Inspection apparatus, inspection method, exposure method, and method for manufacturing semiconductor device
A surface inspection apparatus ( 1 ) has a stage ( 5 ) for supporting a wafer ( 10 ) on which predetermined patterns have been formed by exposure using an exposure device ( 100 ); an illumination system ( 20 ) for irradiating an illuminating light on the surface of the wafer ( 10 ) supported by the stage ( 5 ); an imaging device ( 35 ) for detecting light from the surface of the wafer ( 10 ) on which illuminating light has been irradiated, and outputting a detection signal; and an image processing unit ( 40 ) for determining the focus state during exposure, on the basis of the detection signal sent from the imaging device ( 35 ).
1. An inspection apparatus comprising:
an illumination unit for irradiating an illuminating light on a plurality of patterns which are formed on a substrate together or on a plurality of substrates separately, which were made by exposure, the patterns comprising a first set of patterns and a second set of patterns, wherein the first set of patterns and the second set of patterns are irradiated separately or together;
a detection unit for detecting light from the patterns on which the illuminating light has been irradiated;
a computation unit for determining an exposure state of an exposure device when the patterns were made, the exposure state comprising an exposure amount and a focus state, wherein:
the computation unit:
determines a first relationship between:
a plurality of different exposure states and detected results of the light from the first set of patterns made under the plurality of different exposure states,
determines a second relationship between:
a plurality of different exposure states and detected results of the light from the second set of patterns made under the plurality of different exposure states,
compares the exposure states and detected results of the first relationship and the exposure states and detected results of the second relationship; and
determines the exposure state of the exposure device in effect when the first set of patterns or the second set of patterns were exposed, on the basis of a result compared between the exposure states and detected results of the first relationship and the exposure states and detected results of the second relationship; and
an output unit for outputting the exposure state determined by the computation unit to at least one of the exposure device and a computer which is communicably connected to the exposure device, wherein
the computer outputs the exposure state determined by the computation unit to the exposure device to set the exposure state of the exposure device,
the focus state of the exposure device is determined by setting, based on the exposure state determined by the computation unit, a relative location between a pattern image to be exposed and a substrate, and
the exposure amount is determined by setting, based on the exposure state determined by the computation unit, an exposure light intensity or an exposure time period.
2. The inspection apparatus according to claim 1 , wherein the computation unit computes as the exposure state at least one of an exposure amount and a focus state in effect when the patterns were exposed.
3. The inspection apparatus according to claim 2 , further comprising
a controller for controlling the illumination unit and the detection unit, the controller controlling at least one of the illumination unit and the detection unit so that:
a change of at least one of the first and second relationships due to an offset of the focus state in effect is smaller than that due to an offset of the exposure amount; or
a change of at least one of the first and second relationships due to an offset of the exposure amount is smaller than that due to an offset of the focus state in effect.
4. The inspection apparatus according to claim 1 , 2 , or 3 , wherein the detection unit detects diffracted light from the patterns.
5. The inspection apparatus according to claim 4 , wherein the detection unit detects diffracted light of a fourth order or greater.
6. The inspection apparatus according to claim 1 , 2 , or 3 , wherein the detection unit detects a predetermined polarized light component in light reflected from the patterns.
7. The inspection apparatus according to claim 1 , wherein the detection unit detects light from the patterns over a plurality of times, and the computation unit determines the exposure state on the basis of an integral signal obtained by integrating the results of the plurality of detections.
8. The inspection apparatus according to claim 1 , wherein the illumination unit illuminates in a lump, using substantially collimated light, an entire surface on which the plurality of patterns were formed; and
the detection unit detects in a lump the light from the plurality of patterns on the surface.
9. The inspection apparatus according to claim 1 , further comprising an output unit for outputting the exposure state determined by the computation unit, the exposure state being sent so as to be capable of being fed back to an exposure device that performed the exposure.
10. An inspection method comprising the steps of:
irradiating an illuminating light on a plurality of patterns which are formed on a substrate together or on a plurality of substrates separately, which were made by exposure, the patterns comprising a first set of patterns and a second set of patterns, wherein the first set of patterns and the second set of patterns are irradiated separately or together;
detecting light from the patterns on which the illuminating light has been irradiated; and
determining an exposure state of an exposure device when the patterns were made, the exposure state comprising an exposure amount and a focus state, wherein the determining step comprises:
determining a first relationship between:
a plurality of different exposure states; and
detected results of the light from the first set of patterns made under the plurality of different exposure states,
determining a second relationship between:
a plurality of different exposure states; and
detected results of the light from the second set of patterns made under the plurality of different exposure states;
comparing the exposure states and detected results of the first relationship and the exposure states and detected results of the second relationship;
determining the exposure state of the exposure device in effect when the plurality of patterns were exposed, on the basis of a result compared between the exposure states and detected results of the first relationship and the exposure states and detected results of the second relationship; and
outputting the determined exposure state to at least one of the exposure device and a computer which is communicably connected to the exposure device, wherein
the computer outputs the exposure state determined by the computation unit to the exposure device to set the exposure state of the exposure device,
the focus state of the exposure device is determined by setting, based on the exposure state determined by the computation unit, a relative location between a pattern image to be exposed and a substrate, and
the exposure amount is determined by setting, based on the exposure state determined by the computation unit, an exposure light intensity or an exposure time period.
11. The inspection method according to claim 10 , wherein at least one of an exposure amount and a focus state in effect when the patterns were exposed is determined as the exposure state.
12. The inspection method according to claim 11 , wherein at least one of an illumination unit configured to illuminate and a detection unit configured to detect results are controlled so that a change of at least one of the first and second relationships due to an offset of the focus state in effect is smaller than that due to an offset of the exposure amount, or a change of at least one of the first and second relationships due to an offset of the exposure amount is smaller than that due to an offset of the focus state in effect.
13. The inspection method according to claim 10 , 11 , or 12 , wherein diffracted light from the patterns is detected.
14. The inspection method according to claim 10 , 11 , or 12 , wherein a predetermined polarized light component of light from the patterns is detected.
15. The inspection method according to claim 10 , wherein light from the patterns is detected over a plurality of times, and the exposure state is determined on the basis of an integral signal obtained by integrating the results of the plurality of detections.
16. The inspection method according to claim 10 , wherein an entire surface on which the patterns were formed is illuminated in a lump, and the light from the patterns on the entire surface is detected in a lump.
17. The inspection apparatus according to claim 1 , wherein the computation unit determines the exposure state when the second set of patterns were made based on the comparison.
18. The inspection apparatus according to claim 1 , wherein the first and second relationships are respectively represented by first and second functions, and the comparison is made by comparing the functions.
19. The inspection apparatus according to claim 18 , wherein the comparison is made by determining the correlation in shifting the first function to or from the second function.
20. The inspection apparatus according to claim 18 , wherein the comparison of the functions is made at the exposure state when the detected result by the detection unit becomes maximum.
21. The inspection apparatus according to claim 18 , 19 , or 20 , wherein the functions are polynomials of a fourth order or higher.
22. The inspection method according to claim 13 , wherein diffracted light of a fourth order or greater is detected.
23. The inspection method according to claim 10 , wherein the exposure state is determined when the second set of patterns were made based on the comparison.
24. The inspection method according to claim 10 , wherein the first and second relationships are respectively represented by first and second functions, and the comparison is made by comparing the functions.
25. The inspection method according to claim 24 , wherein the comparison is made by determining the correlation in shifting the first function to or from the second function.
26. The inspection method according to claim 24 , wherein the comparison of the functions is made at the exposure state when the detected result becomes maximum.
27. The inspection method according to claim 24 , 25 , or 26 , wherein the functions are polynomials of a fourth order or higher.
28. The inspection apparatus according to claim 1 , wherein the plurality of patterns are on a substrate.
29. The inspection apparatus according to claim 28 , further comprising
a modification unit for modifying at least one of the relative position between the substrate and the detection unit and the relative position between the substrate and the illumination unit, wherein:
the detection unit detects results of light from the plurality of patterns before and after modification of the relative position; and
the computation unit determines the exposure state when the second set of patterns were exposed, on the basis of the detected results before and after modification of the relative position.
30. The inspection apparatus according to claim 29 , wherein the computation unit determines the exposure state on the basis of the average of the detected results for a plurality of the relative positions.
31. The inspection method according to claim 10 , wherein the plurality of patterns are on a substrate.
32. The inspection method according to claim 31 , further comprising:
modifying at least one of the relative position between the substrate and a detection unit configured to detect results and the relative position between the substrate and an illumination unit configured to illuminate,
detecting results of light from the plurality of patterns before and after modification of the relative position by the detection unit; and
determining the exposure state when the second set of patterns were exposed on the basis of the detected results produced before and after modification of the relative position.
33. The inspection method according to claim 32 , wherein the exposure state is determined on the basis of the average of the detected results produced for a plurality of the relative positions.