Planar Heater Stack And Method For Making Planar Heater Stack

A heater stack for a micro-fluid ejection device, comprising:

• first strata configured to support and form a fluid heater element responsive to energy from repetitive electrical activation and deactivation to fire repetitive cycles of heating and ejecting of a fluid from an ejection chamber above said fluid heater element, said first strata including a substrate and a heater substrata overlying said substrate;
• said heater substrata including a resistive layer having
• lateral portions spaced apart from each other,
• a central portion extending generally between said lateral portions and defining said fluid heater element of said first strata, and
• transitional portions respectively interconnecting said central portion and lateral portions and extending upwardly and toward one another from said lateral portions so as to elevate said central portion relative to said lateral portions and spaced above said substrate to form a gap extending between said lateral portions and between said central portion and said substrate substantially insulating said substrate from said fluid heater element so as to reduce heat transfer from said fluid heater element to said substrate and thereby increase heat transfer into the fluid in said ejection chamber from firing said repetitive cycles of heating and ejecting of the fluid from the ejection chamber above said fluid heater element;
• and
• said heater substrata also including a conductive layer having separate anode and cathode portions on said resistive layer separated from one another by said central portion of said resistive layer and by said gap underlying said fluid heater element of said central portion of said resistive layer, said anode and cathode portions overlying and deposited on said lateral and transitional portions and extending to a height above said lateral portions of said resistive layer approximately level with a height of said central portion above said substrate such that said anode and cathode portions are interconnected and separated by said central portion of said resistive layer to define said fluid heater element therewith and also provide said heater substrata with a substantially planar upper surface formed by said anode and cathode portions of said conductive layer and said central portion of said resistive layer.