Specific Process Knowledge/Etch/ICP Metal Etcher/silicon oxide

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It is possible to etch SiO2 in the ICP metal etcher but it is not designed for it and the results are not fantastic. It is a challenge to get a good selectivity to resist (typically in the range of 1:1 or worse) and it is probably not possible to get a profile angle of 90 degrees. More likely about 75-85 degrees.

Slow etch of SiO2 with resist as masking material - using a 6" carrier wafer with recess

This recipe can be used for slow etching of SiO2 with resist as masking material. Here are some test results presented.

Parameter	Resist mask
Coil Power [W]	200
Platen Power [W]	25
Platen temperature [oC]	0
CF4 flow [sccm]	20
H2 flow [sccm]	10
Pressure [mTorr]	3

Results	Test on wafer with 50% load (Travka 50), by BGHE @danchip	100% load on 100mm wafers with Barc and KRF (no mask)
Etch rate of thermal oxide	44.1 nm/min (50% etch load) (01-02-2014)
Selectivity to resist [:1]	~0.9 (SiO2:resist)	~1.25:1 (Barc:KRF)
Wafer uniformity (100mm)	±1.6% (01-02-2014)
Profile [o]	Take a look at the images but be aware that the resist profile was not good to begin with.
Wafer uniformity map (click on the image to view a larger image)	Contour plot of the etch rate over the wafer, 9 points measured
SEM profile images	Resist profile before etch Resist profiler after etch 01-02-2014. Resist profiler after etch 01-02-2014. No line width reduction observed.
Etch rate in barc		50 nm/min (2014-09-09)
Etch rate in KRF resist	40 nm/min (2014-09-09)