Methods for producing submicron metal line and island arrays
This process results in directed electroless plating of the metal to form discrete metal structures over the entire surface. Because the surface is pre-patterned with passivated regions inert to metal deposition, the metal is directed only to the unstamped regions. This allows the formation of unconnected metal structures without any chemical etching steps. These metallic arrays are varied in size, separation and shape by using gratings of different periodicities and blaze angles as the stamp templates. A variety of well-defined geometric patterns have been fabricated and imaged using scanning probe, scanning electron, and optical microscopies.
1. A method for fabricating planar metal structures on a substrate comprising:
(a) exposing the substrate to hydrophilic silane molecules capable of bonding to the substrate such that the substrate has at least one hydrophobic and at least one hydrophilic region;
(b) exposing the substrate to a metallization precursor such that the hydrophilic regions are activated; and
(c) exposing the substrate to an electroless plating solution, thereby reducing metal onto the hydrophilic regions;
wherein steps (a) through (c) are carried out such that only the metallization precursor layer present between the metal and the substrate.
2. The method according to claim 1 further comprising rinsing the substrate after step (b).
3. The method according to claim 1 further comprising rinsing the substrate after step (c).
4. The method according to claim 3 further comprising drying the substrate.
5. The method according to claim 1 wherein the hydrophobic molecules are capable of crosslinking with each other.
6. The method according to claim 1 wherein the silane molecules comprise n-propyltrimethoxysilane (PTMS).
7. The method according to claim 1 wherein the substrate comprises a material selected from the group consisting of titanium nitride, indium tin oxide, alumina, silicon, and silicon-based materials.
8. The method according to claim 7 wherein the substrate comprises an optically transparent material.
9. The method according to claim 8 wherein the substrate comprises silica.
10. The method according to claim 1 wherein the non-hydrophilic regions are inert to metal deposition.
11. The method according to claim 1 wherein the metallization precursor comprises Sn 2+ .
12. The method according to claim 1 wherein the electroless plating solution comprises a metal salt selected from the group consisting of Ag, Ni, Sn, Au, Pd, Pt, and Cu.
13. The method according to claim 1 , wherein step a) is carried out by printing with a stamp and wherein step a) is carried out at least twice before step c) is carried out.