New Way Issued Patent for Air Bar Concept

New Way^® Air Bearings Issued Patent for Air Bar Concept.

United States Patent No. 7,908,885-B2 Covers a Porous Media Air Bearing and Glass Flattening Device for Non-Contact Glass-Handling Applications.

Aston, Pennsylvania, USA – June 30, 2011 – New Way^® Air Bearings, the world’s largest independent manufacturer of porous media air bearing products, announced that it has been issued United States Patent No. 7,908,885-B2 for its ‘Non-Contact Porous Air Bearing and Glass Flattening Device.’

According to the patent, this invention is directed to a system and method for supporting thin work pieces, particularly glass, for more precise inspection, coating, patterning, and other processes without contacting the work piece.

The common technique with semiconductors was to put the substrate on a vacuum chuck. This is also how the Flat Panel Display (FPD) industry started out. But as FPD glass substrates grew larger – about Generation 6 – this technology became impractical. In the chuck method there were two primary flatness error sources: 1) The flatness of the chucks supporting the glass, including any contamination between chuck and glass, and 2) the thickness of the glass itself.

By floating the glass through a precision zone, the area that requires precision is dramatically reduced from the area of the entire vacuum chuck to the area directly under the process.

New Way Air Bearings was the pioneer in the development of non-contact glass handling components for processing and inspection, with commercial sales in Japan as early as 1999. Throughout the next decade, New Way honed its technology leadership with the release of new products enabling substrate stability to ±1 nanometer.

But the error of the thickness variation remained.

“Even high-quality Flat Panel Display (FPD) glass is subject to thickness variations, reducing processing and inspection accuracy,” noted New Way chairman and CTO Drew Devitt, who is also credited as the inventor of this New Way patent. “But this new technology stands conventional thinking on its head. It uses a combination of air pressure and vacuum from above to control and flatten the glass substrate, enabling a much higher degree of processing accuracy, all without contact.”

FPD glass has an inherent thickness variation of 5 to 7 microns; when it is sucked down to a flat vacuum chuck, all 5 to 7 microns of this variation will appear as surface-flatness error. By positioning the vacuum preloaded air bearing array on the same side as the precision process being applied to the glass, the natural thickness errors in the glass or substrate may be removed or minimized.

New Way utilizes its porous media air bearing technology to evenly distribute air pressure through millions of sub-micron sized holes across the air bar surface with the capacity to carry thousands of kilograms of load. Simultaneously, a set of vacuum holes and grooves provide tens of kilograms of atmospheric force, which evenly pushes and flattens the glass up against the air film, and holds it in a very ‘safe place.’ The result is a non-contact precision zone which presents the flattest possible glass surface to the process.

Glass thickness variation errors have started to become a limiting factor for the higher-resolution types of lithography required for higher definition displays. This new approach reduces the requirement for depth-of-field capability in the tool, and enables higher-resolution lithography, while also greatly minimizing the structural loop between the optics and the glass.

This technique also allows for:

• Viscous shear cleaning* of the surface immediately before the process,
• Isolation of process gases* or containment of particulates from ablation processes, and
• Glass conditioning* with relation to temperature, humidity, and oxygen levels in the bonding layer pre-coating.

*Which are protected by separate patents.

Today’s Generation 10 glass is 2850mm x 3050mm, or 8.7 square meters. And a structural loop which must include components above and below the glass is problematic.

“The second significant advantage of our new patent is the reduction in size of the overall structural loop,” Devitt continued. “Many contemporary FPD processing lines still feature a multi-ton granite base, a giant gantry with two large granite columns, a huge stage mechanism, and the processing equipment or inspection cameras themselves. This structural loop can be 10 meters or longer.”

“In this new embodiment, with the glass moving just 10 microns below the processing or inspection equipment, the structural loop can be just a small fraction of a meter. This avoids errors from thermal and vibration sources in the machine.”