Development of an Air-Based Contactless Transport Demonstrator

Abstract

In many industries, for example the semi-conductor and solar cell industry, production processes have to handle thin substrates such as wafers or solar cells. For economic reasons, the thickness of these substrates shows a decreasing trend over the years. This results in an increasing breakage rate of the substrates during the production process. A solution to this problem could be air-based contactless handling. A thin film of air is used to perform a levitation and propulsion function. The levitation is similar to conventional air bearing technology, while the propulsion is achieved by exploiting the viscous traction force of a thin film of air. The state of the art in contactless positioning using a thin film of air is mainly focused on the positioning of the substrate. The next step in thin substrate handling is transporting them.
In this project, a transport demonstrator for handling a 100 mm diameter wafer is designed and fabricated. This is done in a layer approached way, for which new manufacturing methods are developed. The demonstrator consists of an active surface and a passive surface. The active air bearing surface is able to actuate and levitate the wafer in two degrees of freedom, while the passive air bearing surface is only able to levitate the wafer and guide its motion. Crucial in the combination of the two different surfaces is a smooth transition of the wafer. This is realised by matching the wafer fly height and the air film stiffness of each surface. A smooth transition of the wafer between the active surface and the passive surface is observed. Therefore, the demonstrator is a promising concept to realise an air-based contactless conveying line for thin substrates.