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

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

Descum results for different power settings

Recipe settings: Kept oxygen and pressure settings constant at Oxydgen: 5 sccm under process; Pressure: 0,2mbar and vary power.

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%

Testing different pressure settings

Recipe settings: Kept power setting constant at Power: 100% and vary oxydgen flow during process.

Descum results for different pressure settings

Experiment parameters:

FW/REV C2/C1 Oxydgen Pressure recipe 1 100/0 53/31 5 0,2 recipe 2 100/0 37/38 45 0,8

Ashing of AZ5214E resist