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Specific Process Knowledge/Etch/ICP Metal Etcher/Chromium/Cr etch data from AS

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Test data on Cr etch development by Anders Simonsen @nbi.ku

Final recipe/result for Cr etch and etching down in the nitride in the AOE

The SEM images where done some after the Cr etch and some after both the Cr etch and the silicon nitride etch in the AOE using the recipe "SiN_AS". The important thing was to see how well the Cr works for masking the nitride given vertical and smooth sidewalls in the nitride. This was done on 30-50 nm thin Cr layers.

Recipe Pressure [mTorr] Coil power [W] Platen power [W] Total Flow Cl2+O2 [sccm] O2% Temp Time [s] CSAR etch rate [nm/min] CSAR rate w bond Etch rate [nm/min] Selectivity coil load coil tune plat load plat tune Comment
test13/laqs 10 300 15 30 23.33 20 28 100.71 42.86 0.43 This recipe was chosen over no. 12 because it did not need a large over etch of the Cr (no foot).


  • After Cr etch 75s with recipe 13 and nitride etch in the AOE 20s
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  • After Cr etch 75s with recipe 13 and nitride etch in the AOE 40s
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  • After Cr etch 85s with recipe 13 and nitride etch in the AOE 20s
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  • After Cr etch 90s with recipe 13 and nitride etch in the AOE 20s
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DOE experiments and results made on pattern free samples and samples patterned with UV lithography (SEM images)

Name Pressure [mTorr] Coil power [W] Platen power [W] Total Flow (Cl2+O2) [sccm] O2 % Selectivity Etch-rate [nm/min] Side-angle Corner Resist-damage Etch time [s] Etch depth [nm] Angle1 Radius1 Angle2
t5 5 300 25 40 25 0.21 49.03 25.5 319.5 1 175 57 28 331 23
t7 15 300 15 40 15 0.61 52.15 12 154.5 1 130 87 14 159 10
t8 5 500 15 40 25 0.4 49.50 39.5 228.5 1 120 101 42 169 37
t4 15 500 25 40 15 0.39 70.80 19.5 201 1 100 82 21 158 18
t2 5 300 25 80 15 0.21 40.54 40.5 262.5 3 185 75 42 274 39
t10 15 300 15 80 25 0.68 58.00 11.5 87 2 120 84 14 70 9
t6 5 500 15 80 15 0.43 49.24 29.5 300 5 145 81 29 362 30
t9 15 500 25 80 25 0.41 80.67 18.5 134.5 2 90 79 20 155 17
t1 10 400 20 60 20 0.35 63.13 17.5 288 2 115 79 20 292 15
t1R 10 400 20 60 20 0.4 57.14 20 186 2 105 100 24 232 16

Sem images of the DOE


Tests made after DOE with e-beam patterned samples

Recipe Pressure [mTorr] Coil power [W] Platen power [W] Total Flow Cl2+O2 [sccm] O2% Temp Time [s] CSAR etch rate [nm/min] CSAR rate w bond Etch rate [nm/min] Selectivity coil load coil tune plat load plat tune Comment
test11 15 300 15 40 25.00 20 23 80.87 73 52.17 0.65
test12 20 300 15 30 23.33 20 21 65.71 56 57.14 0.87 There seems to been a foot on the Cr after the Cr etch, therefor it was repeated for 2 min Cr etch to remove the foot
test13/laqs 10 300 15 30 23.33 20 28 100.71 42.86 0.43 This recipe was chosen over no. 12 because it did not need a large over etch of the Cr (no foot).
test14 10 300 15 40 25.00 20 30 88.00 40.00 0.45
nano (some other users recipe found on the ICP) 5 500 15 60 0.17 10 33 99.00 36.36 0.37 41 52 31 50 With strike pressure
langman 10 500 25 40 0.20 8 21 168.39 57.14 0.34 42 52 35 53 With strike pressure

SEM images of the tests after the DOE

These SEM images where done after both the Cr etch and the silicon nitride etch in the ICP metal using the recipe "Slow etch with carrier". The important thing was to see how well the Cr work for masking the nitride given vertical and smooth sidewalls.


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