Method for producing a medical functional element comprising a selfsupporting lattice structure

1. A method for producing a medical functional element, the method comprising:

applying a first layer to a substrate layer;

etching the first layer to form a lattice structured first layer;

undercutting the structured first layer using a wet chemical etching process acting on the substrate layer and forming a catch basin in the substrate layer;

applying a web constructional layer having substantially perpendicular walls to the first layer; and

removing the substrate layer in order to form a self-supporting lattice structure having interconnected webs;

wherein during the step of applying the web constructional layer, scrap material is formed in the catch basin and forms an overlap area with the web constructional layer;

wherein the first layer forms a web attachment layer, which has a smaller layer thickness than the web constructional layer and is intimately bonded to the web constructional layer in such a way that the web attachment layer, together with the web constructional layer, forms the webs of the self-supporting lattice structure.

2. The method as claimed in claim 1 , wherein the web attachment layer has the same material as the web constructional layer.

3. The method as claimed in claim 1 , wherein in the etching step the web attachment layer is structured by a wet chemical etching process.

4. The method as claimed in claim 1 , wherein the scrap material is formed such that it contacts and provides lateral support to the web attachment layer.

5. The method as claimed in claim 4 , wherein the catch basin has an etching depth that is smaller than the layer thickness of the scrap material and/or of the web constructional layer.

6. The method as claimed in claim 5 , wherein the ratio between etching depth and the layer thickness of the web constructional layer is less than 1:1.

7. The method as claimed in claim 1 , wherein the web attachment layer and/or the web constructional layer are formed by a physical deposition process.

8. The method as claimed in claim 1 , further comprising applying at least one further web-forming layer to the web constructional layer.

9. The method as claimed in claim 8 , wherein the further web-forming layer has a material different from the web constructional layer.

10. The method as claimed in claim 8 , wherein the further web-forming layer comprises a bioabsorbable or X-ray-visible material.

11. The method as claimed in claim 1 , wherein the web attachment layer and the web constructional layer comprise a nickel-titanium alloy.

12. The method as claimed in claim 1 , further comprising prior to etching, coating the web attachment layer with a photoactive layer, and subjecting the photoactive layer to a lithographic process to form an etching mask in the shape of the lattice structure that is to be produced.

13. The method as claimed in claim 5 , wherein the ratio between etching depth and the layer thickness of the web constructional layer is less than 1:2.

14. The method as claimed in claim 5 , wherein the ratio between etching depth and the layer thickness of the web constructional layer is less than 1:4.

15. The method as claimed in claim 5 , wherein the ratio between etching depth and the layer thickness of the web constructional layer is less than 1:10.

16. The method as claimed in claim 1 , wherein the web attachment layer and/or the web constructional layer are formed by a sputtering process.

17. The method as claimed in claim 8 , wherein the further web-forming layer comprises tantalum.