Patent ID: 7238293

Claim:
A print head die forming method comprising: forming a plurality of fluid-handling passageways and ejection chambers over a first surface of a substrate; subsequent to said forming a plurality of fluid-handling passageways and ejection chambers, forming a first patterned masking layer sufficient to expose a desired area of a second generally opposing surface of the substrate; after forming the first patterned masking layer, forming a second patterned masking layer sufficient to expose less than the entirety of the desired area of the second surface; forming a slot portion in the substrate through the second patterned masking layer; and removing additional substrate material to form a fluid-handling slot sufficient to supply fluid from the second surface through the substrate to the first surface and the fluid handling passageways, the fluid-handling slot extending along a long axis that lies generally parallel to the first surface, wherein the fluid-handling slot has a cross-section taken transverse the long axis that is defined, at least in part, by one sidewall, wherein at least a first portion of the one sidewall is generally parallel to the first surface, and wherein a second portion of the one sidewall is generally perpendicular to the first surface, and wherein a third portion of the sidewall extends from the second portion to and in contact with the first surface of the substrate and defines an obtuse angle with the second portion as measured through the fluid-handling slot.