Lithographic Apparatus and Device Manufacturing Method

• US 20070242246A1
• Filed: 04/10/2007
• Published: 10/18/2007
• Est. Priority Date: 12/22/2004
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: GUI, Cheng-Qun, Munnig Schmidt, Robert-Han, De Jager, Pieter
• Granted Patent: US 8,390,787 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• CPC Class Codes: G03F 7/70275 Multiple projection paths, e.g. array of projection systems, microlens projection systems or tandem projection systems
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70308 Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift

Abstract

A lithographic apparatus comprises an illumination system for supplying a beam of radiation, a patterning arrangement incorporating an array of individually controllable elements for imparting a pattern to the beam cross-section, a substrate table for supporting a substrate, and a projection system incorporating a microlens array for projecting the beam onto a target portion of the substrate. An error compensator is provided for supplying error correction values for compensating for the effect of positional errors in the microlens array, and a grey scale modulator is provided for supplying drive signals to controllable elements of the patterning arrangement in dependence on the error correction values in order to compensate for the effect of positional errors in the microlens array by varying the intensity of some parts of the pattern relative to other parts of the pattern.

Claims

1. An apparatus, comprising:

an illumination system that supplies a beam of radiation;

a patterning arrangement that patterns the beam;

a projection system that projects the patterned beam onto a target portion of a substrate; and

a grey scale modulator that supplies drive signals to the patterning arrangement to vary an intensity of respective parts of the patterned beam based on received error correction values, thereby compensating for errors in the projection system.

2. The apparatus according to claim 1, wherein:

the patterning arrangement comprises an array of individually controllable elements; and

the grey scale modulator is arranged to vary the intensity of radiation transmitted by at least some of the individually controllable elements of the array to compensate for the effect of errors in the projection system.

3. The apparatus according to claim 19, wherein the projection system comprises:

a micro lens array that produces image spots on the target portion of the substrate.

4. The apparatus according to claim 3, wherein the grey scale modulator corrects for positional errors of the micro lens array.

5. The apparatus according to claim 3, wherein the grey scale modulator corrects for magnification errors of the micro lens array.

6. The apparatus according to claim 3, wherein the error compensator comprises:

a sensor array that monitors errors in a positioning of the image spots of the micro lens array.

7. The apparatus according to claim 6, wherein the sensor array comprises a photodiode array.

8. The apparatus according to claim 3, wherein the error compensator determines an intensity correction matrix as a function of the positions of the image spots of the micro lens array and the errors in the positioning of the image spots.

9. The apparatus according to claim 1, wherein the patterning arrangement is disposed in an optical path of the beam of radiation between the illumination system and the substrate.

10. The apparatus according to claim 1, further comprising:

a scanning system that moves a substrate table supporting the substrate during projection of the patterned beam onto the target portion of the substrate.

11. The apparatus according to claim 10, wherein:

the patterning arrangement comprises an array of controllable elements arranged in parallel rows; and

the scanning system moves the substrate table in a scanning direction inclined to the rows.

19. The apparatus according to claim 1, further comprising an error compensator configured to supply the error correction values.

20. The apparatus according to claim 4, wherein the positional errors are substantially less than about 20 nm.

21. The apparatus according to claim 8, wherein the function further comprises at least one of:

(i) an error matrix;

(ii) a first grid pitch in a first direction;

(iii) a second grid pitch in a second direction;

(iv) a velocity of movement of the substrate relative to the micro lens array;

(v) a refresh rate of the patterning arrangement; and

(vi) an a tilt angle between rows of the micro lens array and a scanning direction.

12. A method, comprising:

patterning a beam of radiation using an adjustable patterning arrangement;

projecting the patterned beam of radiation onto a target portion of a substrate using a projection system;

detecting errors in the projection system; and

supplying drive signals to the patterning arrangement based on the detected errors to vary an intensity of respective portions of the patterned beam, thereby compensating for the effect of errors in the projection system.

13. The method according to claim 12, wherein:

the beam is patterned using an array of individually controllable elements; and

the intensity of radiation transmitted by at least some of the controllable elements of the array of individually controllable elements is varied in order to compensate for the effect of errors in the projection system.

14. The method according to claim 12, further comprising:

producing image spots on the target portion of the substrate using a micro lens array in the projection system.

15. The method according to claim 14, further comprising:

correcting positional errors in parts of the micro lens array.

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

correcting magnification errors in parts of the micro lens array.

17. The method according to claim 12, further comprising:

moving a substrate table supporting the substrate the projection of the beam onto the target portion of the substrate.

18. The method according to claim 17, wherein:

the patterning arrangement comprises an array of controllable elements arranged in parallel rows; and

the substrate table is moved in a scanning direction inclined to the rows during projection of the beam onto the target portion of the substrate.

22. The method according to claim 12, wherein varying the intensity of the respective portions of the patterned beam results in an overall uniform intensity of the patterned beam.

23. A method for calibrating a patterning device, comprising:

(a) measuring positioning errors of image spots;

(b) correcting the positioning errors by adjusting a grey level of a pair of adjacent spots in the image spots; and

(c) calibrating a nominal intensity of each of the image spots.

24. The method of claim 23, wherein step (b) further comprises:

determining the grey level to be applied to each of the adjacent spots based on a spot error lookup table.