(A) study on the novel heating resistors based on the composite metal-oxides for inkjet printhead

Abstract

The development of a page-wide array thermal inkjet printhead with the increased number of and array density of nozzles has recently been the focus of intensive efforts to raise printing speed and printing resolution for the application of TIJ printers. Since, however, a page-wide array thermal inkjet printhead consumes much more power to operate than conventional thermal inkjet printhead, the heat efficiency of thermal inkjet printhead should to be improved. In particular, a conventional SiN or SiC passivation layer of thermal inkjet printhead, which is used to protect underlying heating resistors, needs to be thinned or eliminated because these materials have a low thermal conductivity and act as an obstacle for heat transferring from heating resistor to ink. Up to now, several materials have been considered in the printhead, such as polysilicon, $HfB_2$, Ta-Al and TaN. In particular, TaN thin films (especially hexagonal $TaN_{0.8}$) have been known to have superior properties in fabricating accurate heater resistors for application inkjet printhead. Sputtered TaN thin films has a favorable properties such as a low TCR values, a sufficient resistivity, thermal stability, and high hardnesses. However, above mentioned heating resistor materials including $TaN_{0.8}$ cannot be used for this purpose because they are easily oxidized and corroded under the severe operation conditions such as high operation temperatures, chemical attacks by ink, and mechanical stresses arising from cavitation forces. Therefore, suitable heating resistor materials having strong antioxidation properties and anticorrosion properties, should be developed for a successful application. However, it is not easy because heating resistor materials should basically meet primary requirements such as a near zero temperature coefficient of resistance (TCR) for a stable ink ejection and a sufficient resistivity (>150 μΩ-cm) for making heating resistor of controllable thicknesses. I...