Specific Process Knowledge/Etch/ICP Metal Etcher/Chromium/End point: Difference between revisions
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Made by Berit bghe @ DTU Nanolab | Made by Berit bghe @ DTU Nanolab | ||
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I was looking at trenches with sizes ranging from 200 nm to 2 µm in width. The masking materials was negative DUV resist: NUV 2300-0.5 of approximately 500 nm. The process flow can be seen here: [[:File:Process_flow_for_test_wafers xx.pdf]] | I was looking at trenches with sizes ranging from 200 nm to 2 µm in width. The masking materials was negative DUV resist: NUV 2300-0.5 of approximately 500 nm. The process flow can be seen here: [[:File:Process_flow_for_test_wafers xx.pdf]] | ||
== | ==Etch close to optimal== | ||
The etch rate is faster near the edge. Therefor the trenches are in general wider at the edges. Here all structures has been etched down to the SiO2 layer and the dimensions are close to being unaffected, especially in the middel. The sidewalls are close to 90 degrees; Sometimes a little positive and sometimes a little negative. | The etch rate is faster near the edge. Therefor the trenches are in general wider at the edges. Here all structures has been etched down to the SiO2 layer and the dimensions are close to being unaffected, especially in the middel. The sidewalls are close to 90 degrees; Sometimes a little positive and sometimes a little negative. To improve more the etch rate should be more uniform over the wafer and the Cr should be with small grain sizes. I stopped '''41 s after the end point curve 'SUM_C2' top point on the barc etch''' and '''170 s after the end point curve 'CR_Avg_5208' started to drop on the Cr etch'''. | ||
{| class="wikitable" | {| class="wikitable" | ||
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File:S047676midt_cr_02.jpg | File:S047676midt_cr_02.jpg | ||
File:S047676midt_cr_04.jpg | File:S047676midt_cr_04.jpg | ||
</gallery> | </gallery> | ||
| | | | ||
<gallery caption="S047676 X min, Feb-2025, wafer edge, 100 nm Cr mask, with 500 nm resist" widths="600px" heights="550px" perrow="1"> | <gallery caption="S047676 X min, Feb-2025, wafer edge, 100 nm Cr mask, with 500 nm resist" widths="600px" heights="550px" perrow="1"> | ||
File:S047676edge_cr_01.jpg | File:S047676edge_cr_01.jpg | ||
File:S047676edge_cr_04.jpg | File:S047676edge_cr_04.jpg | ||
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File:S047676edge_cr_11.jpg | File:S047676edge_cr_11.jpg | ||
File:S047676edge_cr_12.jpg | File:S047676edge_cr_12.jpg | ||
File:Emptyimage.jpg | |||
</gallery> | </gallery> | ||
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=== End point signal=== | === End point signal=== | ||
====Barc etch==== | ====Barc etch==== | ||
The End point signal shows a | The End point signal shows a top point after 5.5 s and I stopped the etch after 46.4 s giving ''' 41 s after the top point'''. | ||
<gallery caption="S047676 47s barc etch, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist" widths="600px" heights="550px" perrow="2"> | <gallery caption="S047676 47s barc etch, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist" widths="600px" heights="550px" perrow="2"> | ||
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==Etched too long== | ==Etched too long== | ||
The etch rate is faster near the edge. Therefor the trenches are in general wider at the edges. Here all structures has been etched down to the SiO2 layer but the dimensions | The etch rate is faster near the edge. Therefor the trenches are in general wider at the edges. Here all structures has been etched down to the SiO2 layer but the dimensions are affected, especially at the edge the trenches have become wider. The sidewalls are close to 90 degrees; Sometimes a little positive and sometimes a little negative. The improve more the etch time should be decreased. | ||
{| class="wikitable" | {| class="wikitable" | ||
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File:S047670edge_cr_04.jpg | File:S047670edge_cr_04.jpg | ||
File:S047670edge_cr_06.jpg | File:S047670edge_cr_06.jpg | ||
File:Emptyimage.jpg | |||
File:S047670edge_cr_08.jpg | File:S047670edge_cr_08.jpg | ||
File:S047670edge_cr_09.jpg | File:S047670edge_cr_09.jpg | ||
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|} | |} | ||
=== End point signal=== | |||
====Barc etch==== | |||
The End point signal shows a top point after 5.0 s and I stopped the etch after 60 s. | |||
<gallery caption="S047670 60s barc etch, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist" widths="600px" heights="550px" perrow="2"> | |||
File:20250213_02_endpoint.jpg | |||
File:20250213_02_toppoint.jpg | |||
</gallery> | |||
====Cr etch==== | |||
The End point signal shows a drop after 264 s and I stopped the etch after 7:45 min | |||
<gallery caption="S047670 7:45 min Cr etch, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist" widths="600px" heights="550px" perrow="2"> | |||
File:20250213_04_droppoint.jpg | |||
File:20250213_04_endpoint.jpg | |||
</gallery> | |||
==Etched too short== | ==Etched too short== | ||
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|} | |} | ||
=== End point signal=== | |||
====Barc etch==== | |||
The End point signal shows a top point after 6.5 s and I stopped the etch after 30 s. Too short | |||
<gallery caption="S047671 30s barc etch, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist" widths="600px" heights="550px" perrow="2"> | |||
File:20250213_06_endpoint.jpg | |||
File:20250213_06_toppoint.jpg | |||
</gallery> | |||
====Cr etch==== | |||
The End point signal shows a drop after 295 s and I stopped the etch after 7:00 min. Too short | |||
<gallery caption="S047671 7:00 min Cr etch, Feb-2025, wafer center, 100 nm Cr mask, with 500 nm resist" widths="600px" heights="550px" perrow="2"> | |||
File:20250213_08_droppoint.jpg | |||
File:20250213_08_endpoint.jpg | |||
</gallery> | |||