Experiments showed that increasing water concentration in the bath results in higher selectivity: more Si3N4 etched and less SiO2 etched. With the installations of a water concentration monitor and a water spiking apparatus, the bath is able to control the water concentration. The partial replacement of the chemical bath after each product lot reduces dissolved silicon concentration. The addition of H2SO4 saves initial conditioning time. With all of the efforts, the bath starts at a high selectivity and maintain this selectivity for an extended bath life.
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A longstanding Naura Akrion customer has purchased additional GAMA wet stations as part of a MEMS expansion. These modular GAMA wet stations incorporate the latest technological advances for process control and wafer drying, resulting in high device yield and low cost of ownership (COO).
The continuously increasing integration of today’s most advanced solar cells requires increasingly tight process control of the cell fabrication. Although numerous studies have been performed to analyze the mechanisms and kinetics of these processes, little attention, if any, has been given to monitoring and controlling the chemical concentrations in the process baths.