Semiconductor processing preclean methods and apparatus

In some embodiments, a method for semiconductor processing preclean includes removing an oxide layer from a substrate using anhydrous hydrogen fluoride in combination with water vapor. A system for the preclean may be configured to separate the anhydrous hydrogen fluoride and the water vapor until they are delivered to a common volume near the substrate. Corrosion within components of the system may be limited by purification of anhydrous hydrogen fluoride, passivation of components, changing component materials, and heating components. Passivation may be achieved by filling a gas delivery component with anhydrous hydrogen fluoride and allowing the anhydrous hydrogen fluoride to remain in the gas delivery component to form a passivation layer. Consistent water vapor delivery may be achieved in part by heating components using heaters.