Patent ID: 8703509

Claim:
A method for manufacturing a substrate for liquid-ejecting heads comprising: preparing a silicon substrate to have a first surface and a second surface opposite to the first surface, the second surface covered with a silicon oxide layer having an opening, and an energy-generating element formed at a side of the first surface of the silicon substrate; etching a portion of the silicon substrate using a first etchant so as to form a depression, on a bottom of which silicon of the silicon substrate is exposed, on the second surface of the silicon substrate, with the silicon oxide layer as a mask, the first etchant offering a lower etching rate on silicon oxide surfaces than on silicon surfaces; and applying a second etchant to the depression, on the bottom of which silicon of the silicon substrate is exposed, so as to etch at least the silicon oxide layer and a portion sandwiched between the depression and the first surface to form a liquid supply port, the second etchant offering a higher etching rate on silicon oxide surfaces than that offered by the first etchant, wherein an insulating layer is formed on the first surface, the insulating layer is not exposed on the bottom when the silicon substrate is exposed on the bottom, the insulating layer is exposed by etching a portion sandwiched between the depression and the first surface with the second etchant, and the insulating layer is removed after the step of etching with the second etchant.