Control of cleaning performance of an ammonia and hydrogen peroxide mixture (APM) on the basis of a kinetic reaction model

Ammonia and hydrogen peroxide mixtures (APM) are widely used for removing particles from substrate surfaces in semiconductor manufacturing. In the next-generation manufacturing, more precise control of the APM cleaning performance is required than what is available today. In this study, a new method for evaluating the APM cleaning performance, such as the etching rate, surface microroughness, and particle removal efficiency, was introduced based on a chemical equilibrium analysis of APM and a kinetic reaction model of a Si substrate with APM. It became clear that the etching reaction of a Si substrate proceeds along two paths (path-1, path-2) in APM. In path-1, the Si surface is oxidized by HO₂^- and then the SiO₂ layer is etched by OH^-. In path-2, the Si surface is directly etched by OH^-. Path-1 is favorable for APM cleaning because path-2 causes some problems, such as too fast etching, an increase in surface microroughness, and a decrease in particle removal efficiency. Using the contribution ratio of each path to total etching reaction, we can predict the etching rate and determine optimum APM cleaning conditions (NH₃ concentration, H₂ O₂ concentration, temperature). This method makes it possible to improve the APM cleaning performance and to decrease chemical consumption