Test Data of etching SiO2 with CHF3/CF4-ICP1

ICP#1: 0.5Pa, 50/900W, CHF3/CF4=10/30 sccm, time=210 sec
Date	Sample#	Etch Rate (nm/min)	Etch Selectivity (SiO2/PR)	Averaged Sidewall Angle (o)	SEM Images
1/28/2019	I11901	110	1.35		[1]
5/29/2019	I11903	105	1.41		[2]
1/13/2020	I12001	78.0	1.06		[3]
1/13 rate is low by ~20%, so chamber was wet-cleaned on 1/21/2020. Data below for 1/23 shows rate returned to "normal".
1/23/2020	I12002	109	1.16		[4]
2/28/2020	I12003	119	1.17	56.6