Appeal 2007-3417
Application 10/351,739
orientation was known, it follows that one of ordinary skill in the art would
have understood from the teachings of Aydelott that a <113> oriented single
crystal would be obtained when selecting a <113> seed crystal for use in the
Czochralski process. “The combination of familiar elements according to
known methods is likely to be obvious when it does no more than yield
predictable results.” KSR Int’l v. Teleflex Inc., 127 S. Ct. 1727, 1739, 82
USPQ2d 1385, 1395 (2007).
We also conclude that the evidence supports the Examiner’s
determination that fashioning the silicon single crystal of Aydelott with a
dash seed of at most 70 mm length would have been within the capabilities
of one of ordinary skill in the art and therefore obvious.
According to Aydelott:
Unfortunately, dislocation defects are generated in the
seed crystal due to thermal shock as the seed crystal contacts
the relatively hot melt. If corrective actions are not taken, the
dislocation defects propagate through and multiply in the
growing crystal. As known to those skilled in the art,
dislocations generally propagate along crystallographic planes.
For a silicon seed crystal having a <100> orientation, the
dislocations typically propagate along a plane that extends at an
angle of 55° from the longitudinal axis of the crystal.
In order to terminate the dislocations prior to propagation
through the main body of the crystal, crystals typically have a
neck section extending between the seed crystal and the main
body of the crystal. The most common method of eliminating
dislocations is known as the Dash method and involves growing
a neck having a relatively small diameter and a relatively long
length. For example, a neck grown according to the Dash
method may have a diameter of between 2 mm and 4 mm and a
length between 30 mm and 200 mm. As the neck is grown, the
dislocations propagate through the neck toward the interface of
the seed crystal and the melt. As a result of the extended length
5
Page: Previous 1 2 3 4 5 6 7 Next
Last modified: September 9, 2013