Specific Process Knowledge/Lithography/Descum

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Descum results

Plasma asher 1

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 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

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

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

Experiment parameters:

	FW/REV	C2/C1	Oxydgen	Pressure
recipe 1	100/0	53/31	17	0,4
recipe 2	100/0	37/39	45	0,8