Cast cylindrical poly vinyl acetate (PVA) brushes are conventionally used in automatic cleaning systems to provide a post CMP (Chemical Mechanical Planarization) process to effectively clean surfaces of substrates such as semiconductor wafers or other disc-shaped substrates. PVA brushes are also used in cleaning systems to clean and dry glass and other non-disc-shaped substrates in flat panel display manufacture, glass production, and printed circuit board assembly. Brushes may have a length as short as 50 millimeters or as long as 10 meters, for example. The brushes extend completely across the substrate being treated, thereby contacting the substrate an entire distance across its diameter. The brushes are located on and driven by a central mandrel about a central longitudinal axis in the cleaning process. The brushes have nodules on their outer surface to help clean the substrate as shown in FIG. 1.
Conventional nodule PVA brushes rely on indiscriminate excitation to remove particles from semiconductor surfaces/substrates. The particles can be removed by lifting from the semiconductor surface/substrate, sliding over the semiconductor surface/substrate, or rolling on the semiconductor surface/substrate, as shown for example in FIG. 2. In FIG. 2, the nodules are shown by the small ovals, some of which are labeled with reference number 10, and the particles are shown by reference number 12. The hydrodynamic and/or electro-kinetic forces associated with conventional nodule PVA brushes do not move particles with any directionality off of the semiconductor surface/substrate to be cleaned. Because the center of a rotating semiconductor surface/substrate relies primarily on the forces exerted by the brush to remove particles, particle re-deposition is common and cleaning the center of the semiconductor surface/substrate is challenging. This problem is exacerbated with the transition to larger semiconductor surfaces/substrates (e.g. 300 mm to 450 mm).