Contactless Positioning using an Active Air Film

Contactless Positioning using an Active Air Film

Wesselingh, J.

Van Eijk, J. (promotor)
Spronck, J.W. (promotor)

Mechanical, Maritime and Materials Engineering

Precision and Microsystems Engineering

2011-11-18

In the production of integrated circuits, solar cells, flat panel displays and elec- tronics, thin plates are often used as a base for manufacturing. Examples are silicon wafers and glass panels on which several process steps build transistors, pixels and interconnects. To improve the production throughput these features are made smaller while the substrates are made bigger. The result is that the manufacturing equipment has to perform its process with increasing precision to ensure functionality of the end product. In addition, as the substrate size increases these plates become more fragile. A possible solution for the manufacturing equipment which requires these precise positioning and alignment tasks is to use a thin gas film on which the substrate floats. This thesis discusses the possibilities using such an air film principle in a positioning system. Pressurised air is used to provide the bearing functionality while the air flow generated is also used to drive the substrate. Both this bearing and motor function are realised in a single unit, the so-called actuator. To come to a complete positioning system, the position of the plate is measured using sensors and fed back to the actuator using a controller. The main advantage of such a system is that only the substrate itself is driven. In similar positioning systems, an additional carrier is often used on which the substrate is placed. This carrier is often several times heavier than the substrate itself. As a result the forces required for accelerating increase significantly. In precision system this leads to several unwanted effects such as frame deformation, excitation of structural resonances and an increased heat load from the power dissipation. An additional advantage to eliminating the carrier is that the fragile substrate is only in contact with the air film. With a carrier a mechanical contact is introduced where friction can occur. This in turn can cause damage to the substrate or can result in particles which can contaminate the production process.

contactless
positioning
air film
air bearing
control
servo
high precision

http://resolver.tudelft.nl/uuid:4f90d3b0-1698-4885-b4b4-bdec9d886893

2011-11-18

9789090264370

Institutional Repository

doctoral thesis

(c) 2011 Wesselingh, J.