Method of and apparatus for detecting plane position

• US 5,502,311 A
• Filed: 04/13/1995
• Issued: 03/26/1996
• Est. Priority Date: 01/17/1992
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Imai, Yuji, Tanaka, Yasuaki, Wakamoto, Shinji
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Dudek, James A.
• Application Number:
  US08/421,026
• Time in Patent Office: 348 Days
• Field of Search: 250/548, 250/557, 356/400, 356/401
• US Class Current: 250/548
• CPC Class Codes: G03F 7/70858 Environment aspects, e.g. pressure of beam-path gas, temperature pollution aspects G03F7/70916
• CPC Class Codes: G03F 7/70883 of optical system
• CPC Class Codes: G03F 9/7026 Focusing
• CPC Class Codes: G03F 9/7034 Leveling

Abstract

A plane positioning apparatus comprises a projector for projecting beams to a given portion on the surface of a substrate in a diagonal direction, a light receiving device to receive beams reflected from the substrate surface and output photoelectric signals in accordance with variation of the light receiving position, a calculating circuit to output deviation signals in accordance with the deviation amount of the substrate surface with respect to a predetermined fiducial plane based on the deviation signals, a substrate shifting device to shift and set the substrate at a given position in a direction perpendicular to the fiducial plane in accordance with the deviation signals, a level variation detecting device to detect level variation of the deviation signals generated when the substrate surface and the fiducial plane are displaced interrelatedly, an inclination calculating device to calculate, in accordance with the level variation characteristics, the value of the inclination of the level variation characteristics at a point where the substrate surface and the fiducial plane are substantially matched, and a correction device to correct the allowable range set for the level variation characteristics in order to control the substrate shifting device in accordance with the difference between the inclination value and the fiducial value thus calculated.

Claims

1. A plane positioning apparatus comprising:

a projection system for projecting a beam to a given portion on a substrate surface;

a light receiving system for receiving a reflective beam from said substrate surface to output a photoelectric signal corresponding to variation of the light receiving position;

a calculating circuit to output a deviation signal corresponding to a deviation amount of said substrate surface from a predetermined fiducial plane in accordance with said photoelectric signal;

a substrate shifting system for shifting and setting said substrate to a given position in a direction perpendicular to said fiducial plane in accordance with said deviation signal;

a detecting device for detecting level variation of said deviation signal generated at a time of displacing said substrate surface and said fiducial plane interrelatedly within a range having substantially a linear relationship with said deviation amount;

a calculating device for calculating a value of inclination of level variation characteristics at a point where said substrate surface and said fiducial plane are substantially matched in accordance with said level variation characteristics; and

a correcting device for correcting an allowable range set for said level variation characteristics in accordance with said calculated value of inclination in order to control said substrate shifting system.

2. A plane positioning apparatus of claim 1, wherein

said correcting device includes an offset generating member for giving an offset corresponding to a deviation between a target plane where said substrate surface is to be set and said substrate surface to at least one of said light receiving system, said calculating circuit, and said substrate shifting system.

3. A plane positioning apparatus comprising:

a projecting system for projecting beams to a plurality of given portions on a substrate surface;

a light receiving system including a plurality of photoelectric elements to receive individually reflective beams respectively from a plurality of given portions on said substrate surface and output photoelectric signals in accordance with variation of light receiving positions;

a calculating circuit for outputting individually deviation signals in accordance with each of deviation amounts with respect to a fiducial plane predetermined at a plurality of given portions on said substrate surface based on each of said plural photoelectric signals;

a shifting system for shifting said substrate in a direction perpendicular to said fiducial plane or a direction inclined to said fiducial plane in accordance with at least one of said deviation signals;

a detecting device for individually detecting level variation characteristics of each deviation signal generated at a time of displacing each of a plurality of given portions on said substrate surface and said fiducial plane in a direction perpendicular to said fiducial plane interrelatedly within a range having substantially a linearly relationship with said deviation amounts;

a calculating device for calculating each of values of inclination of said level variation characteristics at a point where each of a plurality of given portions on said substrate surface is substantially matched with said fiducial plane; and

a correcting device for individually correcting an allowable level variation range set for each of said level variation characteristics in accordance with a calculated value of inclination for each of said plurality of given portions in order to make uniform an allowable range of deviation values for each of said plurality of given portions.

4. A plane positioning apparatus comprising:

a shifting system for holding a substrate to be positioned substantially in parallel to a given fiducial plane and shifting the substrate in a direction perpendicular to said fiducial plane;

a multipoint measuring system having a plurality of measuring points set on a surface of said substrate to measure positional deviation amounts from said fiducial plane at said measuring points with respect to a direction perpendicular to said fiducial plane and output deviation signals corresponding to said deviation amounts at said measuring points;

a controller for controlling said shifting system in accordance with at least one of the deviation signals output at said measuring points;

a detecting device for detecting a ratio of level variation of said deviation signals with respect to variation of said deviation amounts for each of said measuring points; and

a setting device for individually setting an allowable range of the level variation of said deviation signals at said measuring points in accordance with a detected rate of change per measuring point so as to make an allowable deviation amount from said fiducial plane substantially equal at each of the measuring points on said substrate when said substrate is positioned by said shifting system.

5. A plane positioning apparatus of claim 4, wherein

a pattern image of a mask substrate is provided for a projection exposure apparatus for imaging on a photosensitive substrate by projection through an optical projection system, and

said shifting system sets a position of either one of said mask substrate and said photosensitive substrate with regard to a plane perpendicular to an optical axis of said optical projection system as said fiducial plane.

6. A plane positioning apparatus of claim 5, wherein

said projection exposure apparatus has a Z stage to hold said photosensitive substrate and cause it to be shifted in the direction of the optical axis of said optical projection system, and a fiducial board is arranged on said Z stage with the fiducial marks being formed thereon to measure the inclination or curvature of the projected image of said optical projection system with respect to said fiducial plane when said mask substrate is installed.

7. A projection exposure apparatus comprising:

an optical projection system to project and image a mask pattern in a given imaging surface;

an XY stage to hold a photosensitive substrate substantially in parallel with said imaging surface and to be shifted two dimensionally in a plane parallel to said imaging surface;

a Z stage to shift said photosensitive substrate in a direction of an optical axis of said optical projection system;

a first focus detecting system having measuring points at plural positions predetermined in a projection field of said optical projection system to detect a positional deviation of a surface of said photosensitive substrate in the direction of the optical axis at each of said measuring points;

a fiducial board arranged on a part of said Z stage with a light emitting portion being formed thereon to emit light with a given configuration;

a second focus detecting system for detecting a positional relationship of said fiducial board in the direction of the optical axis with said imaging surface in such a manner that when said light emitting portion is positioned at an arbitrary point in said projection field, rays of light reflected by said mask return to said fiducial board through said optical projection system, among those rays of light from said light emitting portion to reach said mask through said optical projection system, and are photoelectrically detected by shifting said Z stage;

a specifying device for specifying coordinate positions of said XY stage so that said light emitting portion is positioned in turn in each of the measuring points or positions close thereto by said first focus detecting system; and

a calibrating system for calibrating detection errors by said first focus detecting system individually or averagely at each of said measuring points in accordance with each positional relationship detected by operating said second focus detecting system at each of the specified coordinate position.

8. A method for detecting plane positions comprising:

measuring a positional deviation amount between a given fiducial plane and an inspecting surface in a direction perpendicular to said fiducial plane at each of plural measuring points set on the inspecting surface;

classifying said plural measuring points into at least two groups in accordance with a surface condition within said inspecting surface, at the same time determining weighting coefficients to be given to said deviation amounts per group; and

detecting a position of said inspecting surface in a direction perpendicular to said fiducial plane by giving said determined weighting coefficients to said deviation amounts, at the same time averaging a sum of deviation amounts subsequent to said giving of weighting coefficients.

9. An apparatus for detecting plane positions comprising:

a projection system for projecting a pattern light on an inspecting surface;

a light receiving system for receiving said pattern light reflected by said inspecting surface to output signals corresponding to the pattern light;

an input device for inputting information regarding position of said inspecting surface to be measured;

a selecting device for dividing a pattern image into a plurality of portions to selectively detect at least two portions of said pattern image in accordance with the information from said input device;

a first position detecting system for output ting a first detection signal corresponding to a height position of said inspecting surface for each of said pattern image portions;

a weighting device to give a weighting coefficient to weight each of said first detection signals; and

a second position detecting system for averaging a sum of said weighted signals by a sum of the weighting coefficients so that a second detection signal corresponding to the height of said inspecting surface is outputted.

10. An apparatus for detecting plane positions of claim 9, wherein

said weighting device includes a determining device for determining at least one of said weighting coefficients to be different from other weighting coefficients.

11. An apparatus for detecting plane positions comprising:

a projection system for projecting a pattern light on an inspecting surface;

a light receiving system for receiving said pattern light reflected by said inspecting surface to output signals corresponding to a pattern light receiving position;

an input device for inputting information regarding a position of said inspecting surface to be measured;

a selecting device for dividing a pattern image into a plurality of portions to selectively detect at least two portions of said pattern image in accordance with the information from said input device;

a first position detecting system for outputting a first detection signal corresponding to a height position of said inspecting surface for each of said portions of said pattern image;

a weighting device for classifying said pattern image portions into predetermined groups to give a weighting coefficient to weight each of signals obtained by averaging a sum of said first detection signals by a number of said pattern image portions in a group for each of said groups; and

a second position detecting system for averaging a sum of said weighted signals by a sum of the weighting coefficients so that a second detection signal corresponding to the height of said inspecting surface is outputted.

12. An apparatus for detecting plane positions comprising:

a multipoint measuring system having a plurality of measuring points set on an inspecting surface to measure positional deviation amounts from a fiducial plane at each of said plurality of measuring points with respect to a direction perpendicular to the fiducial plane, and output deviation signals corresponding to said deviation amounts at the measuring points;

a determining device for classifying said measuring points at least into two groups, at the same time determining weighting coefficients to weight said deviation signals for each of said groups; and

a position detecting system for giving said determined weighting coefficients to said deviation signals, and averaging a sum of the weighted signals so that a detection signal corresponding to the height of said inspecting surface is outputted.

13. An apparatus for detecting plane positions comprising:

a projection system for projecting a pattern light on an inspecting surface;

a light receiving system for receiving said pattern light reflected by said inspecting surface to output signals corresponding to a pattern light receiving portion;

an input device for inputting information regarding a position of said inspecting surface to be measured;

a first selecting device for dividing said pattern image into a plurality of portions to selectively detect at least two portions of said pattern image in accordance with the information from said input device;

a position detecting system for outputting detection signals corresponding to height positions of said inspecting surface for each of said pattern image portions;

a second selecting device for selecting at least two of said detection signals corresponding to local areas having substantially the same height positions on said inspecting surface; and

an inclination detecting system for detecting inclination of said inspecting surface from a difference between at least two detection signals selected by said second selection device.

14. An apparatus for detecting plane position of claim 13, wherein

said second selecting device selects at least two detection signals at least at each of two local areas on said inspecting surface, and

said inclination detecting system includes a calculating circuit to obtain said difference per each local area and sets an inclination of said inspecting surface to minimize a sum of the signal difference per each local area.

15. An apparatus for detecting plane positions comprising:

a multipoint detecting system having plural measuring points in a projection field of an optical projection system and detecting a deviation amount of a surface of a photosensitive substrate exposed with a mask pattern through the optical projection system in a direction of an optical axis of said optical projection system at each of said measuring points;

a stage capable of mounting said photosensitive substrate thereon, and movable in the direction of the optical axis of said optical projection system;

a first position detecting system for detecting first detection signals corresponding to deviation amounts of said substrate surface from an imaging plane of said optical projection system at each of at least two measuring points among said plural measuring points;

a weighting device for giving a weighting coefficient to weight each of said first detection signals; and

a second position detecting system for averaging a sum of the weighted signals by a sum of the weighting coefficients so that a second detection signal corresponding to a deviation amount of a predetermined plane of said substrate from said imaging plane is outputted.

16. An apparatus according to claim 15,

wherein said first position detecting system has a circuit for selecting at least two of the plural measuring points in accordance with a surface condition of said photosensitive substrate.

17. An apparatus for detecting plane positions comprising:

a multipoint detecting system having plural measuring points in a projection field of an optical projection system and detecting a deviation amount of a surface of a photosensitive substrate exposed with a mask pattern through the optical projection system in a direction of an optical axis of said optical projection system at each of said measuring points;

a stage capable of mounting said photosensitive substrate thereon, and movable in the direction of the optical axis of said optical projection system;

a first position detecting system for detecting first detection signals corresponding to deviation mounts of said substrate surface from an imaging plane of said optical projection system at each of at least two measuring points among said plural measuring points;

a weighting device for classifying said at least two measuring points into predetermined groups to give a weighting coefficient to weight each of signals obtainable by averaging a sum of said first detection signals by a number of said measuring points in a group for each of said groups; and

a second position detecting system for averaging a sum of the weighted signals by a sum of the weighting coefficients so that a second detection signal corresponding to a deviation amount of a predetermined plane of said substrate from said imaging plane is outputted.

18. An apparatus for detecting plane positions comprising:

a multipoint detecting system having plural measuring points in a projection field of an optical projection system and detecting a deviation amount of a surface of a photosensitive substrate exposed with a mask pattern through the optical projection system in a direction of an optical axis of said optical projection system at each of said measuring points;

a position detecting system for detecting detection signals corresponding to height positions of said substrate surface at each of at least two measuring points among said plural measuring points;

a selecting device for selecting at least two detection signals corresponding to said substrate surface having substantially the same height positions among said detection signals; and

an inclination detecting system for detecting inclination of said substrate surface in accordance with a difference between at least two detection signals selected by said selecting device.

19. An apparatus according to claim 18, further comprising:

a system for inclining said substrate in accordance with the detected inclination so that said surface of said substrate is made substantially parallel to an imaging plane of said projection optical system.

20. An apparatus according to claim 19,

wherein said inclining system comprises a leveling stage capable of holding and inclining said substrate, and a system for driving said leveling stage so that said surface of said substrate is made substantially parallel to said imaging plane of said projection optical system.

21. An apparatus according to claim 18,

wherein said position detecting system has a circuit for selecting at least two of the plural measuring points in accordance with a surface condition of said photosensitive substrate.

22. A projection exposure apparatus comprising:

a projection optical system for imaging and projecting a pattern of a mask onto a photosensitive substrate;

a substrate stage holding said photosensitive substrate thereon and inclinable with respect to an imaging plane of said projection optical system;

an inclination detecting system for detecting inclination of a surface of said photosensitive substrate independently of said projection optical system;

a pattern board provided on said substrate stage and having a predetermined fiducial pattern;

an illuminating system for applying illuminating light of substantially the same wavelength as that of illuminating light for exposure from an underside of said pattern board to said fiducial pattern;

a photoelectric detector for receiving light created from said fiducial pattern and applied to a pattern surface of said mask through said projection optical system and reflected by said pattern surface and returned through said projection optical system and said fiducial pattern;

a detecting system for detecting a focus position of said projection optical system based on a detection signal output from said photoelectric detector when said pattern board and the imaging plane of said projection optical system are moved relative to each other in a direction of an optical axis of said projection optical system;

a calculating device for finding the imaging plane of said projection optical system based on a focus position at each of a plurality of different positions in a projection field of said projection optical system;

a controller for controlling inclination of said substrate stage in conformity with the found imaging plane so that the imaging plane of said projection optical system and a surface of said pattern board may substantially coincide with each other; and

a calibrating system for calibrating said inclination detecting system so that said inclination detecting system may detect the surface of said pattern board as a fiducial surface when the imaging plane of said projection optical system and the surface of said pattern board are made substantially coincident with each other by said controller.

23. A projection exposure apparatus comprising:

a projection optical system for imaging and projecting a pattern of a mask onto a photosensitive substrate;

a substrate stage holding said photosensitive substrate thereon and movable in a direction of an optical axis of said projection optical system and a direction perpendicular to the direction of said optical axis;

a pattern board provided on said substrate stage and having a predetermined fiducial pattern;

an illuminating system for applying illuminating light of substantially the same wavelength as that of illuminating light for exposure from an underside of said pattern board to said fiducial pattern;

a photoelectric detector for receiving light created from said fiducial pattern and applied to a pattern surface of said mask through said projection optical system and reflected by said pattern surface and returned through said projection optical system and said fiducial pattern;

a measuring system for measuring position of a particular mark on said mask in a plane perpendicular to the optical axis of said projection optical system based on a detection signal output from said photoelectric detector when the light created from said fiducial pattern is applied to said particular mark; and

a detecting system for detecting a focus position at a predetermined point in a projection field of said projection optical system based on a detection signal output from said photoelectric detector when said pattern board and an imaging plane of said projection optical system are moved relative to each other in the direction of the optical axis of said projection optical system.

24. A projection exposure apparatus comprising:

a projection optical system for projecting a pattern on a mask onto a substrate;

a system for measuring a position or a positional deviation of a substrate surface along an optical axis of said projection optical system, at each of plural measuring points in a projection field of said projection optical system; and

a detecting system for weighting and averaging the measured positions or positional deviations so as to detect a single deviation between an imaging plane of said projection optical system and the substrate surface, along a direction of the optical axis.

25. An apparatus according to claim 24,

wherein said detecting system has a device for selecting at least two of the measured positions or positional deviations in accordance with a surface condition of said substrate, and a device for respectively weighting each of the selected positions or positional deviations, said detecting system performing processing to average the weighted positions or positional deviations.

26. An apparatus according to claim 24,

wherein said detecting system has a device for selecting at least two of the measured positions or positional deviations in accordance with a surface condition of said substrate, and a device for grouping each of the at least two of the measured positions or positional deviations and for respectively weighting average positions or positional deviations obtained by averaging a sum of the at least two of the measured positions or positional deviations with a number of data at each group, said detecting system performing processing to average the weighted positions or positional deviations.

27. An apparatus according to claim 24, further comprising:

a driving system for relatively moving the imaging plane of said projection optical system and said substrate along the direction of the optical axis in accordance with a detected single deviation so that the imaging plane and the substrate surface are substantially coincident with each other.

28. An apparatus according to claim 27,

wherein said driving system comprises a stage capable of holding said substrate and moving together therewith along the direction of the optical axis, and a member for driving said stage so that the imaging plane and the substrate surface are substantially coincident with each other.

29. An apparatus according to claim 24, further comprising:

a stage capable of holding said substrate and moving together therewith along the direction of the optical axis; and

a controller for controlling the stage to allow said substrate surface and said imaging plane to be matched in accordance with said single deviation.