Oxford Etcher - Sample Size Effect on Etch Rate

Sample Size Effect on Etch Rate (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 etch 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]