Wafer cleaning using a laser and carbon dioxide snow

Abstract

Apparatus and methods for removing particles from a surface of a semiconductor wafer or optical component using a carbon dioxide snow spray directed at the wafer or component while simultaneously irradiating the surface with a laser beam. The apparatus comprises a carbon dioxide jet spray cleaning system disposed within an environmental cleaning station of a processing system that processes the wafer or component. The processing system is a conveyorized system wherein a conveyor belt or web transports wafers or components from processing station to processing station. The cleaning station includes a recirculating blower system, a laminar flow screen, a high efficiency particulate air filter, and a ducting system for recirculating purified air or inert gas. The cleaning station contains a jet spray nozzle that produces a carbon dioxide snow spray. The jet spray nozzle is coupled by way of a manifold to a liquid carbon dioxide tank that supplies liquid carbon dioxide to the jet spray nozzle. The wafer or component is grounded to prevent static charge buildup. A carbon dioxide laser, operating at 10.6 microns, produces a laser beam that is generally aligned with the carbon dioxide snow spray so that the beam and spray overlap. The laser beam heats the surface of the wafer or component to compensate for the cooling effects of the carbon dioxide snow.