Electrical device and a method for forming an electrical device

1. An electrical device comprising:

a redistribution layer structure;

an inter-diffusing material contact structure; and

a vertical electrically conductive structure located between the redistribution layer structure and the inter-diffusing material contact structure,

wherein the vertical electrically conductive structure comprises a diffusion barrier structure located adjacently to the inter-diffusing material contact structure,

wherein the diffusion barrier structure and the redistribution layer structure comprise different lateral dimensions.

2. The electrical device according to claim 1 , wherein the redistribution layer structure comprises a low-ohmic redistribution layer comprising mainly copper or silver.

3. The electrical device according to claim 1 , wherein the inter-diffusing material contact structure comprises a material with a melting temperature of less than 400° C. in contact with the diffusion barrier structure.

4. The electrical device according to claim 1 , wherein the inter-diffusing material contact structure comprises a tin-based alloy or an indium based alloy in contact with the diffusion barrier structure.

5. The electrical device according to claim 1 , wherein the diffusion barrier structure comprises a thickness of more than 500 nm.

6. The electrical device according to claim 1 , wherein the diffusion barrier structure comprises at least one diffusion barrier layer and one copper or silver layer.

7. The electrical device according to claim 6 , wherein the copper or silver layer of the diffusion barrier structure comprises a thickness of less than 500 nm.

8. The electrical device according to claim 6 , wherein the at least one diffusion barrier layer of the diffusion barrier structure is a titanium-tungsten layer.

9. The electrical device according to claim 6 , wherein the diffusion barrier structure comprises a layer stack of alternating diffusion barrier layers and copper or silver layers.

10. The electrical device according to claim 6 , wherein a volume of copper or silver of a lowermost copper or silver layer of the diffusion barrier structure located between a lowermost diffusion barrier layer and an opposite diffusion barrier layer is less than 1*10 −4 cm 3 per cm 2 .

11. The electrical device according to claim 1 , wherein the diffusion barrier structure comprises a nickel based layer.

12. The electrical device according to claim 1 , wherein the redistribution layer structure comprises a diffusion barrier layer and a low-ohmic redistribution layer.

13. The electrical device according to claim 12 , wherein the diffusion barrier structure is arranged between the diffusion barrier layer of the redistribution layer structure and the inter-diffusing material contact structure to avoid a direct interface between the diffusion barrier layer of the redistribution layer structure and the inter-diffusing material contact structure.

14. The electrical device according to claim 12 , wherein the diffusion barrier layer and the low-ohmic redistribution layer of the redistribution layer structure comprise equal lateral dimensions.

15. The electrical device according to claim 1 , wherein the diffusion barrier structure is structured independent from the redistribution layer structure to implement the different lateral dimensions of the diffusion barrier structure and the redistribution layer structure.

16. The electrical device according to claim 1 , wherein a surface roughness of a surface of the inter-diffusing material contact structure located adjacently to the diffusion barrier structure is higher than a surface roughness of a surface of the diffusion barrier structure located adjacently to the redistribution layer structure.

17. The electrical device according to claim 1 , wherein an upper part of the vertical electrically conductive structure is formed by a vertical extension of the redistribution layer structure.

18. The electrical device according to claim 17 , wherein a lateral dimension of the diffusion barrier structure is larger than a lateral dimension of the upper part of the vertical electrically conductive structure.

19. The electrical device according to claim 17 , wherein an outside portion of a footprint of the upper part of the vertical electrically conductive structure is located outside of a footprint of the diffusion barrier structure and outside a footprint of the inter-diffusing material contact structure.

20. The electrical device according to claim 1 , wherein the diffusion barrier structure laterally covers the whole inter-diffusing material contact structure.

21. The electrical device according to claim 1 , further comprising a second contact structure comprising a material different from a material of the inter-diffusing material contact structure, wherein a vertical extension of the redistribution layer structure is in contact with the second contact structure.

22. The electrical device according to claim 21 , wherein the second contact structure comprises aluminum at a surface in contact with the vertical extension of the redistribution layer structure.

23. A method for forming an electrical device, the method comprising:

forming a diffusion barrier structure adjacently to an inter-diffusing material contact structure based on a first structuring process; and

forming a redistribution layer structure in contact with the diffusion barrier structure based on a second structuring process independent from the first structuring process and after the first structuring process, wherein the diffusion barrier structure and the redistribution layer structure comprise different lateral dimensions structured by the two independent structuring processes.

24. The electrical device according to claim 23 , wherein forming the diffusion barrier structure comprises forming at least one diffusion barrier layer and forming at least one copper or silver layer.

25. The electrical device according to claim 23 , wherein forming the diffusion barrier structure comprises forming a nickel based layer.