Operation of the Machine
MA6 / MA8 - 1. Operation of the Machine - Rev.05 07-06
27
1
break the vacuum. The larger the wafer the longer the
vacuum and purge times. For best results start a test
with long times and reduce them gradually. All the pa
-
rameter could be set using the EDIT PARAMETER
key (311).
Low Vacuum Contact Exposure
This mode is similar to vacuum contact with one dif-
ference: The vacuum level in the wafer chamber can
be adjusted by the LOW VACUUM ADJUSTMENT
regulator (205). So the high resolution level of the vac
-
uum contact exposure can be combined with a min-
imum mechanical stress for wafer and mask. Set an
appropriate vacuum with the vacuum chamber regu
-
lator (205) and test the result using the ALIGNMENT
CHECK key (305).
Flood Exposure
It is possible to exposure the whole wafer without a
mask. After this mode is selected, the exposure can
be started from the initial state by pressing the EXPO
-
SURE key (316). The exposure takes place as long as
the exposure time was set independent if a mask
(and mask holder) is loaded or not.
1.4.2 Multiple Exposure
For special applications the numerical value for the
overall exposure time can be segmented into equal
exposure intervals alternating with wait time intervals
in which the wafer is not exposed. One exposure time
and one wait time is named as one exposure cycle.
To perform Multiple Exposure proceed as follows:
– Select the corresponding exposure program by
the SELECT PROGRAM key (310).
– Press the Multiple Exposure key (317).
– Press the EDIT PARAMETER key (311).
– Edit the parameter for the exposure program. Edit
the numerical value of the corresponding param
-
eters wait time and cycles.
– Press the flashing EDIT PARAMETER key to finish
editing and start alignment followed by the multi
-
ple exposure process.
1.4.3 Wedge Error Compensation
During this procedure the top side of the wafer will be
set exactly parallel to the bottom side of the mask.
This guarantees a perfect gap setting and so a homo
-
geneous quality of the exposed structures over the
whole wafer. Set the WEC type using the EDIT PA
-
RAMETER key (311).
Two methods are standard:
– contact mode:
For the exact parallel setting the wafer will be
moved against the mask.
– spacer mode:
To treat mask and wafer with maximum care the
machine moves spacers in between both. A prox
-
imity mask holder is necessary. Contact area is re-
duced to three points near the wafer edge.
Additionally two other methods are also possible.
Global WEC between mask and chuck. This could be
used for pieces or other special applications. It is
mandatory to set the thickness of a substrate or wa
-
fer accordingly before WEC procedure is initiated.
– global WEC contact mode:
The WEC will be performed between wafer chuck
and mask without the wafer (GlobCont). Before
alignment set the wafer thickness. Another pa
-
rameter of the EDIT PARAMETER menu is listed.
It is the substrate thickness.
– global WEC spacer mode:
The WEC will be performed between wafer chuck
and mask using spacers in between (GlobSpac).
Depending of the spacer and substrate dimen
-
sions it's enabled to perform this with a loaded
substrate. Before alignment set the wafer thick
-
ness using the EDIT PARAMETER menu.
1.4.4 Load Mask by Slide
Additional to the manual mask loading (described in
the operating procedures, Chapter 3.3.3, Load
mask) this method is available. Mask and mask hold
-
er must not be flipped 180°. The active side of the
mask is never face up. A standard mask holder and
mask loading chuck are necessary. Working with this
loading sequence prealignment pins and mechanical
mask clamping has to be removed from the mask
holder. Load the mask holder in the stage and clamp
it. insert the mask transfer chuck in the transport slide
and place the mask face down on it. Fix it by toggle
the vacuum on. Move transport slide in the machine
and confirm. Now there are two possibilities depend
-
ing of the prior selection (by F1 key):
– without alignment
The machine moves the mask against mask hold-
er. After the vacuum sensor detect that the mask
holder vacuum take in the mask, the transport
slide vacuum switches off. Transport slide moves
down.
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