Specific Process Knowledge/Lithography/nLOF: Difference between revisions

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AZ nLOF 2020 is a negative UV photoresist, suitable for loft-off processes.
'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php/Specific_Process_Knowledge/Lithography/nLOF click here]'''
 
[[Category: Lithography|Resist]]
[[Category: Resist|AZ nLOF 2020]]
 
__TOC__
 
==Resist description==
AZ nLOF 2020 is a negative UV photoresist, suitable for lift-off processes.
 
==Spin coating==
[[Image:nLOFspincurves.JPG|500x500px|thumb|Spin curves for AZ nLOF 2020 using a 30s spin-off, and a 60s@110°C softbake]]
 
'''Typical spin parameters:'''
*Spin off: 30-60 s
*Soft bake: 60 s @ 110°C
 
<br clear="all" />


==Post-exposure bake==
==Post-exposure bake==
'''Typical PEB parameters:'''
*PEB temperature: 110°C
*PEB time: 60 s
The recommended PEB for nLOF is 60 seconds at 110°C, regardless of resist film thickness.


The recommended PEB for nLOF is 60s at 110°C, regardless of resist film thickness.


While 1min@110°C is adequate for Si substrates, less thermally conductive substrates (glass, III-V materials, chips bonded to carrier), have shoved problems using the standard PEB. These problems were largely solved by increasing the PEB time to 2min. Tests (on Aligner: Maskless 02) have shown that the lithographic performance of nLOF on Si is improved by using 2min@110°C PEB (less stitching, less bias, more negative profile).
'''PEB baking time investigation:'''
While 60 s @ 110°C is adequate for Si substrates, less thermally conductive substrates (glass, III-V materials, chips bonded to carrier), have shown problems using the standard PEB recipe.<br>
These problems were largely solved by increasing the PEB time to 120 s. Tests (on Aligner: Maskless 02) have shown that the lithographic performance of nLOF on Si is improved when using 120 s @ 110°C PEB (less stitching, less bias, more negative profile). A small report on the tests can be found [[media:nLOF_PEBtime_2019.pdf|'''here''']].


==Development==
==Development==
'''Development speed:'''
*Puddle development in 2.38% TMAH (AZ 726 MIF): ~4 µm/min


A 2µm nLOF resist film is fully developed in 20-30s using TMAH (AZ 726). However, the development can be continued to 60s in order to get a nore negative resist profile (increase the under-cut).
A 2 µm nLOF resist film is fully developed in ~30 s in 2.38% TMAH (AZ 726 MIF). However, the development can be continued to 60 s in order to get a more negative resist profile (due to increased under-cut).

Latest revision as of 14:30, 5 April 2023

This section, including all images and pictures, is created by DTU Nanolab staff unless otherwise stated.

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Resist description

AZ nLOF 2020 is a negative UV photoresist, suitable for lift-off processes.

Spin coating

Spin curves for AZ nLOF 2020 using a 30s spin-off, and a 60s@110°C softbake

Typical spin parameters:

  • Spin off: 30-60 s
  • Soft bake: 60 s @ 110°C


Post-exposure bake

Typical PEB parameters:

  • PEB temperature: 110°C
  • PEB time: 60 s


The recommended PEB for nLOF is 60 seconds at 110°C, regardless of resist film thickness.


PEB baking time investigation: While 60 s @ 110°C is adequate for Si substrates, less thermally conductive substrates (glass, III-V materials, chips bonded to carrier), have shown problems using the standard PEB recipe.
These problems were largely solved by increasing the PEB time to 120 s. Tests (on Aligner: Maskless 02) have shown that the lithographic performance of nLOF on Si is improved when using 120 s @ 110°C PEB (less stitching, less bias, more negative profile). A small report on the tests can be found here.

Development

Development speed:

  • Puddle development in 2.38% TMAH (AZ 726 MIF): ~4 µm/min


A 2 µm nLOF resist film is fully developed in ~30 s in 2.38% TMAH (AZ 726 MIF). However, the development can be continued to 60 s in order to get a more negative resist profile (due to increased under-cut).