Method for manufacturing a monolithic ink-jet printhead

A method for manufacturing a monolithic ink-jet printhead, comprising:

• preparing a silicon substrate;
• forming a first silicon oxide layer by oxidizing the surface of the substrate;
• forming, on the substrate, a MOS integrated circuit including a MOSFET for driving the heater and electrodes connected to the heater;
• forming a heater on a second silicon oxide layer;
• forming, inside the heater, a nozzle for ejecting ink by etching the second silicon oxide layer to a diameter smaller than that of the heater;
• forming a manifold for supplying ink by etching a bottom surface of the substrate;
• forming an ink chamber having a diameter larger than that of the heater and having a hemispheric shape by etching the substrate exposed by the nozzle;
• and
• forming an ink channel for connecting the ink chamber to the manifold by etching the bottom of the ink chamber through the nozzle, wherein forming the MOS integrated circuit includes:
• depositing a silicon nitride layer on the first silicon oxide layer;
• etching a portion of the first silicon oxide layer and the silicon nitride layer;
• forming a field oxide layer thicker than the first silicon oxide layer around a region in which the MOSFET is to be formed;
• removing the first silicon oxide layer and the silicon nitride layer;
• forming a second silicon oxide layer on the substrate;
• forming a gate of the MOSFET on a gate oxide layer using the second silicon oxide layer as the gate oxide layer;
• forming source and drain regions of the MOSFET under the second silicon oxide layer;
• and
• forming electrodes for electrically connecting the heater to the MOSFET.