Patent ID: 8043521

Claim:
A processing method for performing wet etching in a processing system to process stacked films, which comprise a first film and a second film below the first film, present on a target object, the processing system comprising a housing section configured to house the target object, a first process liquid supply section configured to supply a first process liquid into the housing section, the first process liquid being capable of etching the first film with a higher etching selectively relative to the second film, a second process liquid supply section configured to supply a second process liquid into the housing section, the second process liquid being capable of etching the second film with a higher etching selectively relative to the first film, a detecting section configured to measure concentration of a prescribed substance contained in liquid discharged from the housing section, a switching section configured to switch between the first process liquid and the second process liquid to supply one of the first and second process liquids into the housing section, and a control section configured to control a certain operation of the system, the processing method being conducted by the control section and comprising: performing a first etching on the target object, while supplying the first process liquid from the first process liquid supply section into the housing section that houses the target object; detecting by the detecting section the concentration of the prescribed substance contained in the first process liquid discharged from the housing section in the first etching, the prescribed substance being a component of a least one of the first film and the second film; performing by the control section a judgment of whether the first film has been removed, based on the amount of the component of at least one of the first film and the second film contained in the first process liquid being used for the first etching, the amount of the component being obtained from a value of the concentration thus detected by the detecting section; and in response to a determination that the first film has been removed, switching the process liquid to be supplied into the housing section from the first process liquid to the second process liquid, and performing a second etching on the target object, while supplying the second process liquid from the second process liquid supply section into the housing section that houses the target object, wherein the first film is a hafnium oxide film and the second film is a silicon oxide film, and the first and second process liquids respectively consist of dilute hydrofluoric acid liquids prepared by diluting hydrofluoric acid with water, which are mixed or not mixed with ethanol such that the first process liquid has a first ethanol concentration and the second process liquid has a second ethanol concentration lower than the first ethanol concentration.