Method of coating surface of substrate hole with layer of reduced graphene oxide
A method for coating a layer of reduced graphene oxide (rGO) on the surface of substrate holes (especially holes with high aspect ratio) includes a serial wet process steps of hydrophilic treatment of the surface of the substrate, self-assembly of a silane layer, steps of grafting of a polymer layer, grafting of graphene oxide (GO), intercalation of metal ions, and intercalation of metal atom/rGO intercalation. The method further includes the decoration of conductive metals (copper or nickel tungsten) plug on the rGO layer in holes by electroplating process.
1. A method for coating a layer of reduced graphene oxide on the surface of holes in a substrate, comprising:
Step 1 (surface hydrophilic treatment) washing the substrate with alcohol, immersing the substrate in a mixed solution of concentrated sulfuric acid and concentrated hydrogen peroxide, and removing organic remains on the substrate, to offer the surfaces of the substrate and holes carrying —OH groups;
Step 2 (self-assembly of a silane layer) immersing the treated substrate from Step 1 in a silane solution to form a self-assembly silane layer on the surface of the substrate and the holes;
Step 3 (grafting of a polymer layer) immersing the treated substrate from Step 2 in a polymer solution to form a polymer layer on the self-assembly silane layer;
Step 4 (grafting of a graphene oxide (GO) layer) immersing the treated substrate from Step 3 in an alkaline GO solution to graft a GO layer on the polymer layer;
Step 5 (intercalation of metal ions) immersing the treated substrate from Step 4 in a solution of metal ion to intercalate the metal ions into the GO layer, and form a metal ion/GO abrasion; and
Step 6 (formation of a metal atom/rGO composite layer) immersing the treated substrate from Step 5 in a solution of reductant to reduce the metal ion into metal atom, and the GO layer into a reduced graphene oxide (rGO) layer to form a metal atom/rGO composite layer on the substrate surface and the hole surface.
2. The method of claim 1 , wherein the immersion time in Step 1 is 20-40 min and the temperature of the solution is 50-90° C.
3. The method of claim 1 , wherein the silane solution in Step 2 is a 0.5-1.5V % solution of epoxy silane.
4. The method of claim 3 , wherein the silane solution in Step 2 is a solution of 3-(2,3-epoxypropoxy)propyltrimethoxysilane (GPTMS).
5. The method of claim 1 , wherein the immersion time in Step 2 is 15-25 min and the temperature of the solution is 50-70° C.
6. The method of claim 1 , wherein the polymer solution in Step 3 is a 3-10 wt % solution of Polyethyleneimine (PEI).
7. The method of claim 1 , wherein the immersion time in Step 3 is 60-120 min and the temperature of the solution is 40-80° C.
8. The method of claim 1 , wherein the pH value of the alkaline GO solution in Step 4 is 8.5-10.
9. The method of claim 1 , wherein a 0.1M solution of NaOH is added to the GO solution to form the alkaline GO solution in Step 4.
10. The method of claim 1 , wherein the immersion time in Step 4 is 6-12 hours and the temperature of the solution is 15-35° C.
11. The method of claim 1 , wherein the solution of metal ion in Step 5 is a 0.05-0.15M AgNO 3 solution.
12. The method of claim 1 , wherein the immersion time in Step 5 is 20-40 min and the temperature of the solution is 30-70° C.
13. The method of claim 1 , wherein the solution of reductant in Step 6 is a solution selected from the group consisting of HI solution, sodium borohydride solution, ascorbic acid solution, ethanol solution, and hydrazine solution.
14. The method of claim 1 , wherein the immersion time in Step 6 is 1.5-2.5 hours and the temperature of the solution is 30-70° C.
15. The method of claim 1 , wherein a sonication procedure is included in the immersion process of Step 1 to the Step 6.