A nozzle cell of a printhead is provided which has a multi-layer substrate defining a fluid inlet, side walls extending from the substrate around the fluid inlet and comprising walls of silicon nitride encapsulating hardened photoresist, an apertured roof supported by the side walls to define a chamber, and a heater within the chamber, the heater heating the fluid in the chamber so that bubbles are generated therein to cause ejection of the fluid from a nozzle defined with the apertured roof.