Immersion-cluster uptime enhancement technology toward high-volume manufacturing

In immersion lithography, importance is placed on technology for controlling coating along the edge of the wafer. In the case of a top-coat process, it has been observed that the top coat can peel off during immersion exposure due to weak adhesion to the substrate, a characteristic of top-coat films. The peeling of the film is thought to adversely affect immersion-exposure equipment and the wafer surface by the formation of defects due to the contamination of the immersion-exposure tool and by residual particles. Nikon Corporation and Tokyo Electron Ltd. (TEL) have performed joint research and development in response to these problems. TEL has studied rinsing technology for the wafer edge section and established coating processes and control techniques that rinse the edge section to remove foreign matter and that control the cutting position of each film in the edge section. TEL has developed new processes and hardware to remove foreign matter introduced into the immersion-exposure tool, and has shown that this technology can help prevent contamination of exposure equipment. Nikon has established efficient on-body periodic rinsing as a new technology for exposure equipment that can reduce defect.