Patent ID: RE44945

Claim:
A manufacturing method for a substrate for an ink jet head including an energy generating element for generating energy used to eject ink and an ink supply port for supplying the element with ink, said method comprising: providing a substrate having the element, a sacrificial layer of material having an etching speed which is higher than that of silicon on an area where said ink supply port is going to be formed at a side of a first surface, and an etching mask layer having an opening at a position corresponding to the ink supply port on a second surface which is a back surface of opposite the first surface of said substrate and which has a plane direction < 100 >; forming recesses in the first surface in substrate in an area of the substrate exposed by the opening at the second surface in first and second rows extending in a longitudinal direction of said opening in sides of a center of said opening with respect to a widthwise direction of said opening, wherein said recesses in the first and second rows include a recess satisfying T−(X−L/2)×tan 54.7°≧D≧T−X×tan 54.7° where L (μm) is a length of the sacrificial layer in a widthwise direction of the sacrificial layer, T (μm) is a thickness of said substrate, X (μm) is a distance from a center of said sacrificial layer in a the widthwise direction to centers of said recesses, and D is a depth of said recesses; and forming said ink supply port by crystal anisotropic etching of said substrate through said opening.