Liquid ejection head and method for manufacturing the same

A method for manufacturing a liquid ejection head chip in which a liquid ejection unit having a plurality of ejection orifices for ejecting a liquid, a flow path in communication with the ejection orifices, and an energy generating element that generates energy for ejecting the liquid is provided on an upper surface composed of a (100) surface of a silicon single-crystal substrate, the method comprising the steps of:

• (a) building a chip array, which is formed of the liquid ejection head chips arranged, onto the upper surface formed of the (100) surface of a common substrate composed of silicon single crystal;
• and
• (b) dividing each liquid ejection head chip apart from the chip array provided on the common substrate such that opposing side surfaces of the liquid ejection head chip are formed of (111) surfaces of the silicon single crystal and the angles of the opposing side surfaces relative to the (100) surface are supplementary to each other, thereby obtaining the liquid ejection head chip,
• wherein the step (b) includes the steps of:
• (b-1) providing an etching mask pattern for forming one of the opposing side surfaces of each of the liquid ejection head chips, which constitute the chip array, on the upper surface of the common substrate and carrying out anisotropic etching from the upper surface of the common substrate to form the (111) surface, at a position where the one of the opposing side surfaces is to be formed, in the direction of the thickness of the common substrate;
• (b-2) providing an etching mask pattern for forming the other of the opposing side surfaces of each of the liquid ejection head chips, which constitute the chip array, on a lower surface of the common substrate and carrying out anisotropic etching from the lower surface of the common substrate to form the (111) surface, at a position where the other of the opposing side surfaces is to be formed, in the direction of the thickness of the common substrate;
• and
• (b-3) cutting the common substrate at a position in the (111) surface obtained by the steps (b-1) and (b-2), at which position the surfaces having the angles relative to the (100) surface that are supplementary to each other will remain, thereby obtaining side surfaces composed of the opposing (111) surfaces.