Specific Process Knowledge/Lithography/Descum

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Descum results

Plasma asher 1

Descum results plasma asher 1. September 2019

Descum of AZ5214E resist on 50mm silicon wafer. Wafer was placed horisontally in chamber on a 100 mm carier wafer.

Note: Plasma asher was cold before use

Settings Etched Thickness (nm) ashing time (min) Recipe O2 flow N2 flow Power 1 2 5 7 10 10 1 70 70 150 14,2 16,3 47,6 123,2 854,3 862,1 2 500 0 200 8,1 32,9 271,1 495,6 446,2

Conny Hjort & Jesper Hanberg September 2019

Different resist descum results plasma asher 1. August 2021

Descum of different resists, AZ5214E, AZ701 MiR and AZ2020 nLOF, on a single 100mm wafer was tested. Wafer was placed vertically in the middle of glass carrier. Recipe setting was the same as in previous test in September 2019: 70ml/min O2, 70 ml/min N2, power 150W, different ashing time 1, 2, 3, 5 and 7 min run. Plasma Asher was cold before use, we observed minor temperature rise during processing, but not more than 5 degrees. Starting chambers pressure was around 0, 5 mbar.

1,5 um AZ5214E resist

Ashing time (min) 1 2 3 5 7 Etched Thickness (nm) 6,28 102,99 76,92 N/A N/A

1,5 um AZ5214E resist placed horizontally in the carrier

Ashing time (min) 1 2 3 5 7 Etched Thickness (nm) 63,03 143,32 304,29 372,59 N/A

1,5 um AZ701MiR resist

Ashing time (min) 1 2 3 5 7 Etched Thickness (nm) 268,88 199,54 219,03 200,86 292,15

1,5 um AZ 2020nLOF resist

Ashing time (min) 1 2 3 5 7 Etched Thickness (nm) 1,68 76,51 169,72 481,96 272,59

Plasma asher 2

Descum results plasma asher 2 - recipe 1

Descum of AZ Mir 701 resist on 100mm silicon wafer. Five wafers were placed vertically in chamber.

Experiment parameters:

O2 flow N2 flow Power recipe 1 100 100 150 recipe 2 500 0 200

recipe 1

Ashing time (min) 1 2 3 4 6 7 8 9 10 12 14 15 20 Etched Thickness (nm) 8,7 5,1 12,5 6,2 31,8 86,0 25,7 46,8 38,3 49,7 59,4 140,1 360,7 Initial temperature (°C) 28 21 31 21 22 28 25 24 21 24 24 22 22

Descum results plasma asher 2 - recipe 2

recipe 2

Ashing time (min) 1 2 3 4 5 6 7 8 10 12 15 20 Etched Thickness (nm) 8,1 9,4 16,8 55,2 44,0 47,5 42,5 55,1 85,3 122,4 184,8 305,9 Initial temperature (°C) 22 21 21 22 22 22 21 21 20 21 21 22

We can observe linear dependance of etched material on time after etching 7 minutes and more (recipe 2).

Jitka Urbánková & Jesper Hanberg December 2019

Plasma asher 3

Plasma Asher 3 is specially used for control descum process after lithography. Please notice that you only can process one 4 inch wafer or one small sampel ad time. Machine is equipt with 2 gaslines: oxydgen and nitrogen, but all test run with oxydgen as recommended by Diener.

Ashing of AZ MiR701 resist

Descum results for different power settings

You can use different strategy planing your descum: you can change power settings or you can vary chamber pressure during descum.

Testing different power settings

recipe settings: Oxydgen: 5 sccm under process Pressure: 0,2mbar

Experiment parameters:

FW/REV C2/C1 Power recipe 1 50/0 52/31 50% recipe 2 100/0 53/31 100% recipe 3 20/0 51/34 20%

Ashing of AZ5214E resist