Method for manufacturing mems devices using multiple photoacid generators in a composite photoimageable dry film

A method of making a three-dimensional (“3D”) structure from a composite photoresist film comprising the steps of:

• applying a first layer of photoresist material to a carrier film, the first layer containing a first photoacid generator having at least a first radiation exposure wavelength;
• drying the first layer to provide a dried first layer;
• applying a second layer of photoresist material to the dried first layer, the second layer containing a second photoacid generator having a second radiation exposure wavelength that is different from the first radiation exposure wavelength;
• drying the second layer to provide a composite photoresist material devoid of intermediate adhesion layer(s);
• applying an adhesion layer to a substrate surface;
• laminating the composite photoresist material to the adhesion layer;
• exposing the composite photoresist material to a first radiation wavelength selected from the group consisting of e-line, g-line, h-line, i-line, mid ultraviolet (UV), and deep UV radiation;
• exposing the composite photoresist material to at least a second radiation wavelength selected from the group consisting of e-line, g-line, h-line, i-line, mid ultraviolet (UV), and deep UV radiation;
• simultaneously developing the composite photoresist material to provide the 3D structure.

A fluid ejection device comprising:

• a fluid ejection head, the fluid ejection head comprising:
• a semiconductor substrate containing a plurality fluid ejection actuators on a device surface thereof and one or more fluid supply vias etched therethrough;
• an adhesion promotion layer applied to the device surface of the semiconductor substrate;
• and
• a composite photoresist material applied to the adhesion promotion layer wherein the composite photoresist material comprises (a) a first layer having a first photoacid generator therein having at least a first radiation exposure wavelength and (b) at least a second layer having a second photoacid generator therein having a second radiation exposure wavelength that is different from the first radiation exposure wavelength, and wherein the composite photoresist material is devoid of an adhesion promotion layer between layers of the composite photoresist material;
• and
• a controller for activating the fluid ejection head.