Method of forming nozzle for injection device and method of manufacturing inkjet head

A method of forming a nozzle, which has a cross-section narrowing stepwise from a rear end toward the front end thereof, for an ejection device by applying etching to a silicon monocrystalline substrate, comprising the steps of:

• forming a resist film on a surface of the silicon monocrystalline substrate;
• forming a first opening pattern, which corresponds to a rear portion of the nozzle at a rear end thereof, in the resist film, by half-etching the resist film;
• forming a second opening pattern, which corresponds to a front portion of the nozzle at the front end thereof, by full-etching a portion of the first opening pattern;
• forming a first groove having a predetermined depth by applying dry-etching to the exposed portion of the silicon monocrystalline substrate by plasma discharge;
• fully etching the remaining portion of said first opening so as to expose the surface of the silicon monocrystalline substrate;
• and
• thereafter forming a second groove having a predetermined depth while the first groove remains at the bottom of the second groove by applying dry-etching to the silicon monocrystalline substrate by plasma discharge.

A method of manufacturing an inkjet head, comprising the steps of:

• forming a nozzle by conducting etching on a silicon substrate, comprising the steps of:
• forming a resist film on a surface of the silicon substrate,
• forming a first opening pattern by removing the resist film at a portion corresponding to a rear end of the nozzle,
• forming a second opening pattern smaller than the first pattern by removing the resist film at a portion corresponding to a front end of the nozzle, and
• applying dry-etching by plasma discharge to exposed portions of the surface of the silicon monocrystalline substrate exposed by the first and second opening patterns to form the nozzle having a cross-section smaller stepwise from the rear end toward the front end;
• bonding a substrate on which an ink passage is formed to the lower side of the silicon substrate provided with the nozzle so as to communicate the nozzle with the ink passage.