Method of fabricating an ink jet printhead
View Patent ↗An ink jet printhead chip includes a wafer substrate. A CMOS drive circuitry layer is positioned on the wafer substrate. A plurality of nozzle arrangements is positioned on the wafer substrate and the CMOS drive circuitry layer. Each nozzle arrangement includes nozzle chamber walls and a roof wall that define a nozzle chamber and an ink ejection port defined in the roof wall. A micro-electromechanical actuator is connected to the CMOS drive circuitry layer. The actuator has at least one movable member that is positioned to act on ink in the nozzle chamber to eject the ink from the ink ejection port on receipt of a signal from the drive circuitry layer. The movable member is spaced between 2 microns and 15 microns from the CMOS drive circuitry layer.
1. A method of fabricating an ink jet printhead chip having a wafer substrate with ink supply channels defined therethrough, a CMOS drive circuitry layer positioned on the wafer substrate and a plurality of nozzle arrangements positioned on the wafer substrate and the CMOS drive circuitry layer so as to be associated with respective ones of the ink supply channels, each nozzle arrangement having nozzle chamber walls and a roof wall that define a nozzle chamber and an ink ejection port in the roof wall and a micro-electromechanical, cantilevered actuator connected to the CMOS drive circuitry layer and spaced from the respective ink supply channel in the wafer substrate, the cantilevered actuator having at least one movable member at its free end, the cantilevered actuator being configured to move said movable member so as to eject the ink from the ink ejection port upon being heated on receipt of a signal from the drive circuitry layer, the method comprising, for each nozzle arrangement, the steps of:
depositing between 2 microns and 15 microns of a first sacrificial material on the CMOS drive circuitry layer to define a deposition area;
forming said cantilevered actuator on said deposition area;
forming the nozzle chamber walls and roof wall by at least one of a deposition and an etching process to define said nozzle chamber; and
back etching the wafer substrate to form said ink supply channel in fluid communication with said nozzle chamber and spaced from said cantilevered actuator,
wherein the step of forming said cantilevered actuator comprises:
depositing and etching a first layer of actuator material;
forming at least one heater element on said first layer of actuator material,
said heater element being in electrical contact with said drive circuitry;
depositing and etching a second layer of actuator material over said at least one heater element and said first layer to form at least part of each micro-electromechanical, cantilevered actuator, the heating element causing said heating of the cantilevered actuator so as to cause said movement of the movable member.
2. A method as claimed in claim 1 which includes the step of depositing between 5 microns and 12 microns of the first sacrificial material on the CMOS drive circuitry layer.
3. A method as claimed in claim 2 , which includes the step of depositing between 6 and 10 microns of the first sacrificial material on the CMOS drive circuitry layer.
4. A method as claimed in claim 1 , in which the step of forming the nozzle chamber walls and roof wall of each nozzle arrangement includes the steps of
depositing a second sacrificial material on the layer of actuator material to define a deposit area for at least part of the nozzle chamber walls and the roof wall,
depositing a structural material on the deposit area, and
etching the structural material to form the at least part of the nozzle chamber walls and the roof wall.