Rubicon has been granted its "Asymmetrical Wafer Configurations and Method for Creating the Same,” U.S. Patent No. 8,389,099 by the United States Patent and Trademark Office (USPTO).

The patent covers the creation of visual and tactile indicators to make sapphire wafers asymmetric according to their crystalline orientation.

Sapphire wafers have a specific orientation that is invisible to the naked eye.

Rubicon has developed a simple and elegant process to make wafers appear asymmetrical via visual or tactile inspection.

This is important as LED and semiconductor manufacturers process sapphire wafers using specific crystalline orientations.
Rubicon maintains this patent will help manufacturers in the LED and SoS / RFIC industries eliminate costly and unnecessary steps to determine orientation of sapphire wafers during processing, such as X-ray crystallography.

Epitaxy-ready wafers have either an orientation flat or an orientation notch, but this provides insufficient information. One problem is that the wafer could be flipped front-to-back and still look the same yet be unusable in that state crystallographically.

Only through repeated X-ray inspections could one ensure that no wafers are reversed. If the wafers are made asymmetrical, operators at each stage of production can verify surface orientation quickly and economically, and will be confident that the wafers have been handled correctly.

Rubicon’s patent demonstrates several different solutions for making sapphire wafers asymmetric.

One scenario is a rounded corner on the orientation flat or notch which allows a user to easily determine that the wafer has not been reversed. In another solution, both corners of the flat are rounded to different radii.

These differences are enough to determine orientation by touch or visual inspection. The technique can be applied to other substrates including silicon, silicon oxide, AlN, germanium, SiC, GaAs, GaP, GaN, and amorphous analogues.

“This new patent demonstrates our ongoing commitment to refine our products for our customers and deliver innovations that deliver real value,” says Raja M. Parvez, President and CEO of Rubicon Technology. “For Rubicon’s customers in the LED and SoS / RFIC markets, the crystal orientation is a critical factor in their manufacturing processes. This patent provides a simple and elegant solution to eliminating costly mistakes in the processing of sapphire wafers."

"It underscores our dedication to not only provide high quality sapphire wafers, but to provide our customers with added value to lower the total cost of LED and RF solutions,” he adds.