Oxford ICP Etcher - Process Control Data

Process Control Data - InP Ridge Etch (Oxford ICP Etcher)

PECVD SiO2 hardmask, patterned on Stepper #2 (AutoStep 200) & Panasonic ICP #1

InP Ridge Etch: 60°C, 3mT, 800W/65W, Cl2=18, H2=15, CH4=10sccm, time=5min00sec (300sec) Sample Size: 2” unpatterned InP wafer “dummy” pieces, surrounding 1x1cm patterned sample, ~30-40% SiO2 masking (NingC's pattern). Silicon carrier, no adhesive. Seasoning: 10min “Std Clean - O2/SF6 Chamber Clean 20C (Edit Time)”, then load 2” “dummy” unpatterned InP wafer pieces on Si carrier (rough side up) and run 5min of “Std InP Ridge Etch - Cl2/CH4/H2 60C” Sample Prep: Prior to dry etching, the sample is submerged in NH4OH : DI =  1:10 (3mL:30mL) for 1 min, then DI rinsed and N2 dried.
Date	Sample#	Etch Rate (nm/min)	Etch Selectivity (InP/SiO2)	Comments	SEM Images
9/30/22	ND_60c_093022	310	13.3	High etch rate and selectivity	[30D] [CS]
9/2/22	ND_60c_090622	246	7.5	Very low etch rate and selectivity	[30D] [CS]
9/1/22	ND_60c_090122	268	9.4	Low Etch rate/selectivity, could be due to recent Cl2 clean	[45D] [CS]
8/1/22	ND_60c_080122	298	9.9		[CS] [45D]
7/1/22	ND_60c_070122	294	11.9	Did not dip in NH4OH	[45D] [CS]
5/19/22	DJ_60c_007	326	TBA	After chamber vented, cleaned (wet + dry). Forgot NH4OH wet-etch before dry etch. ER and profile look nominal.	[45°1],[45°2] [XS]
5/11/22	NP_60c_010	322	9.76		[45°] [XS]
5/4/22	NP_60c_009	318	10.5		[45°] [XS]
4/27/22	NP_60c_008	320	9.2	directly after chamber clean. Identical results to before chamber clean. Chamber appeared clean when opened.	[45°] [XS]
4/26/22	NP_60c_007	312	9.93	day before chamber clean	[45°] [XS]
4/19/22	NP_60c_006	330	9.53	Chamber opened and brown gunk observed in chamber right after the etch was done. Etch rate unaffected.	[45°] [XS]
4/13/22	NP_60c_005	320	11.51	New mask pattern with long lines to cleave through.	[45°] [XS]
				↑ Changed mask pattern going forward (~50% open area), apparent etch rate changes due to measuring different features.
3/30/22	NP_60c_004	427	11.17	*etched for 3min* ~30-40% SiO2 masking (NingC's pattern)	[45°] [XS]
1/26/22	NP_1_26_003	452	12.9	~30-40% SiO2 masking (NingC's pattern)	[45°] [XS]

Etch Rate Dependence on Sample Size (Oxford ICP Etcher)

We have found that the size of the InP piece loaded (no adhesive, onto Silicon carrier wafer) affects the etch rate, but does not affect the etch profile - ie. etches are still smooth and vertical, but rate varies with sample area.

InP Ridge Etch: 60°C, 3mT, 800W/65W, Cl2=18, H2=15, CH4=10sccm, time=5min05sec (305sec) Silicon carrier, no adhesive.
Date	Sample#	Sample Size (dimensions, mm)	Sample Size (area, mm2)	Etch Rate (nm/min)	Etch Selectivity (InP/SiO2)	Comments	SEM Images
1/11/22	DJ_InPRidge	4.5 x 2.5	11.25	602	64.6nm left	~50% SiO2 masking (GCA Calibration pattern)	[1]
1/12/22	DJ_InPRidge	4.5 x 3	13.5	563	76.4nm left	~50% SiO2 masking (GCA Calibration pattern)	[2]
1/12/22	DJ_InP#3	4.5 x 3	13.5	612	71nm left	~50% SiO2 masking (GCA Calibration pattern)	[3]
1/26/22	NP_?	10 x 10	100	400-450	~250nm left	~30-40% SiO2 masking (NingC's pattern)
1/26/22	NP_?	1/4 of 50mm wafer	490	378	276nm left	~30-40% SiO2 masking (NingC's pattern)	[1]