Inkjet printhead with ink supply passage formed from both sides of the wafer by overlapping etches

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.

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.

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.