One-piece, hollow micromechanical part with several functional levels formed of a synthetic carbon allotrope based material

1. A method for fabrication of a one-piece micromechanical part made of a synthetic carbon allotrope based material, the method comprising:

a) forming a substrate, the substrate including, on at least three levels, a negative cavity for the one-piece micromechanical part to be fabricated;

b) coating the negative cavity of the substrate with a layer of the synthetic carbon allotrope based material in a smaller thickness than a depth of each of the at least three levels of the negative cavity; and

c) removing the substrate to release the one-piece micromechanical part formed in the negative cavity,

wherein a) comprises:

i) forming a first wafer including at least a first pattern etched through;

ii) forming a second wafer including at least a second pattern etched through;

iii) forming a third wafer with no through pattern; and

iv) bonding the first, second, and third wafers to form the substrate including the negative cavity on the at least three levels.

2. The method according to claim 1 , wherein, the second wafer is formed by including the second pattern etched through and a third etched non-through pattern communicating with the second pattern.

3. The method according to claim 1 , wherein, the third wafer is formed by including an etched non-through pattern.

4. The method according to claim 1 , wherein b) comprises:

b1) forming a sacrificial layer on one portion of the substrate;

b2) depositing particles on the substrate intended to form nucleation sites;

b3) removing the sacrificial layer to selectively leave one portion of the substrate free of any particles; and

b4) chemical vapor phase depositing the layer of the synthetic carbon allotrope based material so that the layer is deposited only where particles remain.

5. The method according to claim 1 , wherein b) comprises:

b5) forming a sacrificial layer on one portion of the substrate;

b6) chemical vapor phase depositing the layer of the synthetic carbon allotrope based material on the substrate; and

b7) removing the sacrificial layer to selectively leave one portion of the substrate free of any layer.

6. The method according to claim 1 , wherein at least one of the at least three levels of the negative cavity includes a wall forming a toothing.

7. The method according to claim 1 , wherein the synthetic carbon allotrope based material is in crystallized form.

8. The method according to claim 1 , wherein the synthetic carbon allotrope based material is in amorphous form.

9. The method according to claim 1 , wherein after b), the method further comprises:

d) removing from the substrate a greater thickness than that of the layer deposited in b), to leave the layer deposited in b) only in the negative cavity.

10. The method according to claim 1 , wherein prior to c), the method further comprises:

e) filling the negative cavity, coated with the synthetic carbon allotrope based material, with a second material so that, after c), obtaining the one-piece micromechanical part formed of the synthetic carbon allotrope based material strengthened by and/or decorated with the second material.

11. The method according to claim 10 , wherein, in e), the second material is formed projecting from the negative cavity to form an additional functional level of the one-piece micromechanical part.

12. The method according to claim 10 , wherein the second material includes a metal or metal alloy.