Inkjet printhead with ink supply passage formed from both sides of the wafer by overlapping etches
View Patent ↗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.
1. An inkjet printhead comprising:
a wafer providing a supporting substrate, the wafer having a drop ejection side and a liquid supply side;
a plurality of nozzles, each nozzle having a liquid passage leading to it from the liquid supply side of the wafer for providing ejectable liquid to the nozzle;
drop ejection actuators and associated drive circuitry corresponding to each nozzle respectively;
the nozzles, ejection actuators, associated drive circuitry and liquid passage being formed on and through the wafer using lithographically masked etching techniques; wherein,
each of the liquid passages is formed by etching a blind hole into the wafer from the drop ejection side, and etching a supply passage from the liquid supply side of the wafer to the hole; such that,
the blind hole extends into the wafer passed the drive circuitry; and,
the supply passage is etched to a depth that extends passed the blind end of the hole by an overlap greater than the sum of the fabrication tolerances of both etch processes.
2. An inkjet printhead according to claim 1 wherein the overlap is between 5 microns and 30 microns.
3. An inkjet printhead according to claim 1 wherein the overlap is between 10 microns and 20 microns.
4. An inkjet printhead according to claim 1 wherein the width of the supply passage is greater than 14 microns.
5. An inkjet printhead according to claim 1 wherein the width of the supply passage is less than 28 microns.
6. An inkjet printhead according to claim 1 wherein the drop ejection actuators are thermal bend actuators.
7. An inkjet printhead according to claim 1 wherein the drop ejection actuators are gas bubble generating heater elements.
8. An inkjet printhead according to claim 7 further including a plurality of nozzle chambers, each nozzle chamber corresponding to a respective nozzle; wherein,
at least one the of the gas bubble generating heater elements are disposed in each of the nozzle chambers respectively; such that,
a bubble forming liquid can be supplied to the nozzle chamber for thermal contact with at least one of the bubble generating heater elements so that a bubble of the bubble forming liquid generated by one of the heater elements causes a droplet of the ejectable liquid to be ejected from the nozzle.
9. An inkjet printhead according to claim 8 wherein the bubble forming liquid is the same as the ejected liquid.
10. An inkjet printhead according to claim 1 wherein the printhead is a pagewidth printhead.
11. A method of ejecting drops of an ejectable liquid from an inkjet printhead, the printhead comprising a wafer providing a supporting substrate, the wafer having a drop ejection side and a liquid supply side, a plurality of nozzles, each nozzle having a liquid passage leading to it from the liquid supply side of the wafer for providing ejectable liquid to the nozzle, drop ejection actuators and associated drive circuitry corresponding to each nozzle respectively, the nozzles, ejection actuators, associated drive circuitry and liquid passage being formed on and through the wafer using lithographically masked etching techniques; wherein,
each of the liquid passages is formed by etching a blind hole into the wafer from the drop ejection side, and etching a supply passage from the liquid supply side of the wafer to the hole; such that,
the blind hole extends into the wafer passed the drive circuitry; and,
the supply passage is etched to a depth that extends passed the blind end of the hole by an overlap greater than the sum of the fabrication tolerances of both etch processes, the method of ejecting drops comprising the steps of:
providing the ejectable liquid to each of the nozzles using the associated liquid passage; and
actuating the drop ejection actuator to eject drops of the ejectable liquid from the nozzle.
12. A method according to claim 11 wherein the overlap is between 5 microns and 30 microns.
13. A method according to claim 11 wherein the overlap is between 10 microns and 20 microns.
14. A method according to claim 11 wherein the width of the supply passage is greater than 14 microns.
15. A method according to claim 11 wherein the width of the supply passage is less than 28 microns.
16. A method according to claim 11 wherein the drop ejection actuators are thermal bend actuators.
17. A method according to claim 11 wherein the droplet ejection actuators are gas bubble generating heater elements.
18. A method according to claim 17 further including a plurality of nozzle chambers, each nozzle chamber corresponding to a respective nozzle; wherein,
at least one the of the gas bubble generating heater elements are disposed in each of the nozzle chambers respectively; such that,
a bubble forming liquid can be supplied to the nozzle chamber for thermal contact with at least one of the bubble generating heater elements so that a bubble of the bubble forming liquid generated by one of the heater elements causes a drop of the ejectable liquid to be ejected from the nozzle.
19. A method according to claim 18 wherein the bubble forming liquid is the same as the ejected liquid.
20. A method according to claim 11 wherein the printhead is a pagewidth printhead.
21. A method of fabricating inkjet printheads, the printhead comprising a wafer providing a supporting substrate, the wafer having a drop ejection side and a liquid supply side, a plurality of nozzles, each nozzle having a liquid passage leading to it from the liquid supply side of the wafer for providing ejectable liquid to the nozzle, drop ejection actuators and associated drive circuitry corresponding to each nozzle respectively, the method comprising the steps of:
forming the nozzles, ejection actuators, associated drive circuitry and liquid passage on and through the wafer using lithographically masked etching techniques; including,
forming each of the liquid passages by etching a blind hole into the wafer from the drop ejection side;
filling the hole with resist;
etching a supply passage from the liquid supply side of the wafer to the hole and subsequently stripping the resist from the hole; such that,
the blind hole extends into the wafer passed the drive circuitry; and,
the supply passage is etched to a depth that extends passed the blind end of the hole by an overlap greater than the sum of the fabrication tolerances of both etch processes.
22. A method according to claim 21 wherein the overlap is between 5 microns and 30 microns.
23. A method according to claim 21 wherein the overlap is between 10 microns and 20 microns.
24. A method according to claim 21 wherein the width of the supply passage is greater than 14 microns.
25. A method according to claim 21 wherein the width of the supply passage is less than 28 microns.
26. A method according to claim 21 wherein the droplet ejection actuators are thermal bend actuators.
27. A method according to claim 21 wherein the droplet ejection actuators are gas bubble generating heater elements.
28. A method according to claim 27 further including a plurality of nozzle chambers, each nozzle chamber corresponding to a respective nozzle; wherein,
at least one the of the gas bubble generating heater elements are disposed in each of the nozzle chambers respectively; such that,
a bubble forming liquid can be supplied to the nozzle chamber for thermal contact with at least one of the bubble generating heater elements so that a bubble of the bubble forming liquid generated by one of the heater elements causes a droplet of the ejectable liquid to be ejected from the nozzle.
29. A method according to claim 28 wherein the bubble forming liquid is the same as the ejected liquid.
30. A method according to claim 21 wherein the printhead is a pagewidth printhead.
31. A printer system incorporating an inkjet printhead comprising:
a wafer providing a supporting substrate, the wafer having a drop ejection side and a liquid supply side;
a plurality of nozzles, each nozzle having a liquid passage leading to it from the liquid supply side of the wafer for providing ejectable liquid to the nozzle;
drop ejection actuators and associated drive circuitry corresponding to each nozzle respectively;
the nozzles, ejection actuators, associated drive circuitry and liquid passage being formed on and through the wafer using lithographically masked etching techniques; wherein,
each of the liquid passages is formed by etching a blind hole into the wafer from the drop ejection side, and etching a supply passage from the liquid supply side of the wafer to the hole; such that,
the blind hole extends into the wafer passed the drive circuitry; and,
the supply passage is etched to a depth that extends passed the blind end of the hole by an overlap greater than the sum of the fabrication tolerances of both etch processes.
32. A printer system according to claim 31 wherein the overlap is between 5 microns and 30 microns.
33. A printer system according to claim 31 wherein the overlap is between 10 microns and 20 microns.
34. A printer system according to claim 31 wherein the width of the supply passage is greater than 14 microns.
35. A printer system according to claim 31 wherein the width of the supply passage is less than 28 microns.
36. A printer system according to claim 31 wherein the droplet ejection actuators are thermal bend actuators.
37. A printer system according to claim 31 wherein the droplet ejection actuators are gas bubble generating heater elements.
38. A printer system according to claim 37 further including a plurality of nozzle chambers, each nozzle chamber corresponding to a respective nozzle; wherein,
at least one the of the gas bubble generating heater elements are disposed in each of the nozzle chambers respectively; such that,
a bubble forming liquid can be supplied to the nozzle chamber for thermal contact with at least one of the bubble generating heater elements so that a bubble of the bubble forming liquid generated by one of the heater elements causes a drop of the ejectable liquid to be ejected from the nozzle.
39. A printer system according to claim 38 wherein the bubble forming liquid is the same as the ejected liquid.
40. A printer system according to claim 31 wherein the printhead is a pagewidth printhead.