Method of treating wafers

A post-etch treatment method is provided which is capable of imparting high corrosion prevention performance to aluminum-containing wiring films. The sample of aluminum-containing wiring material that is etched using the halogen-type gas is treated with the plasma of a gas that has an oxygen component, and the resist formed on the aluminum-containing wiring material is reacted with oxygen and is removed. Further, a plasma is generated using a gas having a hydrogen component or this gas is liquefied into droplets thereof on the sample surface, so that halogen components (Cl, Br, etc.) adhered to the aluminum-containing wiring material through the etching treatment are reacted with hydrogen and are effectively removed in the form of hydrogen chloride (HCl) or hydrogen bromide (HBr).