The Transition to Optical Wafer Flatness Metrology

As optical lithography requirements drive wafer flatness toward increasing levels of perfection, the industry is faced with a need to transition from current standard practice. In this paper we present a historical perspective on starting material dimensional metrology, leading to the current standard for wafer manufacturing quality control, capacitance‐based wafer flatness metrology. We then investigate the market and technical factors that compel a transition to optical flatness metrology. Comparative data (from advanced 300mm wafers) between capacitive and optical flatness measurement tools permits us to conclude that the industry transition to optical dimensional metrology can occur without disruption of accepted manufacturing baselines.