MEMS jetting structure for dense packing

1. A fluid ejector, comprising:

a fluid ejection module comprising a die having a plurality of nozzles formed in a common bottom surface thereof, having a plurality of conduits that connect the plurality of nozzles to a top surface of the die, and having a plurality of fluid ejection actuators arranged in a matrix, each fluid ejection actuator configured to cause a fluid to be ejected from a single corresponding nozzle such that ejection of fluid from each nozzle is controlled by a corresponding fluid ejection actuator; and

an interposer that is a body having a lower surface secured to a top surface of the die, the interposer comprising a plurality of electrical connections to the fluid ejection module, the interposer comprising a plurality of fluid passages that include a pair of fluid passages for every fluid ejection actuator, each fluid ejection actuator located between the interposer and the corresponding nozzle;

wherein the pair of fluid passages is an inlet channel and an outlet channel for each corresponding fluid ejection actuator, the inlet channels and outlet channels fluidically coupled to the and passing through the interposer.

2. The fluid ejector of claim 1 , wherein the fluid passages are coated with a barrier layer.

3. The fluid ejector of claim 2 , wherein the barrier layer comprises titanium, tantalum, aluminum oxide, or silicon oxide.

4. The fluid ejector of claim 1 , further comprising a barrier layer between the interposer and the fluid ejection module.

5. The fluid ejector of claim 1 , further comprising a plurality of gold bumps on the top surface of the die, each gold bump configured to contact an electrode of a corresponding fluid ejection actuator to an electrical connection of the interposer.

6. The fluid ejector of claim 1 , wherein the interposer is an integrated circuit interposer having a plurality of transistors formed thereon.

7. The fluid ejector of claim 1 , wherein the substrate includes a silicon layer.

8. The fluid ejector of claim 1 , wherein the interposer is attached to an actuation layer of the fluid ejection module.

9. The fluid ejector of claim 1 , wherein the interposer is in direct mechanical contact with the die and is in direct electrical contact with a substrate of the die.

10. The fluid ejector of claim 6 , wherein the integrated circuit interposer is an application-specific integrated circuit.

11. The fluid ejector of claim 1 , wherein the lower surface of the interposer is separated from the top surface of the die by an air gap, wherein the fluid ejector comprises a plurality of electrical leads extending between the plurality of electrical connections of the interposer and electrodes of the fluid ejection actuators, and wherein the fluid ejector comprises a plurality of fluid connections extending between the plurality of fluid passages in the actuator and the plurality of conduits in the die.

12. The fluid ejector of claim 11 , wherein each fluid ejection actuator comprises a piezoelectric actuator having a movable membrane and a portion of the air gap is positioned above the membrane.

13. The fluid ejector of claim 11 , wherein the electrical leads comprise conductive bumps on the top surface of the die and that extend across the gap.

14. The fluid ejector of claim 11 , wherein the electrical leads comprise conductive bumps on the top surface of the die and that extend across the gap.

15. The fluid ejector of claim 11 , wherein the plurality of fluid connections comprise annular bodies of a barrier material that extend across the gap with an aperture in each annular body aligned between a fluid passages in the actuator and a conduit in the die.

16. The fluid ejector of claim 15 , wherein the barrier material is a photoresist.