Claims

1. A position measuring device comprising a calculation unit which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object,

wherein the calculation unit includes a processing unit which performs predetermined processing on predetermined information to be used when calculating the mark position information, and generates a plurality of processing information, and

the position measuring device further comprises a correction unit which is electrically connected to the calculation unit and corrects calculation results from the calculation unit based on a difference between a plurality of the mark position information calculated by the calculation unit using the plurality of processing information, wherein

of the plurality of mark position information, if a first position information is termed CH, a second position information is termed CL, and a predetermined coefficient is termed R (R>

0),

the first position information CH is calculated from a higher resolution signal than the second position information CL, and

the correction unit performs corrections based on a result determined by (CL−

CH)×

R.

2. A position measuring device according to claim 1, wherein

the predetermined information is the mark signal,

the processing unit performs processing on the mark signal and alters a proportion within the mark signal of a frequency component of a predetermined frequency range, and generates a mark signal having a different frequency configuration from the mark signal, and

the correction unit performs the corrections based on a plurality of mark signal information calculated by the calculation unit using a plurality of mark signals.

3. A position measuring device according to claim 2, wherein the processing unit performs alteration processing of a frequency configuration of the mark signal using a predetermined frequency gain distribution.

4. A position measuring device according to claim 2, wherein the calculation unit calculates the plurality of mark position information by either one of performing a reflective autocorrelation for each of the plurality of mark signals having different frequency configurations, and performing template matching of the plurality of mark signals using a template having a predetermined frequency configuration.

5. A position measuring device according to claim 2, wherein the processing unit generates a plurality of mark signals having different frequency configurations by in addition to the processing on the mark signal for altering a proportion within the mark signal of the frequency component of the predetermined range, also performing processing which alters a proportion, within the mark signal, of a frequency component of a range for which at least a portion thereof differs from the predetermined range.

6. A position measuring device according to claim 1, wherein

the predetermined information is the mark signal,

the processing unit calculates a phase of each different frequency component of the mark signal, and

the correction unit performs the corrections based on a plurality of mark position information calculated from a plurality of phases.

7. A position measuring device according to claim 6, wherein

the processing unit performs a Fourier transformation on the mark signal and calculates phases of Fourier components of different order, and

the correction unit performs the corrections based on the plurality of mark position information calculated from phases of the Fourier components of different order.

8. A position measuring device according to claim 1, wherein

the calculation unit calculates the plurality of mark position information by performing template matching on the mark signal using a template having a predetermined frequency configuration,

the predetermined information is either one of a correlation function calculated from the template and the mark signal, and the template,

the processing unit performs processing which alters a proportion of a frequency component of a predetermined frequency range for either one of the template and the correlation function, and generates either one of a plurality of templates with different frequency configurations and a plurality of correlation functions, and

the correction unit performs the corrections based on a plurality of mark position information calculated by the calculation unit using either one of the plurality of templates and the plurality of correlation functions.

9. A position measuring device according to claim 1, wherein the higher resolution signal incorporates a higher frequency component than a frequency component of a signal used when obtaining the second position information CL.

10. An exposure apparatus which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, comprising:

a position measuring device according to claim 1 is provided as a position measuring device which measures a position of at least one of the mask mark and the substrate mark.

11. A superposition measuring device which measures a superposition error between a plurality of measurement targets comprising a plurality of marks formed on individual layers on a substrate, comprising:

a position measuring device according to claim 1 is provided as a position measuring device which measures positions of the marks.

12. A position measuring device comprising a calculation unit which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object,

wherein the mark signal includes phases of diffracted light of different orders generated from the mark, and

the position measuring device further comprises a correction unit which is electrically connected to the calculation unit and corrects calculation results from the calculation unit based on a difference between a plurality of the mark position information calculated from a plurality of the phases, wherein

of the plurality of mark position information, if a first position information is termed CH, a second position information is termed CL, and a predetermined coefficient is termed R (R>

0),

the first position information CH is calculated from a higher resolution signal than the second position information CL,

the correction unit performs corrections based on a result determined by (CL−

CH)×

R, and

the higher resolution signal incorporates a higher frequency component than a frequency component of a signal used when obtaining the second position information CL.

13. An exposure apparatus which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, comprising:

a position measuring device according to claim 12 is provided as a position measuring device which measures a position of at least one of the mask mark and the substrate mark.

14. A superposition measuring device which measures a superposition error between a plurality of measurement targets comprising a plurality of marks formed on individual layers on a substrate, comprising:

a position measuring device according to claim 12 is provided as a position measuring device which measures positions of the marks.

15. A position measuring device comprising a calculation unit which calculates mark position information relating to a position of a mark formed on an object, by performing template matching between a template having a predetermined frequency configuration and a mark signal obtained by irradiating a detection beam onto the mark, wherein the position measuring device further comprises:

a filtering unit which performs either one of a first filtering process which reduces a proportion within the mark signal of a frequency component less than a specified frequency and reduces a proportion within the template of a frequency component less than the specified frequency, and a second filtering process which reduces a proportion of a frequency component less than the specified frequency on a correlation function calculated from the template and the mark signal, and

the calculation unit is electrically connected to the filtering unit and calculates the mark position information by either one of performing template matching on the mark signal and the template which have been subjected to the first filtering process, and basing calculations on correlation function which has been subjected to the second filtering process,

wherein the filtering unit reduces a proportion of a frequency component within the mark signal having a basic frequency defined based on a shape of the mark, less than a proportion of a frequency component within the mark signal having a frequency greater than the basic frequency.

16. A position measuring device according to claim 15, wherein the basic frequency in a multi-mark incorporating a plurality of line patterns is 1/MP, where MP refers to a mark pitch showing a spacing between each line pattern, and the basic frequency in a single mark made up of only a single line pattern is ½

MW, where MW refers to a width of the single line pattern.

17. An exposure apparatus which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, comprising:

a position measuring device according to claim 15 is provided as a position measuring device which measures a position of at least one of the mask mark and the substrate mark.

18. A superposition measuring device which measures a superposition error between a plurality of measurement targets comprising a plurality of marks formed on individual layers on a substrate, comprising:

a position measuring device according to claim 15 is provided as a position measuring device which measures positions of the marks.

19. A position measuring device comprising a calculation unit which calculates mark position information relating to a position of a mark formed on an object, by performing folded autocorrelation of a mark signal obtained by irradiating a detection beam onto the mark, wherein the position measuring device further comprises:

a filtering unit which performs filtering processing that reduces a proportion within the mark signal of a frequency component less than a specified frequency, and

the calculation unit is electrically connected to the filtering unit and calculates the mark position information by performing a folded autocorrelation of the mark signal which has undergone the filtering processing,

wherein the filtering unit reduces a proportion of a frequency component within the mark signal having a basic frequency defined based on a shape of the mark, less than a proportion of a frequency component within the mark signal having a frequency greater than the basic frequency.

20. An exposure apparatus which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, comprising:

a position measuring device according to claim 19 is provided as a position measuring device which measures a position of at least one of the mask mark and the substrate mark.

21. A superposition measuring device which measures a superposition error between a plurality of measurement targets comprising a plurality of marks formed on individual layers on a substrate, comprising:

a position measuring device according to claim 19 is provided as a position measuring device which measures positions of the marks.

22. A position measuring device comprising a calculation unit which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object, wherein the position measuring device further comprises:

a filtering unit which performs filtering processing of the mark signal, and generating a plurality of mark signals having different frequency configurations, and

an extraction unit which is electrically connected to the filtering unit and extracts, from a plurality of mark position information calculated by the calculation unit using the plurality of mark signals, mark position information satisfying a predetermined condition, and

a final mark position information is determined based on the extracted mark position information,

wherein the extraction unit extracts mark position information calculated based on a mark signal incorporating a larger low frequency component if a difference between the plurality of mark position information is greater than a predetermined value, and extracts mark position information calculated based on a mark signal incorporating a larger high frequency component if the difference is less than or equal to the predetermined value.

23. An exposure apparatus which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, comprising:

a position measuring device according to claim 22 is provided as a position measuring device which measures a position of at least one of the mask mark and the substrate mark.

24. A superposition measuring device which measures a superposition error between a plurality of measurement targets comprising a plurality of marks formed on individual layers on a substrate, comprising:

a position measuring device according to claim 22 is provided as a position measuring device which measures positions of the marks.

25. A position measuring device comprising a calculation unit which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object, wherein the position measuring device further comprises:

a filtering unit which performs filtering processing of the mark signal, and generating a plurality of mark signals having different frequency configurations, and

an extraction unit which is electrically connected to the filtering unit and extracts, from a plurality of mark position information calculated by the calculation unit using the plurality of mark signals, mark position information satisfying a predetermined condition, and

a final mark position information is determined based on the extracted mark position information, wherein

the filtering unit reduces a proportion within the mark signal of a frequency component greater than a specified frequency, and

in a case where the filtering processing is performed a plurality of times on the mark signal, the filtering is performed following an alteration of the frequency component for which a proportion is to be reduced.

26. A position measuring method comprising a calculation step which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object,

wherein the calculation step performs predetermined processing on predetermined information to be used when calculating the mark position information, and generates a plurality of processing information, and

the position measuring method further includes correcting calculation results from the calculation step based on a difference between a plurality of the mark position information calculated by the calculation step using the plurality of processing information, wherein

of the plurality of mark position information, if a first position information is termed CH, a second position information is termed CL, and a predetermined coefficient is termed R (R>

0),

the first position information CH is calculated from a higher resolution signal than the second position information CL, and

corrections are performed based on a result determined by (CL−

CH)×

R.

27. A position measuring method according to claim 26, wherein the predetermined information is the mark signal,

the position measuring method further comprises:

performing processing on the mark signal which alters a proportion within the mark signal of a frequency component of a predetermined frequency range, and generates a mark signal having a different frequency configuration from the mark signal, and

performing the corrections based on a plurality of mark signal information calculated by the calculation step using a plurality of mark signals.

28. A position measuring method according to claim 27, wherein alteration processing of a frequency configuration of the mark signal is performed using a predetermined frequency gain distribution.

29. A position measuring method according to claim 27, further comprising:

performing a Fourier transformation on the mark signal and calculating phases of Fourier components of different order, and

performing the corrections based on the plurality of mark position information calculated from phases of the Fourier components of different order.

30. An exposure method which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, including:

a position measuring method according to claim 26 as a position measuring method which measures a position of at least one of the mask mark and the substrate mark.

31. A superposition measuring method which measures a superposition error between a plurality of measurement targets comprising a plurality of marks formed on individual layers on a substrate, comprising:

a position measuring method according to claim 26 as a position measuring method which measures positions of the marks.

32. A position measuring method comprising a calculation step which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object,

wherein the mark signal includes phases of diffracted light of different orders generated from the mark, and

calculation results from the calculation step are corrected based on a difference between a plurality of mark position information calculated from a plurality of phases, wherein

of the plurality of mark position information, if a first position information is termed CH, a second position information is termed CL, and a predetermined coefficient is termed R (R>

0),

the first position information CH is calculated from a higher resolution signal than the second position information CL, and

corrections are performed based on a result determined by (CL−

CH)×

R.

33. An exposure method which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, including:

a position measuring method according to claim 32 as a position measuring method which measures a position of at least one of the mask mark and the substrate mark.

34. A position measuring method using a calculation unit which calculates mark position information relating to a position of a mark formed on an object, by performing template matching between a template having a predetermined frequency configuration and a mark signal obtained by irradiating a detection beam onto the mark, the position measuring method comprising:

carrying out either one of a first filtering process which reduces a proportion within the mark signal of a frequency component less than a specified frequency and reducing a proportion within the template of a frequency component less than the specified frequency, and a second filtering process which reduces a proportion of a frequency component less than the specified frequency on a correlation function calculated from the template and the mark signal, wherein in the first or second filtering process, within the mark signal, a proportion of a frequency component within the mark signal having a basic frequency defined based on a shape of the mark is reduced even more than a proportion of a frequency component within the mark signal having a frequency greater than the basic frequency, and

the calculation unit calculates the mark position information by either one of performing template matching on the mark signal and the template which have been subjected to the first filtering process, and basing calculations on the correlation function which has been subjected to the second filtering process.

35. A position measuring method according to claim 34, wherein the basic frequency in a multi-mark incorporating a plurality of line patterns is 1/MP, where MP refers to a mark pitch showing a spacing between each line pattern, and the basic frequency in a single mark made up of only a single line pattern is ½

MW, where MW refers to a width of the single line pattern.

36. An exposure method which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, including:

a position measuring method according to claim 34 as a position measuring method which measures a position of at least one of the mask mark and the substrate mark.

37. A position measuring method using a calculation unit which calculates mark position information relating to a position of a mark formed on an object, by performing folded autocorrelation of a mark signal obtained by irradiating a detection beam onto the mark, the position measuring method comprising:

performing filtering processing which reduces a proportion within the mark signal of a frequency component less than a specified frequency, wherein in the filtering processing, within the mark signal, a proportion of a frequency component within the mark signal having a basic frequency defined based on a shape of the mark is reduced even more than a proportion of a frequency component within the mark signal having a frequency greater than the basic frequency, and

the calculation unit calculates the mark position information by performing a folded autocorrelation of the mark signal which has undergone the filtering processing.

38. A position measuring method according to claim 37, wherein the basic frequency in a multi-mark incorporating a plurality of line patterns is 1/MP, where NIP refers to a mark pitch showing a spacing between each line pattern, and the basic frequency in a single mark made up of only a single line pattern is ½

MW, where MW refers to a width of the single line pattern.

39. An exposure method which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, including:

a position measuring method according to claim 37 as a position measuring method which measures a position of at least one of the mask mark and the substrate mark.

40. A position measuring method using a calculation unit which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object, the position measuring method comprising:

performing filtering processing of the mark signal, and generating a plurality of mark signals having different frequency configurations, and

extracting, from a plurality of mark position information calculated by the calculation unit using the plurality of mark signals, mark position information satisfying a predetermined condition, and

determining a final mark position information based on the extracted mark position information, wherein

the filtering processing reduces a proportion within the mark signal of a frequency component greater than a specified frequency, and

in a case where the filtering processing is performed a plurality of times on the mark signal, the filtering is performed following an alteration of the frequency component for which a proportion is to be reduced.

41. A position measuring method according to claim 40, further comprising:

extracting mark position information calculated based on a mark signal incorporating a larger low frequency component if a difference between the plurality of mark position information is greater than a predetermined value, and extracting mark position information calculated based on a mark signal incorporating a larger high frequency component if the difference is within the predetermined value.

42. An exposure method which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, including:

a position measuring method according to claim 40 as a position measuring method which measures a position of at least one of the mask mark and the substrate mark.

43. A position measuring method using a calculation unit which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object, the position measuring method comprising:

comparing mark position information calculated by the calculation unit based on the mark signal and a predetermined design value information relating to the mark, and then judging acceptability of the calculated mark position information,

performing filtering processing of the mark signal, and generating a mark processed signal having a different frequency configuration from the mark signal subjected to the filtering processing, and

in a case where acceptability of the mark signal is denied by the judgment, calculating the mark position information by the calculation unit using the generated mark processed signal, and judging acceptability of the mark position information, and repeating the filtering processing, the calculating of mark position information based on the mark processed signal, and the judging until acceptability of mark position information calculated by the calculation unit is approved, wherein

the filtering processing reduces a proportion within the mark signal of a frequency component greater than a specified frequency, and

in a case where the filtering processing is performed a plurality of times on the mark signal, the filtering is performed following an alteration of the frequency component for which a proportion is to be reduced.

44. An exposure method which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, including:

a position measuring method according to claim 43 as a position measuring method which measures a position of at least one of the mask mark and the substrate mark.

45. A position measuring method using a calculation unit which calculates mark position information relating to a position of a mark by using a mark signal obtained by irradiating a detection beam onto the mark formed on an object, the position measuring method comprising:

performing filtering processing on the mark signal, and generating a mark signal having a different frequency configuration,

comparing a plurality of mark position information calculated by the calculation unit using a plurality of mark signals having different frequency configurations, and evaluating the mark position information, and

the calculation unit calculates a final mark position information based on the plurality of mark position information and evaluation results, wherein

the filtering processing reduces a proportion within the mark signal of a frequency component greater than a specified frequency, and

in a case where the filtering processing is performed a plurality of times on the mark signal, the filtering is performed following an alteration of the frequency component for which a proportion is to be reduced.

46. A position measuring method according to claim 45, wherein the mark is a multi-mark in which a plurality of mark elements are aligned periodically in a predetermined direction, the position measuring method comprising:

evaluating position information of each mark element based on differences between position information of each mark element within the plurality of mark position information, and

determining a weighting for position information of each mark element when calculating a final position information using position information of each of the mark elements.

47. A position measuring method according to claim 45, wherein a plurality of marks are formed on the object, the position measuring method comprising:

performing the filtering processing on a plurality of target marks for measurement from amongst the plurality of marks, and generating a mark signal having a different frequency configuration for each of the target marks for measurement,

evaluating the mark position information determined for each of the target marks for measurement, and

calculating position information for each of the plurality of marks formed on the object by a statistical calculation using evaluation results and the mark position information for each of the target marks for measurement.

48. An exposure method which aligns a mask and a substrate by using a mask mark on the mask and a substrate mark on the substrate, and then exposes a pattern of the mask onto the substrate, including:

a position measuring method according to claim 45 as a position measuring method which measures a position of at least one of the mask mark and the substrate mark.