SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 1/14
MO Exposure Optics: IFP - Guide
General Remarks The Illumination Filter Plates (IFPs) are responsible for the creation of defined illumination
angles at the mask plane. The shape of the aperture is transformed into an angular
distribution of the light at the mask plane.
Example D-IFP:
Inserted into the MO
Exposure Optics the light
on the mask plane comes
from seven directions
The D-IFP is a metal
aperture with 7 holes
Every point on the mask plane is hit
by an identical angular light
distribution and intensity.
The angular distribution affects the resist image. Therefore it
can be optimized for every process. Process parameters as
resist-type, resist thickness, structure shapes and structure
sizes and proximity gap have a major impact on the resist-
image formation and have to be taken into account. Due to
this it is just possible to give some advices for the choice of
the right IFP for a process.
General rules for the right choice of IFPs 1. The IFP should be chosen for the most important process parameter: Different
shapes can improve different aspects of your lithography result. If there are
different structures on the mask but just a certain structure is critical for the
function of your device, you should choose an IFP to improve this certain structure.
If different shapes of structures on the mask are important for the function of the
device and critical to transfer into the resist, a more universal solution as the HR-IFPs
or a circle fitting to your gap should be chosen.
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
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2. Bigger openings can decrease diffraction effects: If diffraction effects have a bad
influence on the resist images (e.g. side lobes) such effects may be minimized by
using an IFP with a big opening.
3. Small openings can improve resist images for big gaps and resist steepness: To
receive proper lithography results using bigger proximity gaps (>100 µm) you need
to have small illumination angles, thus small openings of the IFPs. In the most cases
the shape of structures and the sidewall steepness can be increased with decreasing
opening sizes.
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 3/14
IFP Design Description Page
HR – A - IFP 4
LGO - IFP 5
Medium Circle - IFP 6
Big Circle - IFP 7
D – IFP 8
Quadrupole – IFP 9
Quadrupole-45°-IFP 10
Small Ring – IFP 11
Big Ring – IFP 12
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 4/14
Description:
HR – A - IFP
Recommended gap range: Recommended application:
Contact – 50 µm Replacement of classic “HR-A-Optics”
Remark:
The IFP creates illumination angles equal to the SUSS High Resolution Optics (HR-Optics) in
the so called A-Configuration (12 Lenses in triangular alignment). Therefore this IFP is the
best choice for working processes that were running with an A - Optics before an MO
Exposure Optics upgrade. In general the HR - IFPs, as the classic HR-A - Optics, is a good
choice for relatively small gaps and various structure shapes and sizes on one mask.
Example:
Simulation 2 µm AZ1518
30 µm proximity gap
3 µm lines and spaces
Mask pattern LGO-IFP HR-A-IFP HR-A-Optics
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 5/14
Description:
LGO - IFP
Recommended gap range: Recommended application:
> 80 µm Big Gaps / Replacement of LGO-Optics /
Steeper sidewalls Remark:
The LGO - IFP is designed to improve lithography results for big gaps. Compared to IFPs with
bigger openings it can allow to print structures down to the physical resolution limit for
larger gaps and increase wall steepness for standard DNQ positive resists. At smaller gaps
diffraction effects can appear more strongly using this IFP compared with IFPs with a bigger
opening.
Example:
Simulation 2 µm AZ1518
100 µm proximity gap
7 µm squares (2D-periodic)
Mask pattern HR – A - IFP LGO - IFP
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 6/14
Description:
Medium Circle - IFP
Recommended gap range: Recommended application:
50 µm -150 µm Compromise for throughput at medium to
big gaps Remark:
The LGO IFP will in the most cases provide the best results for big gaps. The bigger opening
of the Medium Circle – IFP compared to the LGO - IFP causes a higher intensity and
therefore shorter exposure times with slightly less effect on the sidewalls than the LGO - IFP.
Example:
Simulation 2 µm AZ1518
100 µm proximity gap
8 µm lines and spaces (2D-periodic)
Mask Pattern HR – A - IFP Medium Circle - IFP
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 7/14
Description:
Big Circle - IFP
Recommended gap range: Recommended application:
Contact – 50 µm Maximum throughput for uncritical layers
Remark:
The big aperture leads to the highest intensity of all IFPs and therefore the highest
throughput. In the recommended gap range the IFP decreases diffraction effects as side
lobes. Caused by the bigger illumination angles it can cause worse results than other IFPs
(e.g. sidewall steepness, image quality), especially for thick resists and big proximity gaps.
Example:
Simulation 2 µm AZ1518
50 µm proximity gap
5.5 µm lines and spaces (2D-periodic)
Mask Pattern LGO- IFP Big Circle IFP
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 8/14
Description:
D – IFP
Recommended gap range: Recommended application:
Contact – 50 µm Replacement of classic “D-Optics”
Remark:
The IFP creates illumination angles equal to the SUSS Optics in the so called D - Configuration
(7 Lenses in hexagonal alignment). Therefor this IFP is the best choice for well-established
lithography steps that were running with a D - Optics before a MO Exposure Optics upgrade.
In general the HR-IFP, as the classic HR – A - Optics, is a good choice for relatively small gaps
and various structures shapes and sizes on one mask.
Example:
Simulation 2 µm AZ1518
30 µm proximity gap
3 µm lines and spaces
Mask pattern LGO-IFP HR-D-Optics HR-D-IFP
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 9/14
Description:
Quadrupole – IFP
Recommended gap range: Recommended application:
50 µm - 100 µm Squared structures and corners
Remark:
The Quadrupole - IFP is designed for structures with a quadratic shape or in a quadratic
arrangement. Depending on the gap and on the specific structures it can work for
orthogonal structures parallel to the mask grid or structures with 45° rotation.
Example:
Simulation 2 µm AZ1518
100 µm proximity gap
7 µm lines and spaces (horizontal periodic)
Mask Pattern HR-A-IFP Quadrupole-0°-IFP
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 10/14
Description:
Quadrupole-45°-IFP
Recommended gap range: Recommended application:
50 µm - 100 µm Squared structures and corners
Remark:
The Quadrupole - IFP is designed for structures with a quadratic shape or in a quadratic
arrangement. Depending on the gap and on the specific structures it can work for
orthogonal structures parallel to the mask grid or structures with 45° rotation.
Example:
Simulation 2 µm AZ1518
30 µm proximity gap
4,5 µm Squares (2D-periodic)
Mask Pattern HR-A-IFP Quadrupole-45°-IFP
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 11/14
Description:
Small Ring – IFP
Recommanded gap range: Recommended application:
50 µm - 150 µm Rotation-symmetric structures
Remark:
The ring formed IFPs are designed to reduce diffraction effects and they can work best
amongst others for rotation symmetric structures for bigger gaps.
Example:
Simulation 2 µm AZ1518
100 µm proximity gap
8 µm Squares (2D-periodic)
Mask HR-A-IFP Small Ring IFP
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 12/14
Description:
Big Ring – IFP
Recommended gap range: Recommended application:
20 µm - 50 µm Rotation-symmetric structures
Remark:
The ring formed IFPs are designed to reduce diffraction effects and they can work best
amongst others for rotation symmetric structures. The bigger ring formed IFP mostly works
better for smaller proximity gaps.
Example:
Simulation 2 µm AZ1518
30 µm proximity gap
3 µm Squares (horizontal periodic)
Mask Pattern HR-A-IFP Big Ring - IFP
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
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Current IFP-Sets (after July 2013)
IFP
Design Description MJB4
MA6
MA150
MA56
MA8Gen3 MA200
MA200Co MA300
D – IFP -- 100004089 -- -- --
HR – A - IFP 100005921 100004090 100006249 100018761 100018761
LGO - IFP 100005922 100004092 100006251 100018762 --
Big Circle - IFP 100006454 100004094 100006572 100006793 100006793
SMO IFP-Guide;130711uvo.Doc Uwe Vogler
20.08.2013 14/14
IFP-Sets (before July 2013)
IFP
Design Description MJB4
MA6
MA150
MA56
MA8Gen3 MA200
MA200Co MA300
D – IFP 100006456 100004089 100006557 100006794 100006794
HR – A - IFP 100005921 100004090 100006249 100018761 100018761
LGO - IFP 100005922 100004092 100006251 100018762 tbd
Medium Circle - IFP 100006453 100004093 100006558 100006792 100006792
Big Circle - IFP 100006454 100004094 100006572 100006793 100006793
Quadrupole – IFP 100006458 100004095 100006571 100006795 100006795
Quadrupole-45°-IFP 100006459 100004096 100006570 100006796 100006796
Small Ring – IFP 100006461 100004097 100006464 100006797 100006797
Big Ring – IFP 100006463 100004098 100006549 100006798 100006798