Fingerprint sensing device comprising three-dimensional pattern

1. A fingerprint sensing device comprising:

a sensing chip comprising an array of sensing elements, said sensing elements being configured to be connected to readout circuitry for detecting a capacitive coupling between each of said sensing elements and a finger placed on a sensing surface of said sensing device;

a cover layer arranged vertically above said sensing elements to cover at least a portions of said sensing elements, wherein an outer surface of said cover layer form said sensing surface of said sensing device;

wherein said cover layer comprises a three-dimensional pattern configured to reduce an amount of reflected light within a predetermined sub-range of a visible range.

2. The sensing device according to claim 1 , wherein said three-dimensional pattern is a plasmonic array comprising a plurality of electrically conductive nanostructures, wherein said nanostructures are galvanically isolated from each other.

3. The sensing device according to claim 2 , wherein a size, shape and distribution of said nanostructures is selected to form a plasmonic array configured to reduce the amount of reflected light within a predetermined sub-range of the visible range.

4. The sensing device according to claim 1 , wherein said three-dimensional pattern is reflective diffraction grating.

5. The sensing device according to claim 1 , wherein said cover layer comprises a plurality of sub-layers.

6. The sensing device according to claim 5 , wherein said three-dimensional pattern is arranged in a first sub-layer which is covered by a second sub-layer.

7. The sensing device according to claim 1 , wherein said cover layer comprises a first area portion where said three-dimensional pattern is configured to reduce a first amount of reflected light within a first predetermined sub-range, and a second area portion where said three-dimensional pattern is configured to reduce a second amount of reflected light within a second predetermined sub-range, wherein said first predetermined sub-range is different from said second predetermined sub-range.

8. The sensing device according to claim 1 , wherein said three-dimensional pattern is arranged at said sensing surface, and wherein said pattern is configured to provide hydrophobic surface properties.

9. The sensing device according to claim 1 , wherein said three-dimensional pattern is configured to reduce the amount of reflected light within different predetermined sub-ranges of the visible range for different area portions of the sensing device such that an image is formed on said sensing surface.

10. The sensing device according to claim 1 , wherein said three-dimensional pattern is configured such that the predetermined sub-range is different for different viewing angles.

11. The sensing device according to claim 1 , wherein at least a portion of said cover layer is coated by an optically reflecting material.

12. The sensing device according to claim 1 , wherein at least protruding portions of said three-dimensional pattern are coated by an optically reflecting material.

13. A method for manufacturing a fingerprint sensing device, said method comprising:

providing a sensing chip comprising an array of sensing elements, said sensing elements being configured to be connected to readout circuitry for detecting a capacitive coupling between each of said sensing elements and a finger placed on a sensing surface of said sensing device;

forming a cover layer arranged vertically above said sensing elements to cover at least a portions of said sensing elements, wherein an outer surface of said cover layer form said sensing surface of said sensing device; and

in said cover layer, forming a three-dimensional pattern configured to reduce an amount of reflected light within a predetermined sub-range of a visible range.

14. The method according to claim 13 , wherein forming the three-dimensional pattern comprises nanoimprint lithography or photolithography.

15. The method according to claim 13 , further comprising depositing a reflective coating on protruding portions of said three-dimensional pattern.