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1. (WO2017036729) METHOD FOR FABRICATING HIGH ASPECT RATIO GRATINGS FOR PHASE CONTRAST IMAGING
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Patent Claims

1. A method for fabricating high aspect ratio gratings, comprising :

- providing a substrate and a patterned metal catalyst film disposed on said substrate;

forming an interconnected structure within the patterned metal catalyst film by heating the substrate at temperature between 100 °C and the melting

temperature of the substrate;

etching the substrate by an etchant solution containing a fluoride etchant and an oxidizing agent, thereby controlling the metal catalyst movement during metal assisted chemical etching of high aspect ratio structures.

2. The method according to claim 1, wherein said heating comprises using a process selected from the group consisting of thermal annealing, laser annealing, rapid thermal

annealing, furnace, flash annealing, electron beam

irradiation, ion beam irradiation, exposure to plasma.

3. The method according to claim 1 or 2, wherein the said metal is selected from the group of gold, silver, platinum and tungsten, wherein the said substrate comprises a material selected from the group consisting of silicon, GaAs, InP, GaP, GaN, and III-V semiconductors and any compounds or alloys of these materials.

4. A method for fabricating high aspect ratio gratings, comprising :

a) providing a high aspect ratio recess structure;

b) generating an electrical insulation on the high aspect ratio recess structure by thermal oxidation, plasma enhanced oxidation, coating a dielectric layer by PECVD or ALD

dielectric layer or any combination of these techniques; c) depositing by shadow deposition of material with high etching resistance on top of the electrical insulation and, partly, on sidewalls of high aspect ratio recess structure; d) etching the insulation layer at the bottom of the recess structure through a high etching resistance mask; and

e) seedless electroplating into the high aspect ratio recess structure .

5. A method of claim 4, wherein the electroplated metal is selected from a group of gold, nickel, copper, wherein the said substrate comprises of a material selected from the group consisting of silicon, GaAs, InP, GaP, GaN, and III-V

semiconductors and any compounds or alloys of these materials.

6. A method for fabricating high aspect ratio gratings, comprising the step of:

a) forming a high aspect ratio recess structure by deep reactive ion etching, anisotropic wet-etching, metal assisted chemical etching or photo-assisted chemical etching;

b) coating the recess structure by a conductive layer by atomic layer deposition;

c) coating the recess structure by an insulating layer by atomic layer deposition or PECVD;

d) shadow deposition of material with high etching resistance on top and, partly, on sidewalls of high aspect ratio recess structure by thermal evaporation or PECVD;

e) etching the insulation layer at the bottom of the recess structure through a high etching resistance mask;

f) filling the high aspect ratio recess structure by

electroplating.

7. The method of claim 6, wherein the electroplated metal is selected from a group of gold, nickel, copper, wherein the said substrate comprises of a material selected from the group consisting of silicon, GaAs, InP, GaP, GaN, and III-V

semiconductors and any compounds or alloys of these materials.

8. The method of claim 6 or 7, wherein the conductive layer is selected from a group of I r , Pd, Pt , Ru , W wherein the

insulating layer is selected from a group of S 1 O2 , AI2O3, T 1 O2 , CaO, CuO, Er203 , Ga203 , Hf O2 , La20s , MgO, NID2O5 , SC2O3 , a20s ,

VXOY, Y2O3, Yb203 , ZnO, Z r02 .

9. A method for fabricating high aspect ratio gratings, comprising :

a) forming a high aspect ratio recess structure by deep reactive ion etching, anisotropic wet-etching, metal assisted chemical etching or photo-assisted chemical etching; and b) casting of metal into recess structure.

10. The method of claim 9, wherein the electroplated metal is selected from a group of gold, nickel, copper, wherein the said substrate comprises of a material selected from the group consisting of Si, GaAs, InP, GaP, GaN, and III-V

semiconductors and any compounds or alloys of these materials.

11. The method of claim 9 or 10, wherein the casting material is selected from a group consisting of Au, Sn, Au2 o S ns o , Au-Sn alloy, Au-Si alloy.

12. A method for fabricating high aspect ratio gratings, comprising:

a) forming a high aspect ratio recess structure by deep reactive ion etching, anisotropic wet-etching, metal assisted chemical etching or photo-assisted chemical etching;

b) pre-filling the recess structure by electroplating;

c) melting the electroplated metal into the high aspect ratio recess structure to prevent voids in electroplated layer.

13. The method of claim 12, wherein the electroplated metal is gold or copper, wherein the said substrate comprises of a material selected from the group consisting of silicon, GaAs, InP, GaP, GaN, III-V semiconductors and any compounds or alloys of these materials.

14. A method for fabricating high aspect ratio gratings, comprising :

a) forming high aspect ratio recess structure by deep reactive ion etching, anisotropic wet-etching, metal assisted chemical etching or photo-assisted chemical etching;

b) pre-coating of the recess structure by a material with good wetting characteristic;

c) casting of metal with low melting temperature into the high aspect ratio recess structure.

15. The method of claim 14, wherein the said substrate

comprises of a material selected from the group consisting of Si, GaAs, InP, GaP, GaN, and III-V semiconductors or any compounds or alloys of these materials, wherein the

electroplated metal is gold wherein the casting material selected from the group consisting of Au, Sn, Au2oSnso, Au-Sn alloy, Au-Si alloy.

16. A method for fabricating high aspect ratio gratings, comprising:

a) providing a bonded wafer comprising a carrier wafer, a metal layer and a device wafer;

b) forming a high aspect ratio recess structure in the device layer by deep reactive ion etching, anisotropic wet-etching, metal assisted chemical etching or photo-assisted chemical etching;

c) electroplating into high aspect ratio recess structure.

17. The method of claim 16, wherein carrier and device wafer consist of silicon, GaAs, InP, GaP, GaN, and III-V

semiconductors or any compounds or alloys of these materials, wherein the metal layer is selected from a group consisting of Cu, Cr, Au, Ni, Al or combination of these materials.

18. The method of claim 16 or 17, wherein the support wafer is removed by chemical etching of the metal layer between the wafers .

19. A method for fabricating high aspect ratio gratings;

comprising :

a) providing a bonded wafer comprising a carrier wafer, a sacrificial layer, a metal layer and device wafer;

b) forming a high aspect ratio recess structure in the device layer by deep reactive ion etching, anisotropic wet-etching, metal assisted chemical etching or photo-assisted chemical etching; electroplating into high aspect ratio recess

structure; and

c) removal of the carrier wafer through the chemical

dissolving or thermal treatment of the sacrificial layer.

20. A method to fabricate the absorbing grating on bended substrates; comprising the following steps:

a) forming a high aspect ratio recess structure;

b) bending the substrate to an angle corresponding to

divergence of the beam and geometry of a setup to be used; c) filling the high aspect ratio recess structure with metal.

21. A method to produce gratings for x-ray or neutron phase contrast imaging, whereas the patterning of the gratings is performed using displacement Talbot lithography.

22. A method to produce gratings for x-ray imaging, where the high aspect ratio recess structure is filled by atomic layer deposited metal from a group of Ir, Pd, Pt, Ru, W .

23. A method to produce gratings for neutron imaging, where the high aspect ratio recess structure is filled by atomic layer deposited gadolinium, gadolinium oxide or other

gadolinium containing compound material.