Mask aligner, Karl Süss model MJB3

Responsible: Adrian Iovan, Carlota Canalias, Anders Liljeborg

Time booking on maskaligner

Operating procedure

Careful with alignement screws!

Service: replacement of air-cylinder for mirror house movement.

Maximum mask size 100 mm (4 inch)
Maximum substrate size 63 mm (2.5 inch)




Mercury lamp

If the lamp bulb explodes...
it will fill the area around the system with toxic mercury vapour. This can cause severe neurological damage. EVACUATE THE LAB FOR AT LEAST 30 MINUTES! The maskaligner will also be seriously damaged.

Below is a typical mercury spectrum. In the mask aligner the i- h- and g-lines can be used. Currently only the g-line is used for exposure, this is optimum for S-1800 series photo-resist. To use the shorter wavelengths would give higher resolution but require the optics to be changed in the system.

Mercury lamp power supply

In constant intensity (CI) mode, the controller monitors the lamp intensity with a sensor and controls the power supply in a feedback loop to keep the intensity constant.
We always us CI2 (405 nm) because the calibrating power meter we have is for this wavelength. I = 25 mW / cm2.



Before NOW
Turn on/off complete system,
also nitrogen in service corridor
ONLY turn on/off N2 and air-switches
on the maskaligner control unit
No vacuum -> no possibility
of different exposure modes
Vacuum is available.
Possibility to select exp. modes
Height adjustment while in contact NEVER height adjustment in contact
The separation lever was never used The separation lever MUST be used
Exposures in constant power mode Exposures in constant intensity mode,
higher repeatability


Switches for compressed air and nitrogen


On/Off switch


X-, Y- and theta adjustments. Only use the outer, thinner part of the adjustment screws for X and Y.
For theta you should use the thick, main part of the screw.


The "Contact Arm" is used to lift up the stage and sample to press against the mask.
The "Contact / Separation Lever" is used to switch between close contact
or small separation between sample and mask.

Exposure modes

Mode How does it work? Resolution Comments
Vacuum Contact (HP) Vacuum is made between the mask and
the wafer prior to exposure
Standard (ST)
Hard contact mode
During exposure the vacuum holding the substrate to the chuck is switched off and positive nitrogen pressure is used to press the substrate against the mask ≅1.5 µm pitch RISK OF BREAKING THE MASK
Soft contact mode The substrate is held to the mask only by mechanical pressure of chuck throughout the exposure. The vacuum holding the substrate to the chuck remains on ≅2 µm pitch SAFE
Proximity contact Exposures are made with a small gap between the mask and substrate. The gap is determined by height adjustment Depends on separation SAFE. It has to be adjusted manually.



Splitfield Left objective Right objective
Half field of view from left obj.,
half from right obj.
Image only from left obj. Image only from right obj.
Left shutter fully clockwise
right shutter fully anti-clockwise
Left shutter halfway
right shutter fully anti-clockwise
Left shutter fully clockwise
right shutter halfway

Anders Liljeborg Nanostructure Physics, KTH.