Sequence Recipe and Data - Sequencing with Pattern Recognition Deskew (Optional Pattern Recognition Feature, P-16+
6-40 KLA-Tencor Confidential 0142530-000 AB
3/13/09
A pattern recognition deskew site is a unique pattern of wafer features visible within
the instrument’s field of view. The size and shape of the pattern must be uniquely
different from other wafer features visible in the field of view to ensure that the
instrument can locate the sites without ambiguity. (See Table 6.10).
NOTE: To minimize positioning error, space the deskew points at least
one-half the diameter of the sample. It is recommended to not set the
deskew points parallel to the X-axis or Y-axis, but instead use two
points on a diagonal line. If the deskew points are identical, the
sequence aborts.
NOTE: Although a coordinate transformation is made, there is no
stage rotation to compensate for the small rotational error in sample
placement unless the deskew option is set to perform a second
deskew. See Deskewing Twice To Align Theta (P-16+ only)
on page 6-39 for more information.
NOTE: Note also that any rotational error is magnified when
traversing a long distance across a large wafer. This might cause the
deskew site to be outside the field of view when a wafer is loaded.
Table 6.10 Pattern Examples
Pattern Example Description
Good Patterns
Alphanumeric characters
Rectangular pads that appear singly
Crosses
Alignment marks
Other polygon shapes
Bad Patterns
Sections of a repetitive grid
Circular pads or rectangular pads that repeat in or near the
field of view
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