Methods for fabricating planar heater structures for ejection devices

A method for fabricating a planar heater structure for an ejection device, the method comprising:

• providing a substrate wafer, the substrate wafer comprising a plurality of plugs configured therewithin, each plug of the plurality of plugs being formed as an electrical connection and composed of a first metallic material;
• depositing and patterning a layer of a second metallic material over the substrate wafer, the patterning leaving a patterned layer of isolated sections of electrical conductors aligned vertically above said each plug and exposing a surface of the substrate wafer;
• providing a layer of a dielectric material of a predetermined thickness over the surface of the substrate wafer and the patterned layer of the isolated sections of electrical conductors;
• conducting chemical mechanical polishing of the layer of the dielectric material and a topmost portion of the patterned layer to form a planarized top surface exposing the patterned layer of the isolated sections of electrical conductors;
• cleaning the planarized top surface;
• and thereafter forming a resistive heater element to eject fluid, including
• depositing and patterning a resistor film over the planarized top surface thereby connecting either ends of the resistor film to the isolated sections of electrical conductors and to said each plug;
• depositing one or more blanket films over the patterned resistor film;
• and
• patterning and etching the one or more blanket films.