Ink jet printhead with seamlessly coated heater

An inkjet printhead integrated circuit including a multilayered substrate having drive circuitry and a plurality of nozzle arrangements. Each nozzle arrangement includes: a floor having an ink inlet defined therein; a roof spaced apart from the floor; sidewalls extending between the roof and the floor so as to define a nozzle chamber; and a heater element suspended in the chamber and connected to the drive circuitry. When actuation energy is supplied to the heater element from the drive circuitry, a vapor bubble is formed in ink contained in the nozzle chamber resulting in ejection of ink via the ink ejection port.