| abstract |
A monolithic printhead is formed using integrated circuit techniques. Thin film layers, including ink ejection elements, are formed on a top surface of a silicon substrate. The various layers are etched to provide conductive leads to the ink ejection elements. At least one ink feed hole is formed through the thin film layers for each ink ejection chamber. A protection layer is formed over the ink feed holes. An orifice layer is formed on the top surface of the thin film layers to define the nozzles and ink ejection chambers. A first trench etch is performed to etch the bottom surface of the substrate. The protection layer is then removed. A second trench etch then self-aligns the trench walls with the ink feed holes. In another embodiment, portions of a field oxide layer, forming a bottom layer in the thin film stack, act as the protection layer within the ink feed openings, and the field oxide portions are removed prior to the second trench etch. |