Methods for producing a structured metal layer
View Patent ↗The invention provides methods which can be used to structure even precious metal electrodes with conventional CMP steps, in particular with the aid of conventional slurries such as are already used to structure non-precious metals. Owing to the formation of an alloy, the chemically active components of the slurry are capable of attacking the additive to the precious metal in the alloy, as a result of which the surface of the alloy layer is roughened and the mechanical removal of the precious metal is increased.
1. A method of producing a structured layer, which comprises the following steps:
providing a prestructured substrate;
applying to the prestructured substrate a precious metal and a donor material containing an additive which is not a precious metal in two or more layers;
subjecting the layers to heat treatment at a temperature of between approximately 400° C. and approximately 800° C., such that the additive diffuses into the precious metal and an alloy layer is produced; and
polishing the alloy layer by chemical and mechanical means.
2. The method according to claim 1 , wherein the donor material essentially comprises only the additive.
3. The method according to claim 1 , which comprises applying the donor material to the substrate before the precious metal.
4. The method according to claim 3 , which comprises alternately applying several layers of the donor material and at least one layer of the precious metal, starting with a layer of the donor material.
5. The method according to claim 1 , wherein the precious metal is applied to the substrate before the donor material.
6. The method according to claim 1 , wherein several layers of the precious metal and at least one layer of the donor material are applied alternately, starting with a layer of the precious metal.
7. The method according to claim 1 , wherein the thickness of the donor material is selected such that during heat treatment the donor material essentially diffuses completely into the precious metal.
8. The method according to claim 1 , wherein the precious metal is an element from Group 8b of the Periodic Table of the Elements and/or is Au.
9. The method according to claim 8 , wherein the precious metal is from Group 8b of the Periodic Table of the Elements and/or is Ir.
10. The method according to claim 1 , wherein the additive is Ti, TiO x , Ta, W, Bi, Ru and/or Pd.
11. The method according to claim 1 , wherein the donor material is Ti, TiO x , TiN, Ta, TaN, W, WN, Bi, BiO x , IrO x , IrHfO x , RuO x and/or PdO x .
12. The method according to claim 1 , wherein the alloy layer produced contains between approximately 5 and approximately 30 atom % of the donor material.
13. The method according to claim 1 , wherein a slurry containing water, abrasive particles and at least one oxidant is used for the chemical mechanical polishing.
14. The method according to claim 13 , wherein Al 2 O 3 particles or SiO 2 particles are used as abrasive particles.
15. The method according to claim 13 , wherein the abrasive particles have a size of approximately 50 to 300 nm.
16. The method according to claim 13 , wherein H 2 O 2 is used as the at least one oxidant.
17. The method according to claim 13 , wherein the slurry has at least one stabilizer.
18. The method according to claim 17 , wherein the stabilizer is polyacrylic acid.