An inkjet printhead with nozzles 4 and liquid passages 31, 32 leading to each
nozzle. The nozzles, ejection actuators 14, associated drive circuitry 22 and liquid passage 31, 32 being formed on and through a
wafer 21 using lithographically masked
etching technique, such that the
wafer has a droplet ejection side and a liquid
supply side. Each of the liquid passages is formed by
etching a hole 31 partially through the
wafer 21 from the droplet ejection side, and
etching a passage from the liquid
supply side of the wafer 21 to the hole 31.
Etching a hole 31 into the wafer 21 from the droplet ejection side means the ink supply passage 32 can stop short of the interface between the
dielectric 23 and the wafer 21 to prevent the etchant from tracking sideways and damaging the drive circuitry 22. As the inlet hole 31 is relatively shallow, the removal of the
resist is not overly difficult. However, setting the depth of the supply passage etch so that it overlaps the blind end of the hole by more than the combined tolerances of both etching processes ensures an adequate fluid connection to the
nozzle. This permits a more compact overall design and higher
nozzle packing density.