Patent ID: 8980009
Filing Date: 2015-03-17
Classification: B08B,G03F

Abstract:
1. A cleaning arrangement for partially removing a contamination layer from an EUV-reflective optical element defining an optical surface, the cleaning arrangement comprising: a cleaning head for directing a jet of cleaning gas to the contamination layer for removing material from the contamination layer; a monitoring unit for monitoring the contamination layer and for generating a signal indicative of the thickness of the contamination layer; a movement mechanism for moving said cleanint head relative to said optical surface; a control unit for controlling the movement of said cleaning head using said signal indicative of the thickness of the contamination layer as a feedback signal; wherein said jet of cleaning gas is controlled for removing only part of the material of the contamination layer so as to leave a distribution of the material of the contamination layer on said optical surface to have a predetermined shape.