Mask cleaning strategies: particle elimination with minimal surface damage

Cleaning becomes increasing important and challenging as feature sizes continue to shrink. Many methods and strategies have been explored to reduce particle defects and ion haze that destroy yield on pelliclized reticles. A successful cleaning method must balance reductions of particles and haze while imposing minimal changes to the transmissivity of the chrome stack, to exposed quartz and to the phase shift of molybdenum silicide surfaces. This paper focuses on the inclusion of many previously explored cleaning methods working in concert within a single reticle cleaning tool. We present our findings on elimination of particles with minimum impact on reflectivity and phase angle. We test the collective effects of Ozonated Water (O3W) and final cleaning methods that employ ammonia hydroxide and hydrogen water. These methods are presented within the context of spin cleaning applications.