Specific Process Knowledge/Etch/Etching of Silicon Oxide/SiO2 etch using ASE/tests CHF3+H2

Tests performed with UV resist:

The tests were performed on a 100mm wafer patterned on MLA3, with 2.2um AZ5214E resist.

Recipe	Recipe parameters	Duration (min)	Date	SEM picture	Redeposition - top view	Profile angles	Etch rate in SiO2	Etch rate in resist (AZ5214E inverse)	Selectivity (SiO2:resist)
CHF3_t1	CHF3= 22.5 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C	12:00	04/09/2023				69.7 nm/min +/- 10.5%	57.3 nm/min +/- 12.9%	1.22
CHF3_t2	CHF3= 22.5 sccm Coil= 150W Platen= 25W Press= 2.5mTorr Temp= 20°C	25:00	04/09/2023				26.7 nm/min +/- 11.9%	24.2 nm/min +/- 21.1%	1.1
CHF3 t2	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 150W Platen= 25W Press= 2.5mTorr Temp= 20°C	10:00	22/09/2023				9,7 nm/min +/- 34.4%	1,8 nm/min +/- 46.5%	5.4
CHF3_t1	CHF3= 22.5 sccm H2= 10 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C	10:00	12/09/2023				59,6 nm/min +/- 12.9%	47,5 nm/min +/- 21.5%	1.25
CHF3_t1	CHF3= 22.5 sccm O2= 10 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C	10:00	11/09/2023				60,6 nm/min +/- 10.1%	130,8 nm/min +/- 8.8%	0.46
CHF3 t1	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C	10:00	20/09/2023				47,3 nm/min +/- 12%	26,4 nm/min +/- 17,4%	1.8
CHF3 t1	CHF3= 22.5 sccm H2= 35 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C	10:00	22/09/2023				36,5 nm/min +/- 10.6%	17,5 nm/min +/- 13.9%	2.09
CHF3 t1	CHF3= 35 sccm H2= 35 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C	10:00	22/09/2023				42 nm/min +/- 15.4%	23,8 nm/min +/- 22.2%	1.76
CHF3 t1	CHF3= 22.5 sccm CF4= 22.5 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C	10:00	22/09/2023				75,8 nm/min +/- 13.1%	74,9 nm/min +/- 10.8%	1.01
CHF3 t1	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 15W Press= 25mTorr Temp= 20°C	10:00	22/09/2023				-	-	no etch done, polymer deposited
CHF3 t1	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 0°C	10:00	22/09/2023				48 nm/min +/- 11.2%	23,3 nm/min +/- 13.7%	2.06

Tests performed with DUV resist:

The resist used was a negative DUV resist (UVN) with 915nm + 88nm BARC layer.

Recipe	Recipe parameters	Duration (min)	Date	SEM picture	Etch rate in SiO2	Etch rate in resist (UVN)	Selectivity (SiO2:resist)
CHF3_t1	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 30W Press= 2.5mTorr Temp= 20°C	10:00	13/11/23		47	24.6	1.9
CHF3_t1	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 45W Press= 2.5mTorr Temp= 20°C	10:00	13/11/23		59	30	1.9
CHF3_t1	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 45W Press= 2.5mTorr Temp= 0°C	10:00	07/12/23		96	56	1.7
CHF3_t2	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 150W Platen= 25W Press= 2.5mTorr Temp= 20°C	10:00	23/10/23		27	12,5	2.1
CHF3_t2	CHF3= 22.5 sccm H2= 22.5 sccm Coil= 150W Platen= 25W Press= 2.5mTorr Temp= 20°C	20:00	23/10/23		8.15	7.5	1.1

2SiO2 test - 5 jan 2024

Tested on chips (2*2cm). The following results were processed on chips bonded to a 100mm wafer. They were patterned with 915 UVN resist (DUV negative) and 65nm of BARC. The SiO2 layer was 2um (deposited on the C1 furnace).

Recipe	Time (min)	Date	SEM picture	Etch rate SiN (nm/min)	Etch rate resist (nm/min)	Selectivity (SiN:resist)
CHF3_t1 CHF3= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 30W Press= 2.5mTorr Temp= 20°C	10:00	25/01 -2024		250nm- 61,99 500nm- 68,12 1000nm- 74,7 2000nm- 76,55	250nm- 61,31 500nm- 49,85 1000nm- 46,83 2000nm- 47,3	250nm- 1,01 500nm- 1,37 1000nm- 1,6 2000nm- 1,62
CHF3_t1 CHF3= 22.5 sccm H2= 22.5 sccm Coil= 150W Platen= 45W Press= 2.5mTorr Temp= 20°C	10:00	25/01 -2024		250nm- 90,74 500nm- 84,63 1000nm- 89,33 2000nm- 94,34	250nm- 81,1 500nm- 53,77 1000nm- 52,23 2000nm- 54,81	250nm- 1,12 500nm- 1,57 1000nm- 1,71 2000nm- 1,72
CHF3_t2 CF4= 22.5 sccm H2= 22.5 sccm Coil= 150W Platen= 45W Press= 2.5mTorr Temp= 20°C	15:00	25/01 -2024	*it's visible that redeposits, so the ER and selectivity may not be correct.	250nm- 9,18 500nm- 22,46 1000nm- 28,03 2000nm- 28,75	250nm- 11,09 500nm- 3,96 1000nm- 4,22 2000nm- 4,40	250nm- 0,83 500nm- 5,67 1000nm- 6,64 2000nm- 6,5

Etch test of Silicon Nitride

The nitride layer deposited was 560nm, on the PECVD4 (recipe: Standard HF SiN with wafer clean, for 1h). They were patterned with 750 DUV resist and 65nm of BARC (exposure:355 J/m2, focus:-3.1). The following results were processed on chips (2*2cm) bonded to a 100mm dummy wafer.

Recipe	Time (min)	Date	SEM picture	Redeposition - top view	Etch rate SiN (nm/min)	Etch rate resist (nm/min)	Selectivity (SiN:resist)
CHF3_t1 CHF3= 22.5 sccm H2= 22.5 sccm Coil= 800W Platen= 15W Press= 2.5mTorr Temp= 20°C	2:30	29/02 -2024			250nm- 155,08 500nm- 170,32 1000nm- 174,45 2000nm- 179,76	250nm- 65,52 500nm- 56,36 1000nm- 64,56 2000nm- 68,84	250nm- 2,37 500nm- 3,02 1000nm- 2,70 2000nm- 2,61
CHF3_t2 CHF3= 22.5 sccm H2= 22.5 sccm Coil= 150W Platen= 45W Press= 2.5mTorr Temp= 20°C	5:00	29/02 -2024			250nm- 28,12 500nm- 41,86 1000nm- 66 2000nm- 63,62	250nm- 23,26 500nm- 22,60 1000nm- 16,74 2000nm- 15,34	250nm- 1.21 500nm- 1.85 1000nm- 3.94 2000nm- 4.15
CF4lowCP CF4= 22.5 sccm H2= 22.5 sccm Coil= 150W Platen= 45W Press= 2.5mTorr Temp= 20°C	5:00	29/02 -2024			250nm- 76,50 500nm- 73,92 1000nm- 73,94 2000nm- 76,50	250nm- 44,98 500nm- 33,52 1000nm- 31,16 2000nm- 25,66	250nm- 1,70 500nm- 2,21 1000nm- 2,37 2000nm- 2,98