${\rm SiO}_{2}$ Etching With Aqueous HF: Design and Development of a Laboratory-Scale Integrated Wet Etch/Dry Reactor

Etching of SiO₂ films using aqueous HF-based chemistries is widely used in integrated circuit and microelectromechanical device industries. To precisely control film loss during cleaning or etching processes, good control over the contact time between the wet chemistry and the substrate is necessary. An integrated wet etch and dry reactor system has been designed and fabricated by studying various geometrical configurations using computational fluid dynamics simulations incorporating reaction kinetics from laboratory data and previously published information. The effect of various process parameters such as HF concentration, flow rate, and flow velocity on the etch rates and uniformity of thermally-grown silicon dioxide and borophosphosilicate glass films was studied. Simulations agree with experiments within experimental error. This reactor can also be used to wet etch/clean and dry other films in addition to SiO₂ based films using aggressive chemistries in addition to aqueous HF under widely different process conditions.