HEIDELBERG mPG 501, Руководство пользователя

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µPG 501
14
User Guide
STEPS OF AN EXPOSURE WITH ALIGNMENT
Alignment is done to expose a design in a defined position with respect to marks on the
substrate. The coordinates of a clearly defined point within a mark (e.g., a corner) are
used as anchor(s) for the coordinate system. Depending on the number of marks,
different levels of accuracy can be reached:
•
one point alignment
: If only one mark is used for alignment, only the origin is
shifted to match the origin of the existing pattern.
•
multiple point alignment
:
Using 2 – 4 marks allow for a rotational adjustment of the
design to the existing pattern. If this is used, the pattern is
re-converted with the angle that has been found. A 3
rd
and
4
th
mark increase accuracy though more averaging.
Several different alignment methods are available in the wizard, a manual method and
three automatic methods:
•
manual alignment
: The operator has to indicate the points that have the known
coordinates
•
template matching
: An image template of the alignment mark is defined, and the
design coordinates are assigned to the position where this
template is found. This is useful if either a substrate has
several identical marks, or the same marks are used on
several substrates.
A template does not have to contain a complete structure.
Often, it is more useful to use e.g., one corner of a structure,
as this gives a defined point for the template center position
and the coordinates that are assigned to it. No similar
feature may be close by, and the feature should be small
enough that the template box is still within the image field
even if the structure is displaced a bit.
•
cross alignment
This is the most precise method of alignment. One or more
crosses are used for position and angle detection. The cross
should have arms that are significantly longer than wide. For
good results, the size should be at least so that it covers half
the image field. Best results are obtained with sizes that are
larger than the image field.
•
mask edge
Detects position and angle of the mask edges using the
autofocus system, and calculates center position and
rotation from that (rectangular samples only).