Abstract: An improved method is disclosed for forming heater elements for an ink jet printhead. The resistance is more closely controlled by doping a central heater region which is formed relatively thinner than the heavily doped heater regions which are used as the gate and contact areas. The thinner central region can doped relatively heavy in order to more accurately adjust the heater resistance.In another embodiment, the thin layer is amorphous silicon rather than the polysilicon to increase the latitude of the energy input.

Abstract: An ejector for a thermal ink-jet printhead includes a heating element defined on a main surface of a silicon heater chip. A cavity is disposed within the heater chip opposite the side of the heating element exposed to liquid ink. In one embodiment, the heating element is disposed on a narrow pillar which is surrounded by two elongated trenches. In another embodiment, the heating element is suspended over a cavity by narrow supports. In each case, the cavity reduces the thermal mass of the structure supporting the heating element and acts as an insulator to prevent excess heat from being dissipated into the body of the heater chip.