Printhead integrated circuit with suspended heater elements
View Patent ↗An inkjet printhead integrated circuit comprises a silicon substrate having a layer of drive circuitry and a passivation layer over the drive circuitry layer. The passivation layer defines a plurality of vias exposing a plurality of contacts in the underlying drive circuitry. Sidewalls extend from the passivation layer and meet with a nozzle plate spaced apart from the passivation layer. The nozzle plate and the sidewalls together form a plurality of ink chambers, each ink chamber having a nozzle opening defined in the nozzle plate and an ink inlet. A heater element is suspended in each of the ink chambers. Each heater element is electrically connected to a respective pair of contacts in the drive circuitry layer through a respective pair of the vias.
1. An inkjet printhead integrated circuit comprising:
a silicon substrate having at least one layer of drive circuitry and a passivation layer over the drive circuitry layer, the passivation layer defining a plurality of vias exposing a plurality of contacts in said underlying drive circuitry;
sidewalls extending from the passivation layer and meeting with a nozzle plate spaced apart from the passivation layer, such that the nozzle plate and the sidewalls together form a plurality of ink chambers, each ink chamber having a nozzle opening defined in said nozzle plate and an ink inlet; and
a heater element suspended in each of said ink chambers, each heater element being electrically connected to a respective pair of contacts in said drive circuitry layer through a respective pair of said vias.
2. The printhead integrated circuit of claim 1 , wherein said nozzle plate is comprised of at least one material selected from the group consisting of: silicon oxide and silicon nitride.
3. The printhead integrated circuit of claim 2 , wherein said nozzle plate is coated with a hydrophobic material.
4. The printhead integrated circuit of claim 3 wherein said hydrophobic material is covalently bonded to said nozzle plate.
5. The printhead integrated circuit of claim 1 , wherein a plurality of ink inlet passages are defined through said drive circuitry layer and said passivation layer, each ink inlet passage being fluidically connected to each ink inlet.
6. The printhead integrated circuit of claim 5 , wherein said at least one drive circuitry layer is comprised of a plurality of metal layers interposed with dielectric layers, wherein said plurality of metal layers together define a seal ring for each ink inlet passage.
7. The printhead integrated circuit of claim 1 , wherein each heater element is comprised of titanium aluminum nitride.
8. The printhead integrated circuit of claim 1 , wherein said nozzle plate is supported at least partially by encapsulated photoresist.
9. The printhead integrated circuit of claim 8 , wherein said photoresist is encapsulated by said sidewalls and said nozzle plate.