Method of fabricating a micro-electromechanical device using organic sacrificial layers
View Patent ↗A method of fabricating a micro-electromechanical systems device that is positioned on a wafer substrate that incorporates drive circuitry includes the step of depositing a first sacrificial layer of an organic material on the wafer substrate. The first sacrificial layer is etched to define a required pattern. A layer of a conductive material is deposited on the first sacrificial layer. The layer of conductive material is etched to define a required structure and at least one subsequent sacrificial layer of organic material is deposited on the layer of conductive material. The at least one subsequent sacrificial layer is etched to define a further required pattern. A structural layer of a dielectric material is deposited on the subsequent sacrificial layer. The structural layer is etched to define a further required structure. The sacrificial layers are removed to release micro-electromechanical structures defined by the layer of conductive material and the structural layer.
1. A method of fabricating a micro-electromechanical systems device that is positioned on a wafer substrate that incorporates drive circuitry, the method comprising the steps of
depositing a first sacrificial layer of an organic material on the wafer substrate,
etching the first sacrificial layer to define a required pattern,
depositing a layer of a conductive material on the first sacrificial layer,
etching the layer of conductive material to define a required structure,
depositing at least one subsequent sacrificial layer of an organic material on the layer of conductive material,
etching said at least one subsequent sacrificial layer to define a further required pattern,
depositing a structural layer of a dielectric material on the subsequent sacrificial layer,
etching the structural layer to define a further required structure, and
removing the first and the at least one subsequent sacrificial layers to release micro-electromechanical structures defined by the layer of conductive material and the structural layer,
wherein the steps of depositing and etching the first and the at least one subsequent sacrificial layers and the conductive materials and removing the first and the at least one subsequent sacrificial layers are carried out so that the conductive material defines an actuator that is electrically connected to the drive circuitry.
2. A method as claimed in claim 1 , which further includes steps of depositing a second sacrificial layer, etching the second sacrificial layer to define said further required pattern and depositing the structural layer of the dielectric material on the second sacrificial layer.
3. A method as claimed in claim 1 , which further includes steps of depositing a second sacrificial layer on the layer of conductive material, etching the second sacrificial layer to define a required pattern, depositing a further layer of conductive material on the second sacrificial layer, etching the further layer of conductive material to define a further required structure, depositing a third layer of sacrificial material on the further layer of conductive material, etching the third layer of sacrificial material to define a required pattern, and depositing the structural material on the third layer of sacrificial material.
4. A method as claimed in claim 1 , in which the steps of depositing the first and the at least one subsequent sacrificial layers includes the step of spinning on layers of a photosensitive polyimide.
5. A method as claimed in claim 1 , in which the steps of depositing and etching the first and the at least one subsequent sacrificial layers, the conductive material and the dielectric material and removing the first and the at least one subsequent sacrificial layers are carried out so that the dielectric material defines at least part of nozzle chamber walls and a roof wall that define a nozzle chamber and an ink ejection port in fluid communication with the nozzle chamber, the actuator being operatively positioned with respect to the nozzle chamber to eject ink from the ink ejection port.