Physical chemistry of water droplets in wafer cleaning with low water use

摘要

A new method for cleaning wafers with low use of water and mechanical action is under investigation. The method is based on moving a droplet over a wafer surface. Particles are removed by the surface tension of the water. This method should be capable of removing nano-particles without using excessive mechanical action. One of the important factors is the ability to manipulate the droplet. This requires a finite contact angle between the droplet and the wafer. The discrete contact angle must be especially present at the receding end of the droplet in order to prevent pearling. Even at the higher speeds needed for realization of a sufficiently short process time. In the experiments it was shown that the pearling limit was strongly dependent on the wafer type. With the help of a simple additive velocities up to 80 mm/s could be achieved without pearling. The results show that the method of moving a water droplet over the wafer is feasible and steps to develop the method into a wafer sized cleaning unit can proceed.