Apparatus for on-line cleaning a wafer chuck with laser

A wafer exposure system with a built-in wafer chuck laser cleaning apparatus, the wafer exposure system comprising:

• a wafer stage capable of horizontally or vertically moving;
• a wafer chuck, for holding a wafer-to-be-exposed by vacuuming, fixed on the wafer stage;
• a laser power supply for providing a pulse laser;
• a projection lens module located over the wafer chuck;
• a focus lens module located at one side of the projection lens module;
• a steering mirror module used to selectively guide the pulse laser to the projection lens module or the focus lens module;
• a flow chamber module, fixed on one end of the focus lens module, used to isolate the wafer chuck during wafer chuck cleaning;
• and
• an inert gas supply, connected with the flow chamber module, used to produce a laminar flow of inert gas;
• wherein in a wafer chuck cleaning phase, the wafer stage moves under the focus lens module, the flow chamber module moves downward and covers the wafer chuck in a hermetically sealing manner, the pulse laser is guided to the contaminated top surface through the focus lens module;
• after the wafer chuck cleaning phase, the wafer stage returns under the projection lens module, a loading arm loads a wafer onto the cleaned wafer chuck, and the wafer is exposed by the pulse laser guided through the projection lens module.

A stepper system having an on-line wafer chuck laser cleaning apparatus, the stepper system comprising:

• an excimer laser generation module for generating a pulse laser with a predetermined wavelength;
• a wafer stage capable of horizontally moving along x-y directions vertically moving along z direction;
• a control system used to control displacements of the wafer stage along the x-y directions and the z direction;
• a wafer chuck, for holding a wafer-to-be-exposed by vacuuming, fixed on the wafer stage, the wafer chuck having a top surface capable of being contaminated by organic material;
• a laser beam delivery system for guiding the pulse laser to a contaminated top surface of the wafer chuck at a predetermined incident angle, and decomposing organic material thereon by the pulse laser;
• a projection lens system for focusing the pulse laser to the wafer-to-be-exposed;
• a laminar flow chamber located at one end of the laser beam delivery system and used to isolate the wafer chuck during the wafer chuck cleaning, the laminar flow chamber having an opening at a bottom, a gas inlet, and an exhaust, a casing of the laminar flow chamber being connected with the laser beam delivery system via a flexible joint that enables the laminar flow chamber to move downward and upward to generate a hermetically-sealed region within the laminar flow chamber after moving downward and contacting the wafer stage;
• and
• an inert gas supply connected with the gas inlet of the laminar flow chamber for providing an inert gas flow, wherein the inert gas flow is in a laminar regime within the laminar flow chamber facilitating the removal of the decomposed organic material from the top surface of the wafer chuck;
• wherein the organic matter contaminated top surface of the wafer chuck is globally or locally cleaned by the control of the control system-controlled wafer stage.