Optical performance of laser light source for ArF immersion double patterning lithography tool

In advanced lithography processes, immersion lithography technology is beginning to be used in volume production at the 45-nm technology node. Beyond that, double-patterning immersion lithography is considered to be one of the promising technologies -meeting the requirements of the next-generation 32-nm technology node. Light source requirements for double patterning lithography tool are high power and high uptime to enhance economic efficiency, as well as extremely stable optical performances for high resolution capabilities. In this paper, the GT62A, Argon Fluoride (ArF) excimer laser light source which meets these requirements is introduced. The GT62A has an emission wavelength of 193-nm, a power output of 90 W and a repetition rate of 6,000 Hz. The dose uniformity of the GT62A was improved for reduction of Critical Dimension (CD) variation and better Critical Dimension Uniformity (CDU). A stable wavelength and a spectrum bandwidth of the GT62A satisfy the requirements of the high resolution lithography tools which need the steady focus stability. In addition, we verified by simulation that the spectrum bandwidth control in the GT62A contributes to Depth of Focus (DOF) enhancement. The new technology for the light source and detailed optical performance data are presented.