Method and system for printing high-resolution periodic patterns

1. A method of printing a desired pattern of periodic features, the method which comprises:

providing a mask bearing a mask pattern of periodic features having an array type and a period;

providing a substrate bearing a photosensitive layer;

arranging the substrate substantially parallel to and with a separation from the mask;

generating substantially collimated light with a wavelength and an intensity, wherein at least the wavelength is temporally variable to deliver a spectral distribution of energy density;

illuminating the mask pattern with the light while varying at least the wavelength thereof so as to deliver a spectral distribution of energy density, such that a light-field transmitted by the mask is instantaneously composed of a range of transversal intensity distributions between Talbot planes, and wherein the photosensitive layer is exposed to a time-integrated intensity distribution printing the desired pattern;

wherein the separation and the spectral distribution are configured in relation to the period and array type so that the time-integrated intensity distribution corresponds substantially to an average of the range of transversal intensity distributions.

2. The method according to claim 1 , which comprises varying the wavelength at a constant rate or a variable rate during the step of illuminating the mask pattern.

3. The method according to claim 1 , wherein the spectral distribution of energy density is substantially flat with a spectral range such that varying the wavelength across the range causes the transversal intensity distribution illuminating the photoresist to longitudinally displace by a distance that corresponds substantially to the Talbot period, or an integer multiple thereof, of the transmitted light-field produced by light at the central wavelength of the range.

4. The method according to claim 1 , wherein the spectral distribution of energy density corresponds substantially to one of a Gaussian, triangular and truncated cosine profile, and a full-width half-maximum spectral range of the profile is such that varying the wavelength across the range causes the transversal intensity distribution illuminating the photoresist to longitudinally displace by a distance that corresponds substantially to at least the Talbot period of the transmitted light-field produced by light at the central wavelength of the range.

5. The method according to claim 1 , which comprises continuously varying the wavelength during the illuminating step.

6. The method according to claim 1 , which comprises varying the wavelength in steps during the illuminating step.

7. The method according to claim 1 , wherein the array type is selected from the group consisting of a linear grating, a hexagonal array, a square array and a rectangular array.

8. The method according to claim 1 , which comprises varying the wavelength once or a plurality of times over a range of wavelengths during the illuminating step.

9. The method according to claim 1 , wherein the periodic features of both the desired pattern and mask pattern are exactly periodic or are quasi-periodic.

10. The method according to claim 1 , wherein the desired pattern of periodic features comprises a plurality of sub-patterns with different periods, the mask pattern comprises a plurality of sub-patterns with different periods, wherein each sub-pattern generates a light-field composed of Talbot planes separated by a Talbot distance, and wherein the tilt angle and the intensity envelope are arranged in relation to the Talbot distance of the light-field from the sub-pattern with a largest period.

11. The method according to claim 1 , which further comprises introducing a fluid between the mask and substrate.

12. The method according to claim 1 , wherein features of the mask pattern are formed in at least one of a layer of an opaque material and a layer of a phase shifting material, and on a transparent substrate.

13. An apparatus for printing a desired pattern of periodic features, the apparatus comprising:

a mask bearing a mask pattern of periodic features having an array type and a period;

a substrate bearing a photosensitive layer;

a device for arranging the substrate substantially parallel to and with a separation from the mask;

a generating and varying device for generating substantially collimated light with a wavelength and an intensity and for temporally varying at least the wavelength in order to deliver a spectral distribution of energy density;

an illumination device for illuminating the mask pattern with the light while varying at least the wavelength thereof so as to deliver a spectral distribution of energy density, such that a light-field transmitted by the mask is instantaneously composed of a range of transversal intensity distributions between Talbot planes, and wherein said photosensitive layer is exposed to a time-integrated intensity distribution printing the desired pattern;

wherein the separation and spectral distribution are arranged in relation to the period and array type so that the time-integrated intensity distribution corresponds substantially to an average of a range of transversal intensity distributions.

14. The apparatus according to claim 13 , wherein said generating and varying device is configured to produce a spectral distribution of energy density that is substantially flat.

15. The apparatus according to claim 13 , wherein said generating and varying device is configured to produce a spectral distribution of energy density that corresponds substantially to a Gaussian, triangular or truncated cosine profile.

16. The apparatus according to claim 13 , wherein said illumination device is a light-generating and wavelength-varying means including an optical parametric oscillator.

17. The apparatus according to claim 13 , wherein said intensity varying device is a variable attenuator.