Embedded noble metal electrodes in microfluidics
A technique relates to manufacturing a nanogap. An oxide layer is disposed on top of a substrate. A release layer is disposed in a pattern on top of the oxide layer. A patterned trench is etched into the oxide layer using the pattern of the release layer. A metal layer is disposed on the release layer and in the patterned trench. A polish removes the release layer, thereby removing both the release layer and a portion of the metal layer having been disposed on top of the release layer, such that the metal layer remaining includes a first metal part and a second metal part connected by a metal nanowire. The metal layer remaining is coplanar with the oxide layer. A nanochannel is formed in the oxide layer in a region of the metal nanowire. The nanogap is formed in the metal nanowire separating the first and second metal parts.
1. A method of manufacturing a nanogap, the method comprising:
disposing an oxide layer on top of a substrate;
disposing a release layer in a pattern on top of the oxide layer;
etching a patterned trench into the oxide layer using the pattern of the release layer;
disposing a metal layer on the release layer and in the patterned trench, such that the metal layer is disposed on top of the oxide layer in the patterned trench;
performing a polish to remove the release layer, thereby removing both the release layer and a portion of the metal layer having been disposed on top of the release layer, such that the metal layer remaining includes a first metal part and a second metal part connected by a metal nanowire, wherein the metal layer remaining is coplanar with the oxide layer;
forming a nanochannel in the oxide layer in a region of the metal nanowire, wherein the metal nanowire intersects the nanochannel; and
forming the nanogap in the metal nanowire, such that the first metal part and the second metal part are separated by the nanogap, the nanogap being parallel to the nanochannel and perpendicular to the metal nanowire;
wherein the nanogap, the metal part, the second metal part, and the nanochannel lie in a same plane.
2. The method of claim 1 , wherein performing the polish to remove the release layer comprises performing mechanical polishing using water to remove the release layer.
3. The method of claim 2 , wherein the mechanical polishing with the water excludes a chemical slurry of abrasive particles, thereby causing no scratches to the metal layer in the patterned trench and causing no removal of the metal layer in the patterned trench.
4. The method of claim 3 , wherein shear force by a pad during the mechanical polishing breaks a bond between the release layer and the oxide layer underneath.
5. The method of claim 1 , further comprising forming a cover over at least the nanochannel, the nanogap, and the first and second metal parts.
6. The method of claim 1 , wherein the nanogap is formed by cutting the metal nanowire to separate the first metal part and the second metal part.
7. The method of claim 1 , wherein the metal layer is a noble metal.
8. The method of claim 1 , wherein the metal layer comprises at least one of palladium, platinum, and gold.
9. The method of claim 1 , wherein the substrate comprises silicon; and
wherein the oxide layer is silicon dioxide.
10. The method of claim 1 , wherein the metal layer is embedded in the oxide layer such that a top metal surface of the metal layer is coplanar with a top oxide surface of the oxide layer having the nanochannel.
11. The method of claim 1 , further comprising after performing the polish to remove the release layer, disposing a coating of another oxide layer on top of the metal layer and the oxide layer.
12. The method of claim 1 , wherein a gap size of the nanogap formed in the metal nanowire is about 2 nanometers.