Specific Process Knowledge/Lithography/nLOF: Difference between revisions

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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: nLOF PEB time 2019.

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).

Solvent development

Cross-linking negative resists have the potential to be developed using organic solvents instead of the normally used alkaline aqueous solutions. A quick test of this was carried out by Thomas Anhøj @ DTU Nanolab, showing that nLOF 2020 could potentially be used for water-free lithography.

A small report on the test can be found here: nLOF solvent development 2024.

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-'''Feedback to this section''': '''[mailto:labadviser@danchip.dtu.dk?Subject=Feed%20back%20from%20page%20http://http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Lithography/nLOF click here]'''
+{{:Specific Process Knowledge/Lithography/authors_generic}}
+'''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]]
-[[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==
+'''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.
+===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).
-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 when using 2min@110°C PEB (less stitching, less bias, more negative profile). A small report on the tests can be seen [[media:nLOF_PEBtime_2019.pdf|here]].
+A small report on the tests can be found here: [[media:nLOF_PEBtime_2019.pdf|'''nLOF PEB time 2019''']].
 ==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).
+===Solvent development===
+Cross-linking negative resists have the potential to be developed using organic solvents instead of the normally used alkaline aqueous solutions. A quick test of this was carried out by Thomas Anhøj @ DTU Nanolab, showing that nLOF 2020 could potentially be used for water-free lithography.
-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 small report on the test can be found here: [[media:nLOF_solventdev_2024.pdf|'''nLOF solvent development 2024''']].