Fabrication of three-dimensional high surface area electrodes
A method for fabricating three dimensional high surface electrodes is described. The methods including the steps: designing the pillars; selecting a material for the formation of the pillars; patterning the material; transferring the pattern to form the pillars; insulating the pillars and providing a metal layer for increased conductivity. Alternative methods for fabrication of the electrodes and fabrication of the electrodes using CMOS are also described.
1. A method for fabricating three dimensional high surface electrodes, comprising:
designing a plurality of pillars by optimizing one or more characteristics of the pillars, wherein the plurality of pillars corresponds to one or more electrodes dependent on an isolation provided to the plurality of pillars;
applying a resist onto a substrate, wherein the substrate is silicon or silicon alloy;
patterning the resist, wherein the patterning defines the plurality of pillars to be formed on the substrate;
removing selected portions of the substrate via etching corresponding to the pattern of the resist to form the plurality of pillars, the etching forming a pillar with an aspect ratio greater than 5;
insulating a first group of pillars of the plurality of pillars from other pillars of the plurality of pillars to form one distinct electrode by forming an insulator layer with complete and uniform coverage over the first group of pillars of the plurality of pillars; and
depositing a 10 nm to 500 nm metal layer on the plurality of pillars to increase the conductivity of a surface of the electrode, wherein the metal layer coverage is complete and uniform over the plurality of pillars.
2. The method according to claim 1 , wherein the thickness of the insulator layer is between 50 nm and 250 nm.
3. A method for fabricating three dimensional high surface electrodes from CMOS on a metal that is not silicon, comprising:
designing a plurality of pillars by optimizing one or more characteristics of the pillars, wherein the plurality of pillars corresponds to one or more electrodes dependent on an isolation provided to the plurality of pillars;
selecting a top most metal layer from the CMOS where the pillars will be formed, wherein the top most metal layer is not silicon;
applying a resist onto the top most metal layer of the CMOS;
patterning the resist, wherein the patterning defines where the plurality of pillars will be formed on the top most metal layer of the CMOS;
removing selected portions of the top most metal layer of the CMOS via etching corresponding to the pattern of the resist to form the plurality of pillars, the etching forming a pillar with an aspect ratio greater than 5; and
depositing a 10 nm to 500 nm metal layer on the plurality of pillars to increase conductivity of a surface of the electrode, wherein a coverage of the metal layer coverage is complete and uniform over the plurality of pillars,
wherein the method for fabricating is performed at temperatures below 500° C.
4. The method according to claim 1 , wherein the thickness of the metal layer is between 50 nm and 250 nm.
5. The method according to claim 1 , wherein the pillars have an aspect ratio between 15 and 20.
6. The method for fabricating three dimensional high surface electrodes according to claim 1 , further comprising:
depositing a plurality of particles on top of the metal layer of the plurality of pillars to increase the surface area of the pillars,
wherein
the particles are deposited via spray or spin techniques, and
the particles are selected corresponding to a size of a species to be detected by the electrode.
7. The method according to claim 6 , wherein the particles are either nanoparticles or microparticles.
8. The method according to claim 1 , wherein the depositing of the metal layer on the plurality of pillars is performed using pressure and a stage adapted to be rotated and tilted with respect to the metal being deposited.
9. The method according to claim 8 , wherein the pressure used during metal deposition is 20 mTorr.
10. The method according to claim 1 , wherein the temperature is below 250° C.
11. The method according to claim 3 , wherein the thickness of the metal layer is between 50 nm and 250 nm.
12. The method according to claim 3 , wherein the pillars have an aspect ratio between 15 and 20.
13. The method for fabricating three dimensional high surface electrodes according to claim 3 , further comprising:
depositing a plurality of particles on top of the metal layer of the plurality of pillars to increase the surface area of the pillars,
wherein
the particles are deposited via spray or spin techniques, and
the particles are selected corresponding to a size of a species to be detected by the electrode.
14. The method according to claim 3 , wherein the depositing of the metal layer on the plurality of pillars is performed using pressure and a stage adapted to be rotated and tilted with respect to the metal being deposited.
15. The method according to claim 3 , wherein the temperature is below 250° C.