Ink jet printhead having integral filter

摘要

An ink jet printhead having an integral membrane filter fabricated over the surface of the printhead containing the ink inlet is disclosed. The individual printheads are obtained by a sectioning operation which cuts aligned and bonded channel and heater wafers. The mated wafers contain a plurality of printheads and must be separated. The integral membrane filter is formed on the channel wafer after it is anisotropically etched incorporating the etch resistant mask layer and prior to mating with the heater wafer. A patternable layer is deposited over the etch resistant masking layer and exposed, patterned and developed to establish the mesh filter. In one embodiment, the side of the channel wafer not patterned and etched is heavily doped to form an etch stop which increases the robustness of the membrane filter by ensuring that the masking layer remains intact during subsequent fabricating steps. This doped region beneath the patternable layer is then etched using the membrane filter as a mask to open the filter pores through the doped layer of the channel wafer, thereby increasing the filter thickness and its overall strength.