Alignment method

• US 5,805,866 A
• Filed: 03/24/1997
• Issued: 09/08/1998
• Est. Priority Date: 02/10/1994
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Magome, Nobutaka, Mizutani, Shinji
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): LOPPNOW, MATTHEW CLAY
• Application Number:
  US08/826,064
• Time in Patent Office: 533 Days
• Field of Search: 364/578, 364/489, 364/490, 364/491, 364/559, 355/53, 356/375, 356/401, 395/500
• US Class Current: 716/51
• CPC Class Codes: G03F 7/70858 Environment aspects, e.g. pressure of beam-path gas, temperature pollution aspects G03F7/70916
• CPC Class Codes: G03F 9/70 for microlithography measuring printed patterns for monitoring overlay G03F7/70633 or focus G03F7/70641; projection system adjustment G03F7/70258; position control G03F7/70775
• CPC Class Codes: H01L 21/68 for positioning, orientation or alignment

Abstract

An alignment method for achieving accurate alignment by accurately eliminating an isolated area with a large nonlinear component of an alignment error from sample areas. A conversion parameter is calculated by statistical processing on the basis of a result obtained by measuring the position of each sample area on a substrate to be processed in advance, and each area on the substrate is aligned on the basis of arrangement coordinate values calculated using the conversion parameter. This method relates to a method of aligning each of a plurality of areas to be processed arranged on the substrate on the basis of arrangement coordinates on a first coordinate system (x, y) set on the substrate to a predetermined process position in a second coordinate system (X, Y) for defining the moving position of the substrate.

Claims

1. A method of aligning each of a plurality of areas on a substrate to a predetermined position in a coordinate system for defining a moving position of said substrate, comprising:

a first step of measuring coordinate positions, on the coordinate system, of N (N is an integer not less than

     2) sample areas selected from the plurality of areas;

a second step of calculating nonlinear deviation amounts of the coordinate positions of the N sample areas on the basis of the coordinate positions measured in the first step;

a third step of calculating nonlinear deviation amounts of coordinate positions of (N-1) sample areas, obtained by rejecting one sample area from the N sample areas, on the basis of the coordinate positions measured in the first step; and

a fourth step of rejecting said one sample area from the plural sample areas for calculating coordinate positions, on the coordinate system, of each of plural sample areas when the variation of said (N-1) nonlinear deviation amounts calculated in the third step is smaller than the variation of said (N) nonlinear deviation amounts calculated in the second step.

3. A method according to claim 1, wherein in the fourth step, when the variation of said (N-1) nonlinear deviation amounts calculated in the third step is smaller than the variation of said (N) nonlinear deviation amounts calculated in the second step, said (N-1) sample areas are selected as sample areas for calculation, and when the variation of the (N-1) nonlinear deviation amounts calculated in the third step is not less than the variation of the N nonlinear deviation amounts calculated in the second step, said (N) sample areas are selected as sample areas for calculation.

4. A method according to claim 3, further comprising:

a fifth step of calculating coordinate positions, on the coordinate system, of said selected sample areas for calculation by executing statistical processing of the coordinate positions, measured in the first step, said substrate being moved according to the calculated coordinate position thereby each of said plural areas is aligned to said predetermined position sequentially.

5. A method according to claim 4, further comprising:

a sixth steps of moving said substrate according to said calculated coordinate positions by step-and repeat method or step-and-scanning method so that each of said plural areas is exposed against a pattern image of a mask.

6. A method according to claim 3, wherein coordinate positions, on the coordinate system, of one of the plurality of areas are calculated by executing statistical processing of the coordinate positions measured in the first step in consideration of weight corresponding to the distance between each of the selected sample areas for calculation and said one of the plurality of areas.

7. A method according to claim 1, wherein in the fourth step when the variation of the (N-1) nonlinear deviation amounts calculated in the third step is smaller than the variation of the N nonlinear deviation amounts calculated in the second step, the N sample areas in the second step are replaced by the (N-1) sample areas used in the third step, and the second to fourth steps are repeated.

8. A method according to claim 7, wherein the second to fourth steps are repeated within a range in which the number of sample areas other than sample areas rejected in the fourth step is not less than a predetermined tolerance value.

9. A method according to claim 1, wherein in the third step, N variations of the nonlinear deviation amounts are obtained with respect to the N-1 sample areas, selecting one sample area to be rejected from the N sample areas in each of the N sample areas and in the fourth step, one sample area with which the variation of (N-1) nonlinear deviation amounts in the N sample areas is minimum and is smaller than that of the N nonlinear deviation amounts is rejected from sample areas for calculation.

10. A method according to claim 9, wherein in the fourth step, the obtained N variations are not respectively less than those the variation of the N nonlinear deviation amounts, the N sample areas are selected as sample areas.

11. A method according to claim 9, wherein when, in the fourth step, at least one of the N variations is smaller than the variation of the N nonlinear deviation amounts, the N sample areas of the second step are replaced with the N-1 sample areas of the third step and the second to fourth steps are repeated.

12. A method according to claim 1, wherein said second step includes the sub-steps of:

calculating the coordinate position, on said coordinate system, of each of the N sample areas by executing statistical processing of the measured coordinate positions of the N-1 sample areas; and

obtaining a deflection amount between the measured coordinate position and the calculated coordinate position in each of the N sample areas, as the nonlinear deviation amount.

13. A method according to claim 1, wherein said third step includes the sub-steps of:

calculating the coordinate position, on said coordinate system, of each of the N-1 sample areas by executing statistical processing of the measured coordinate positions of the N-1 sample areas; and

obtaining a deflection amount between the measured coordinate position and the calculated coordinate position in each of the N-1 sample areas, as the nonlinear deviation amount.

2. A method of aligning each of a plurality of areas on a substrate to a predetermined position in a coordinate system for defining a moving position of said substrate, comprising:

a first step of measuring coordinate positions, on the coordinate system, of N (N is an integer not less than

     2) sample areas selected from the plurality of areas;

a second step of calculating nonlinear deviation amounts of the coordinate positions of the N sample areas on the basis of the coordinate positions measured in the first step;

a third step of calculating nonlinear deviation amounts of coordinate positions of (N-1) sample areas obtained by rejecting one sample area from the N sample areas based on the coordinate positions measured in the first step; and

a fourth step of selecting said one sample area as a sample area for calculating coordinate positions, on the coordinate system, of each of plural sample areas when the variation of the (N-1) nonlinear deviation amounts calculated in the third step is not less than the variation of the N nonlinear deviation amounts calculated in the second step.

14. A method of aligning each of a plurality of areas on a substrate to a predetermined position in a coordinate system for defining a moving position of the substrate, comprising:

a first step of measuring coordinate positions, on the coordinate system, of N (N is an integer not less than

     2) sample areas selected from the plurality of areas;

a second step of calculating nonlinear deviation amount of the coordinate positions of the (N-1) sample areas obtained by sequentially rejecting an i-th (i is an integer from 1 to N) sample area from the N sample areas on the basis of the coordinate positions measured in the first step thereby to obtain N variations;

a third step of determining sample areas for calculation of the coordinate position, on said coordinate system, of each of the plural areas based on the N variations.

15. A method according to claim 14, wherein in the third step, one sample area, of the N sample areas, in which said variation is minimum, is rejected from the sample areas for calculation.

16. A method according to claim 14, further comprising:

a fourth step of calculating coordinate positions, on the coordinate system, of said selected sample areas for calculation by executing statistical processing of the coordinate positions, measured in the first step, said substrate being moved according to the calculated coordinate position thereby each of said plural areas is aligned to said predetermined position sequentially.

17. A method according to claim 16, further comprising:

a fifth steps of moving said substrate according to said determined coordinate positions by step-and repeat method or step-and-scanning method so that each of said plural areas is exposed against a pattern image of a mask.

18. A method according to claim 14, wherein said second step includes the sub-steps of:

calculating the coordinate position, on said coordinate system, of each of the N-1 sample areas by executing statistical processing of the measured coordinate positions of the N-1 sample areas; and

obtaining a deflection amount between the measured coordinate position and the calculated coordinate position in each of the N-1 sample areas, as the nonlinear deviation amount.

27. A method according to claim 14, wherein in said third step, said N sample areas are selected as said sample areas calculation when each of said N variations is not less than the variation of N nonlinear deviation amounts of coordinate positions of said N sample areas.

28. A method according to claim 14, wherein in said third step, one sample area is rejected from said sample areas for calculation, said one sample area having the variation thereof which is not more than the variation of N nonlinear deviation amount of coordinate positions of said N sample areas.

29. A method according to claim 28, wherein said second and third steps are repeated until in said third step, J (J is an integer from 1 to N-4) sample areas are rejected from said N sample areas and thereafter N-J variations obtain in said second step are not less than the variations of nonlinear deviation amounts of (N-J+1) coordinate positions.

30. A method according to claim 15, wherein said second and third steps are repeated until the variations obtained in said second are predetermined allowable ranges respectively.

31. A method according to claim 15, wherein said N sample areas consists of said plurality of areas on said substrate.

19. A method of aligning each of a plurality of areas on a substrate to a predetermined position in a coordinate system for defining a moving position of the substrate, comprising:

a first step of measuring coordinate positions, on the coordinate system, of N (N is an integer not less than

     2) sample areas selected from the plurality of areas;

a second step of calculating the variation of nonlinear deviation amounts of the coordinate positions of the N sample areas and the variation of nonlinear deviation amounts of N-1 sample areas in which one sample area is rejected from the N sample area on the basis of the coordinate positions measured in the first step;

a third step of rejecting the one sample area from the sample areas for calculating the coordinate positions, on the coordinate system, of the plural areas when the variation of the nonlinear deviation amounts if the N-1 sample areas is smaller than that of the N sample areas.

20. A method of aligning each of a plurality of areas on a substrate to a predetermined position in a coordinate system for defining a moving position of the substrate, comprising:

a first step of measuring coordinate positions, on the coordinate system, of N (N is an integer not less than

     2) sample areas selected from the plurality of areas;

a second step of calculating the variation of nonlinear deviation amounts of the coordinate positions of the N sample areas on the basis of the coordinate positions measured in the first step;

a third step of calculating the variation of nonlinear deviation amounts of N-1 sample areas in which one sample area is rejected from the N sample area on the basis of the coordinate positions measured in the first step;

a fourth step of rejecting the one sample area from the sample areas for calculating the coordinate positions, on the coordinate system, of the plural areas when the variation of the nonlinear deviation amounts if the N-1 sample areas is smaller than that of the N sample areas; and

a fifth step of, when the variation of the N-1 nonlinear deviation amounts is out of a predetermined tolerance region, rejecting the predetermined sample areas from the N sample areas and repeating from the second step to the fourth step.

21. A method according to claim 20, further comprising:

a sixth step of calculating coordinate positions, on the coordinate system, of said selected sample areas for calculation by executing statistical processing of the coordinate positions of the sample areas except for the sample areas rejected in the fourth step;

said substrate being moved according to the calculated coordinate position thereby each of said plural areas is aligned to said predetermined position sequentially.

22. A method according to claim 21, further comprising:

a seventh step of moving said substrate according to said calculated coordinate positions by step-and repeat method or step-and-scanning method so that each of said plural areas is exposed against a pattern image of a mask.

23. A method according to claim 20, wherein in the fifth step when the number of the sample areas except for the sample areas rejected in the fourth step is over a predetermined tolerance number, the second to fourth steps are repeated.

24. A method according to claim 20, wherein the tolerance region of the fifth step depends on the variation in measuring the coordinate positions, on the coordinate system, of the sample areas.

25. A method according to claim 20, wherein in the third step, N variations of the nonlinear deviation amounts are obtained with respect to the N-1 sample areas, selecting one sample area to be rejected from the N sample areas in each of the N sample areas and in the fourth step, one sample area with which the variation of (N-1) nonlinear deviation amounts in the N sample areas is minimum and is smaller than that of the N nonlinear deviation amounts is rejected from sample areas for calculation.

26. A method of aligning each of a plurality of areas on a substrate to a predetermined position in a predetermined coordinate system, comprising:

a first step of measuring coordinate positions on said coordinate system of each of N sample areas out of the plurality of areas, N being an integer not less than 2;

a second step of calculating nonlinear deviation amounts of the coordinate positions of each of said N sample areas on the basis of said measured coordinate positions;

a third step of calculating nonlinear deviation amounts of coordinate positions of (N-1) sample areas, obtained by rejecting one sample area from said N sample areas, on the basis of said measured coordinate positions; and

a fourth step of comparing the variation of said (N-1) nonlinear deviation amounts with the variation of said N nonlinear deviation amounts, and judging whether the coordinate positions of said one sample area should be rejected from the calculation of the coordinate positions, on said coordinate system, of each of said plurality of areas on said substrate, on the basis of result of the comparison.

32. A method of aligning each of a plurality of areas on a substrate to a predetermined position in a coordinate system, comprising the steps of:

measuring coordinate positions on the coordinate system of each of N sample areas among the plurality of areas; and

determining nonlinear deviation amounts of coordinate positions of (N-1) sample areas, obtained by rejecting one sample area from the N sample areas, based on the measured coordinate positions;

wherein at least three sample areas for calculation of coordinate positions of the plurality of areas are determined based on the (N-1) nonlinear deviation amounts.

33. A method according to claim 32, further comprising the step of:

moving said substrate based on said calculation of coordinate positions to expose each of said plurality of areas with a pattern.

34. A method of aligning each of a plurality of areas on a substrate to a predetermined position in a coordinate system, comprising the steps of:

measuring coordinate positions on the coordinate system of each of N sample areas among the plurality of areas; and

determining a standard deviation of nonlinear deviation amounts of (N-1) sample areas, obtained by rejecting one sample area from the N sample areas, based on the measured coordinate positions,

wherein at least three sample areas for calculation of coordinate positions of the plurality of areas are determined based on the determined standard deviations.