wafer stress metrology is unique in our industry. The technology
is based on several Ultratech patents for the coherent gradient sensing
(CGS) of wafer topography and stress. The interferometric technology
was originally developed by a small team of researchers, working
under the business name "Oraxion". In July, 2006, Ultratech,
Inc. acquired certain assets of Oraxion.
The team brought to Ultratech the unique ability to measure the stresses induced
by laser thermal processing -- a capability not available elsewhere in the industry.
Low stress levels are inherently difficult to measure, however by the use of
CGS, the Ultratech engineers are able to study and analyze the very low level
effects of laser thermal processing.
While both new and unique, this technology has been heavily and successfully
applied to practical customer situations. More than 120,000 wafers have been
measured using this method, of which more than 20,000 have been measured in Ultratech's
own process laboratory. This practical data has led to a deep understanding of
the annealing process and optimum means of reducing stress -- unparalleled elsewhere
in the industry.