299 Analysis For data: 299step.xlsx, 299.pxp

Summary of Nb (15nm)/Al 2 O 3 (15nm Pad;4-0nm wedge)/Co(30nm) 2.Try to etch Nb with CF 4 3.Nb etch recipe: 100 W RIE, 130 mTorr, CF4 = 40 sccm, O2 = 4 sccm. 4.Visually there are 3 distinct regions of etching: Pad, Wedge, No Dielectric 5.In wedge region there seems to be residue. With EDX, there seems to be excess Oxygen, Si, and Cl peaks. 6.No apparent etching of Nb or Co in wedge region. 7.In addition to EDX, Optical (Zygo) and Physical (DekTek) Profilometry was used. 8.Zygo measurements give erroneous results in the wedge area. Measures too much etching (~500Å). The Dektek measures an added film thickness (residue) of that same amount (~500Å) in the wedge region. 9.In the other 2 regions, Metal and AlO pad, etching is less (50Å and 150Å respectively) with no residue. 10.Try to bake the residue off, but no effect. Could be due to higher pressure in the oven that nothing was observed.

4/29/12 EDX broad beam Broad region, scanned region is 10um x 10um V acc =10k with Mag = 10k x No difference in Co etching Seems to be a Cl peak in etched area Large O peak in Wedge No difference in Nb etching In AlO Pad, Al peak present

All Metal Area 5/1/12 Comparison of etched area and shoulder(ref) V acc = 10kV and 60k x zoom Measurement region 2um x 2um Better able to resolve just being on the shoulder and off the shoulder to compare No Difference in Co peak, but compared to the AlO region the peak counts are less. No detectable O in the etched area or shoulder No difference in Nb in shoulder or etched region Small Au signal from pad No Al or Si

EDX of etch 05/01/2012 Wedge No Difference in Co peaks No difference in Nb Nb same amount, but may etched but redeposited on surface. (? Nb, NbO, NbF) Extra Si peak In the etched region; Extra O Small Al peak in unetched region No Al in etched region AlO is completely etched, resolve O and Al disappearance. Old Data (wide range) and New (narrow range) all line up Al is a factor of 10 less in the shoulder than in the pad compared the etched region.

AlO Pad 5/1/12 No Difference in the Co peak No Nb difference, but Au peak dominates Nb signal Large Al signal in the shoulder region, less in etched region. Indicates AlO gets etched Oxygen signal is pronounced in shoulder No Si

Questions 1.What is the nature of the residue. Is it Nb, NbO or NbF? Answer using XPS.

299 Zygo With Zygo scans

Summary of Zygo Results Avg Ti/Au step: 800ű62Å Etch step:= Varies on location. All Metal it’s 150Å, Pad~50Å, Wedge~500Å In the wedge region the Zygo erroneously says the etch is very deep. Physical measurements indicate an extra residue on the surface. Some regions show no etching

“Sample 3” On Wedge Clear etch shoulder 890Å Shoulder

No/Small Etch Shoulder AlO Pad 0ÅAll Metal 100Å

Profilometer Data Using the Profilometer it’s seen that instead of etching ~500Å, there is actually a build up in the Wedge Region. EDX supports this interpretation Slight etching in the AlO pad (150Å) and All metal region(50Å) Tried to bake the containments off of the surface

Pre Bake Measurement WedgeAll Metal

Post Bake Wedge Measurement Attempt to get the residue off of the surface after the bake. Pumped oven to 100 Torr and reached a temp of 210°C No change to step height. It still seems that the residue is on the surface..

Excel Data

XPS Measurements by Carrie Donley

Wedge Region Recap: This is the area with contamination No Nb signature found!!?? – No Al signature found except on the plateau – No AlF, AlCl CoO present (O migration from Al2O3?) SiO also present F peak seen, probably CF4 Cl present in salt form. Few Peaks seen Nb2O5 seen on flat Signature of CoO present SiO present<25% than wedge A Fluorine salt All Metal Region Pad Region No Nb Few Signatures seen AlO present and the peak is higher than in Plateau