0142530-000 AB
KLA-Tencor Confidential
6-41
3/13/09
KLA-Tencor P-16+ / P-6 User’s Guide Sequence Recipe and Data - Sequencing with Pattern Recognition Deskew (Optional
When choosing patterns, keep the following points in mind. (See
To set up Pattern Recognition deskew:
1.
Go to the
Sequence Editor
window.
2.
Select the sequence recipe that is to have Pattern Recog. Deskew.
3.
Select
Pattern Recog. Deskew
from the
Mode
drop-down menu. (See
Table 6.11
Pattern Search Criteria
Search Criteria
Description
Search time depends
on pattern size.
The larger the pattern, the faster the system can recognize
the pattern. However, larger patterns require more accurate
initial positioning within the camera’s field of view because the
search area is reduced.
Also, Pattern Recognition options can be set so that the
system performs a pattern search if the pattern is not found
within the field of view. See
on page 6-45 for information.
When using
rectangular pads, use
the entire rectangle.
If only two corners are used, other rectangles in the field of
view could confuse the pattern recognition system.
The pattern should be
unique and as simple
as possible.
However, uniqueness cannot be sacrificed for simplicity.
Select symmetric
patterns.
They are less sensitive to image rotation. Circular patterns
are rotationally symmetric and therefore are good patterns.
Similarly, the best polygon patterns have the most sides.
High contrast features
make pattern
recognition matches
easier.
When available, select high contrast features. Noise does not
have as much effect on the pattern recognition match. The
pattern colors are important because the pattern recognition
system reads the black and white image, not the color image.
Avoid patterns with
rough surfaces.
By using edge enhancement, the instrument computer
emphasizes the fine features present on a rough surface.
Because roughness is random, these features add noise to
the system and make the pattern recognition system less
reliable.
NOTE:
It is generally a good idea to avoid fixed dust particles in the
field of view as well. Avoid selecting wafer-specific defects or features
as patterns, or the instrument computer could become confused. This
includes dust particles, partially etched areas near the edge of the
wafer, and so on.