Nodule Deformation of PVA Roller Brushes on a Rotating Plate: Optimum Cleaning for Nanosized Particles due to Liquid Absorption and Desorption of Sponge Deformation

Abstract

It is very difficult to remove extremely small particles from the surface of the wafer. Here, we proposed a new cleaning strategy using brush scrubbing, namely, nodule deformation induced fluid flow. Liquid absorption and desorption due to brush deformation enhance the mixing of liquids containing small particles. In this study, we developed a setup that reproduced the actual movement of PVA roller brushes on a rotating wafer and observed the contact surface of the brush nodule. We modeled the brush nodule deformation for each rotating condition. As a result, three types of nodule deformation were observed. In most cases, the nodule side face, rather than the bottom face was mainly in contact with the wafer surface. Moreover, we compared two types of roller brushes, normal cylindrical nodules, and edge treated nodules and found that the deformation can be significantly changed by chamfering nodule edge.

Nodule Deformation on Cleaning of PVA Roller Brushes and its Relation to Cross-contamination

“…As shown in Fig. 5, the Pr type contact is pushed in like a stamp, resulting in twisting at that point [18]. Therefore, this result suggests that the Pr type nodule contact has a strong influence on cross-contamination.…”

“…Details of this method are presented in Sanada et al [19]. Furthermore, the relative motion of a roller brush rotating on the horizontal axis on a wafer (ωW) rotating on the vertical axis (ωB) was reproduced by two servomotors; see Miyaki et al [18] for details. In this study, the relative behavior of all positions on a 100 mm wafer was visualized by changing the rotation speeds of the two motors and the contact positions of the brushes.…”

“…The superimposed technique of 20 images was used to observe the path lines of the brush nodule contact. Figure 6 shows the path line of the three deformation patterns (Fg, Rg, and Pr type) defined by Miyaki et al [18].…”

“…However, the effects of rotating both the brush and wafer have not been clarified. Besides, improving liquid mixing near the wall surface plays an important role in brush cleaning [18]. Nevertheless, the relationship between brush nodule deformation during scrubbing and liquid mixing has not been clarified.…”