Fabrication of ink fill slots in thermal ink-jet printheads utilizing chemical micromachining

A method for fabricating ink fill slots for fluidically communicating with ink feed channels in thermal ink-jet printheads, comprising:

• (a) providing a silicon substrate having a <100>
• or <110>
• crystallographic orientation and two opposed, substantially parallel major surfaces, defining a primary surface and a secondary surface;
• (b) forming an insulating dielectric layer on both said surfaces;
• (c) patterning said insulating dielectric layer on said secondary surface to expose underlying portions of said silicon substrate;
• (d) etching part way through said silicon substrate with an anisotropic etchant at said exposed portions to thereby form a portion of said ink fill slot;
• (e) forming and defining thin film resistor elements and conductive traces on said insulating dielectric layer on said primary surface;
• (f) precisely etching from said primary surface to connect with said portion of said ink fill slot to thereby completely form said ink fill slot and to controllably extend the portion of said ink fill slot terminating at said primary surface toward said ink feed channels to cause a widening thereof;
• and
• (g) forming a barrier layer on the major surface of said dielectric material and defining openings therein to expose said resistor elements to define a drop ejection chamber and to provide said ink feed channels from each said resistor element to a terminus region, said terminus region fluidically communicating with said ink fill slot for introducing ink from a reservoir to said drop ejection chamber.