According to an example, a fluid ejection device may include a substrate, a resistor positioned on the substrate, an overcoat layer positioned over the resistor, a fluidics layer having surfaces that form a firing chamber about the resistor, in which the overcoat layer is positioned between the resistor and the firing chamber, and a thin film membrane covering the surfaces of the fluidics layer that form the firing chamber and a portion of the overcoat layer that is in the firing chamber.