Test Data of Etching SiO2 with CHF3/CF4-Fluorine ICP Etcher

Fluorine ICP: 3.8mT, 50/900W, CHF3/CF4=10/30sccm, time=90 sec
Date	Sample #	Etch Rate (nm/min)	Etch Selectivity (SiO2/PR)	Averaged Sidewalls Angle	Observations/Notes	SEM Images (45d, cross section)
11/18/22	ND_FL_111822	268	1.01			[30D][CS]
11/07/22	ND_FL_110722	264.7	0.96			[30D] [CS]
10/24/22	ND_FL_102422	266.7	1.22			[30D][CS]
10/14/22	ND_FL_101422	249	0.82		Image drifted very slightly in SEM. May account for low selectivity.	[30D] [CS]
10/3/22	ND_FL_100322	228	1.10		Low etch rate.	[30D] [CS]
9/12/22	ND_FL_091222	278	1.33		high selectivity, may be due to new Si wafer	[30D] [CS]
8/26/22	ND_FL_082622	288	0.97		Low selectivity/e. rate	[30D] [CS]
8/22/22	ND_FL_082222	252.7	0.93		Lower selectivity/e. rate	[40D] [CS]
8/19/22	ND_Fl_081922	260.7	0.99		Low selectivity/etch rate	[30D][CS]
Change in operator - SEMs below (by NP) are erroneously measured to the trench, instead of flat plane.
5/18/22	NP_SiO2_Fl_10	308.7	1.19		still lower etch rate	[1] [2]
5/10/22	NP_SiO2_Fl_09	307.3	1.15		*etch rate seems lower*	[1] [2]
4/26/22	NP_SiO2_Fl_08	344.7	1.4			[1] [2]
4/20/22	NP_SiO2_Fl_07	354.7	1.11			[1] [2]
4/14/22	NP_SiO2_Fl_06	352.7	1.11			[1] [2]
3/29/22	NP_SiO2_Fl_05	334.7	1.07			[1][2]
3/09/22	NP_SiO2_Fl_04	358.9	1.06			[1] [2]
3/02/22	NP_SiO2_Fl_03	347	1.05			[1] [2]
2/23/22	NP_SiO2_Fl_02	362.7	1.02			[1] [2]