PIXEL

1 . A pixel, comprising:

a silicon portion having a first face configured to received light;

first trenches penetrating into the silicon portion from the first face, wherein said first trenches extend parallel to a first direction and are regularly spaced in a second direction perpendicular to the first direction; and

second trenches penetrating into the silicon portion from the first face, wherein the second trenches extend parallel to the second direction and are regularly spaced in the first direction; and

in a central region of the first face:

the first trenches include first notches penetrating into the silicon from the first face, wherein each first notch extends from a first trench toward a neighboring first trench without reaching said neighboring first trench, and wherein each first notch is aligned with a corresponding second trench.

2 . The pixel according to claim 1 , wherein in said central region of the first face;

the second trenches include second notches penetrating into the silicon from the first face, wherein each second notch extends from a second trench toward a neighboring second trench without reaching said neighboring second trench, and wherein each second notch is aligned with a corresponding first trench.

3 . The pixel according to claim 2 , wherein the first face has two first sides parallel to the first direction and two second sides parallel to the second direction.

4 . The pixel according to claim 3 , wherein the first face comprises:

a first region extending from a first one of the first sides toward the central region, the first region comprising only second trenches;

a second region extending from a second one of the first sides toward the central region, the second region comprising only second trenches;

a third region extending from a first one of the second sides toward the central region, the third region comprising only first trenches;

a fourth region extending from a second one of the second sides toward the central region, the fourth region comprising only first trenches.

5 . The pixel according to claim 4 , wherein there are no notches on the first trenches in the first and third regions.

6 . The pixel according to claim 4 , wherein there are no notches on the second trenches in the second and fourth regions.

7 . The pixel according to claim 3 , further comprising at least one V-shaped pattern made of one first trench connected to one second trench, wherein the at least one V-shaped pattern is arranged in a corner of the first face, outside the central region.

8 . The pixel according to claim 7 , wherein, in the corner of the first face, said at least one V-shaped pattern arranged symmetrical with respect to a diagonal of the first face extending from said corner, and wherein the at least one V-shaped pattern has an apex turned toward the center of the first face.

9 . The pixel according to claim 3 , further comprising a plurality of V-shaped patterns, each V-shaped pattern made of one first trench, wherein the plurality of V-shaped patterns are arranged in a corner of the first face, outside the central region.

10 . The pixel according to claim 9 , wherein the plurality of V-shaped patterns are successively and regularly arranged from said corner toward the center of the first face, each of said V-shaped patterns having an apex turned toward the center of the first face, each of said V-shaped patterns being symmetrical with respect to a diagonal extending from said corner.

11 . The pixel according to claim 10 , wherein the first trenches of the plurality of V-shaped patterns comprise first notches in the central region and/or wherein the second trenches of the plurality of V-shaped patterns comprise second notches in the central region.

12 . The pixel according to claim 3 , wherein, in the first direction, the central region has a length comprised between 50 and 70% of the length of each first side, and, in the second direction, the central region has a length comprised between 50 and 70% of the length of each first side.

13 . The pixel according to claim 2 , wherein, in the central region, the first trenches are aligned on first lines of a grid pattern and the second trenches are aligned on second lines of a grid pattern, the first notches being aligned on the second lines of the grid pattern and the second notches being aligned with the first lines.

14 . The pixel according to claim 2 , wherein, in the central region, the first and second trenches together with the first and second notches form a grid-like pattern.

15 . The pixel according to claim 2 , wherein the first and second trenches together with the first and second notches form a pattern having a 900 rotational symmetry with respect to the center of the first face.

16 . The pixel according to claim 2 , wherein the first trenches are disposed with a first pitch in the second direction and the second trenches are disposed with a second pitch in the first direction, the first and second pitches being equal to each other and comprised between 300 and 600 nm.

17 . The pixel according to claim 15 , wherein the length of the first notches in the second direction and the length of the second notches in the first direction are comprised between 40 and 60% of the first and second pitches.

18 . The pixel according to claim 1 , wherein a width of the first trenches is equal to a width of the second trenches, the width of the first and second trenches being comprised between 150 and 250 nm.

19 . The pixel according to claim 1 , wherein the light is infra-red light.

20 . A method of fabricating the pixel according to claim 2 , comprising:

forming a hard mask on the first face of the pixel;

forming a photoresist mask on the hard mask;

patterning the photoresist mask in order to form therein a first opening exposing the hard mask at each location of a first trench, each location of a second trench, each location of a first notch and each location of a second notch;

etching, through said first openings, second openings in the hard mask; and

etching, through said second openings, the first and second trenches and the first and second notches in the silicon portion.