Fluid ejection microfluidic device, in particular for ink printing, and manufacturing process thereof

A process for manufacturing a fluid ejection microfluidic device, comprising:

• forming, in a first substrate of semiconductor material having a first main surface and a second main surface, an enclosed buried cavity delimiting a membrane between the enclosed buried cavity and the first main surface of the first substrate;
• forming a sealed actuation structure on the membrane;
• forming an access channel extending between the first and second main surfaces of the first substrate, in a lateral position that is external to the enclosed buried cavity and to the membrane;
• forming, on the first main surface of the first substrate, a containment layer, of polymeric material, laterally delimiting a fluid containment chamber surrounding the sealed actuation structure;
• bonding a nozzle body of semiconductor material to the containment layer and closing the fluid containment chamber at the top;
• and
• forming an ejection opening extending through the nozzle body, the ejection opening facing and being in fluidic communication with the fluid containment chamber to form a fluidic path together with the fluid containment chamber and the access channel.

A printing head comprising:

• a microprocessor;
• and
• a fluid ejection microfluidic device coupled to the microprocessor, the fluid ejection microfluidic device comprising:
• a substrate of semiconductor material;
• an enclosed buried cavity within the substrate;
• a membrane formed in the substrate and delimited by the enclosed buried cavity and the first main surface;
• an access channel extending through the substrate, wherein the access channel is fluidically isolated from the enclosed buried cavity;
• an actuator coupled to the membrane;
• a layer of polymeric material coupled to the substrate and forming a chamber;
• a nozzle body of semiconductor material coupled to the layer of polymeric material and covering the chamber;
• a fluid containment chamber delimited at least in part by the layer of polymeric material and the nozzle body, wherein the fluid containment chamber is fluidically coupled to the access channel, wherein the actuator is located in the fluid containment chamber;
• and
• an ejection opening in the nozzle body, the ejection opening fluidically coupled to the fluid containment chamber and forming a fluidic path with the fluid containment chamber and the access channel.