Patent ID: 8080113

Claim:
A Method for collecting impurities from the surface of a semiconductor wafer in which impurities are removed from the wafer's surface by moving a liquid drop relative to the surface of the wafer so as to dissolve impurities into the liquid drop, the method comprising: forming a liquid drop on the surface of the wafer; holding the liquid drop with a liquid drop holder that can move the drop across the surface of the wafer; a first scanning step of positioning the liquid drop holder at a radial position where the liquid drop can contact a boundary region bordering a chamfered part, on a front plane flat part of the semiconductor wafer, and scanning in the circumference direction; a first collecting step of collecting the liquid drop that includes dissolved impurities that were removed from the front plane flat part of the semiconductor wafer: a second scanning step of positioning the liquid drop holder at a position where a liquid drop held by the liquid drop holder can contact both the chamfered part and the boundary region of the semiconductor wafer, and scanning in the circumference direction so that impurities on the chamfered part can be dissolved into the held liquid drop; and a second collecting step of collecting the drop that includes dissolved impurities that were removed from the chamfered part of the semiconductor wafer, said second collecting step being separate from said first collecting step.