1. Electron Exposure of MgO
Slade J. Jokela, I. Veryovkin, A. Zinovev

2. MgO – Sample QP118 MgO sample prepared by Qing Peng
6nm film of MgO on low resistivity Si
Sample had low secondary emission
Possibly due to long shelf time
Large amount of surface contamination

3. MgO After 600eV Electron Exposure
MgO - Initial
MgO – After 13 hrs electron exposure F F F F O O O O C C C Mg Mg
Double C peaks
Double Peak is now
Difficult to resolve

4. Comparison Before Electron Exposure (at. %)
After Electron Exposure (at. %) O
46.99
42.18 Mg
28.91
32.40 C
23.13
18.83 F
00.97
06.59

5. 5 keV Ar+ Sputtering 10 seconds Ar+ sputtering
30 more seconds Ar+ sputtering F O C Mg

6. Comparison 13hrs Electron Exposure (at%) 10s Ar+ Sputtering (at%)
30s more Ar+ Sputtering (at%) O
42.18
45.23
52.30 Mg
32.40
35.74
37.95 C
18.83
11.90
04.49 F
06.59
06.13
05.26

7. MgO After 600eV Electron Exposure
After 40seconds total Ar+ sputtering
After 18 more hours electron exposure F F F F O O O O C C C Mg Mg

8. Comparison After Ar+ Sputtering (at%)
After 18hrs More Electron Exposure (at. %) O
52.30
49.08 Mg
37.95
35.90 C
04.49
05.16 F
05.26
09.85

9. Further Ar+ Sputtering
120 seconds of Ar+ sputtering
Carbon peaks virtually eliminated
Fluorine peak reduced to 3 at.%
240 seconds of Ar+ sputtering
Fluorine peak reduced to 1.9 at.%
Si substrate becoming visible in XPS spectrum
360 seconds of Ar+ sputtering
Si is obviously showing through
Fluorine peak ‘increased’ to 2.3%
Such a small increase is difficult to confirm

10. Secondary Emission
Emission spectra were taken sequentially and are labeled from B to K (1 to 10 respectively)
Each spectrum is an average of 5 taken over 1.5 minutes (0.3 minutes for each)
Periodic ‘noise’ was later eliminated by delaying scans by a very short period so that the coupled signal did not reinforce itself in the average.

11. Secondary Emission 1.) Initial 2.) 13hr Electron 3.) 40s Ar+ Sputter

12. Summary of Data Analysis
This was an initial test on an old sample
Test should be repeated on a newer and on a thicker sample
I will look back at older samples to see if emission degradation has occurred
Secondary emission determination has changed since then, so it may not be possible to directly compare older spectra to newer spectra
Different electron energies should be studied

13. Mass Spectrometry Surface desorption Electron stimulated desorption
EXISTING ITEMS
REQ. MODIFICATIONS
SCHEMATIC ERROR
Surface desorption
Electron stimulated desorption
Temperature Prog. Desorp.
If we know what is being removed from the surface during these processes, we may be able to accelerate the scrubbing process
Electron Gun
Mass Spec
Main Chamber Attached Here
Transfer Arm Attached here
Heated Sample Holder
Mislocated in drawing, port is on right, not left, side
Turbopump attached here