Depositing bulk or micro-scale electrodes
Thicker electrodes are provided on microelectronic device using thermo-compression bonding. A thin-film electrical conducting layer forms electrical conduits and bulk depositing provides an electrode layer on the thin-film electrical conducting layer. An insulating polymer layer encapsulates the electrically thin-film electrical conducting layer and the electrode layer. Some of the insulating layer is removed to expose the electrode layer.
1. A method of fabricating a microelectrode device, consisting of the steps of:
providing a device body having providing a device body having an underlying electrically insulating layer by depositing an electrically insulating polymer layer on a substrate,
providing an electrical conductive thin-film layer on said underlying electrically insulating layer by depositing an electrical conductive thin-film layer on said underlying electrically insulating layer, wherein said electrical conductive thin-film layer includes an electrode region, a bond pad region, and an electrical conduit between said electrode region and said bond pad region,
providing at least one electrode embedded in said device body, wherein said step of providing at least one electrode embedded in said device body includes bulk depositing an electrode material on said electrical conducting thin-film layer in said electrode region,
thermocompressively bonding said bulk deposited electrode material to said electrical conductive thin-film layer,
depositing an encapsulating electrically insulating layer on said electrical conductive thin-film layer and said bulk deposited electrode material,
removing said encapsulating electrically insulating layer covering said bulk deposited electrode material, and
releasing said device body from said substrate.
2. The method of fabricating a microelectrode device of claim 1 wherein said step of bulk depositing said electrode material on said electrical conducting thin-film layer in said electrode region comprises bulk depositing said electrode material on said electrical conducting thin-film layer in said electrode region at a thickness within the range of 1 to 50 micrometers.
3. The method of fabricating a microelectrode device of claim 1 wherein said step of bulk depositing said electrode material on said electrical conducting thin-film layer in said electrode region comprises bulk depositing a metal electrode material on said electrical conducting thin-film layer in said electrode region.
4. The method of fabricating a microelectrode device of claim 1 wherein said step of bulk depositing said electrode material on said electrical conducting thin-film layer in said electrode region comprises bulk depositing said electrode material on said electrical conducting thin-film layer in said electrode region using a combination of pressure, elevated temperature, and ultrasonic energy to bond said electrode material to said electrical conducting electrical conducting electrical conducting thin-film layer.
5. The method of fabricating a microelectrode device of claim 1 wherein said step of bulk depositing said electrode material on said electrical conducting thin-film layer in said electrode region comprises bulk depositing platinum, iridium, titanium, doped diamond, tantalum, or niobium, or an alloy of platinum, iridium, titanium, doped diamond, tantalum, or niobium on said electrical conducting thin-film layer in said electrode region.
6. The method of fabricating a microelectrode device of claim 1 wherein said step of bulk depositing said electrode material on said electrical conducting thin-film layer in said electrode region comprises depositing said electrode material using electroplating or electrodeposition or physical vapor deposition.
7. The method of fabricating a microelectrode device of claim 1 wherein said step of bulk depositing said electrode material on said electrical conducting thin-film layer in said electrode region comprises depositing said electrode material using direct ink writing.