Non-contact wafer handling using high-intensity ultrasonics

Increasing requirements placed on the handling of parts in semiconductor fabrication necessitate the development of new innovative methods to handle wafers as fragile and surface-sensitive substrates. In order to avoid the inherent disadvantages of tactile handling, it makes sense to manipulate wafers or substrates without physical contact. This is where the technology of acoustic levitation offers itself as a suitable approach. Basically, two physical effects can be utilized: while work pieces can be positioned and manipulated within a standing wave pattern, the application of the principle of near field levitation also makes it possible to design nontactile handling systems, both of which are presented in this paper.