299 Analysis

For data: 299step.xlsx, 299.pxp

Summary of 2991. Nb (15nm)/Al2O3(15nm Pad;4-0nm wedge)/Co(30nm)

2. Try to etch Nb with CF4

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 Dielectric5. 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• Vacc=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 5/1/12Comparison of etched area and shoulder(ref)

• Vacc= 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 05/01/2012Wedge

• 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 ShoulderAlO Pad 0Å All 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 MeasurementWedge All 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