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

002 - 725 to 0ev.1

Name

O 1s

Mg 2s

C 1s

F 1s

Pos .

531.0840

88.0840

285.6840

687.2840

FWHM

3.7781

2.9644

2.9239

2.8085

Area

113606.737

16075.373

17800.950

26550.296

At%

42.18

32.40

18.83

6.59

O 1s

Mg 2s

C 1s

F 1s

O KL L O 1s O 2s O 2p

O 2p3/ 2

O 2p1/ 2

Mg 2s

Mg KLL

Mg 2p3/2

Mg 2p

Mg 2p1/2 Mg 3s

C KLL C 1s

C 2p3/2

C 2p1/2

C 2p

F 1s F KL L

F 2s

F 2p1/2

F 2p3/2

F 2p

x 103

5

10

15

20

25

30

35

40

45

CP

S

700 600 500 400 300 200 100 0Bi ndi ng E nergy (eV)

002 - 725 to 0ev.1

Name

O 1s

Mg 2s

C 1s

F 1s

Pos .

532.6430

87.4430

285.2430

686.4430

FWHM

4.1286

3.0567

2.5848

2.5083

Area

113358.917

12847.838

19581.165

3493.100

At%

46.99

28.91

23.13

0.97

O 1s

Mg 2s

C 1s

F 1s

O KL L O 1s O 2s O 2p

O 2p3/ 2

O 2p1/ 2

Mg 2s

Mg KLL

Mg 2p3/2

Mg 2p

Mg 2p1/2 Mg 3s

C KLL C 1s

C 2p3/2

C 2p1/2

C 2p

F 1s F KL L

F 2s

F 2p1/2

F 2p3/2

F 2p

x 103

10

15

20

25

30

35

40

45

CP

S

700 600 500 400 300 200 100 0Bi ndi ng E nergy (eV)

MgO - Initial MgO – After 13 hrs electron exposure

F O C Mg

Double C peaks Double Peak is nowDifficult to resolve

F O CF O MgCF O

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

002 - 725 to 0ev.1

Name

O 1s

Mg 2s

C 1s

F 1s

Pos .

531.7730

88.7730

286.1730

688.1730

FWHM

3.6540

3.2402

2.9594

2.8683

Area

112782.340

16875.670

10412.380

22832.338

At%

45.23

36.74

11 .90

6.13

O 1s

Mg 2s

C 1s

F 1s

O KL L O 1s O 2s O 2p

O 2p3/ 2

O 2p1/ 2

Mg 2s

Mg KLL

Mg 2p3/2

Mg 2p

Mg 2p1/2 Mg 3s

C KLL C 1s

C 2p3/2

C 2p1/2

C 2p

F 1s F KL L

F 2s

F 2p1/2

F 2p3/2

F 2p

x 103

10

15

20

25

30

35

40

45

CP

S

700 600 500 400 300 200 100 0Bi ndi ng E nergy (eV)

MgCF O 002 - 725 to 0ev.1

Name

O 1s

Mg 2s

C 1s

F 1s

Pos .

531.6460

88.4460

286.2460

687.8460

FWHM

3.3626

2.6712

2.8959

2.8412

Area

137060.132

18319.946

4132.501

20595.681

At%

52.30

37.95

4.49

5.26

O 1s

Mg 2s

C 1s

F 1s

O KL L O 1s O 2s O 2p

O 2p3/ 2

O 2p1/ 2

Mg 2s

Mg KLL

Mg 2p3/2

Mg 2p

Mg 2p1/2 Mg 3s

C KLL C 1s

C 2p3/2

C 2p1/2

C 2p

F 1s F KL L

F 2s

F 2p1/2

F 2p3/2

F 2p

x 103

10

15

20

25

30

35

40

45

50

55

CP

S

700 600 500 400 300 200 100 0Bi ndi ng E nergy (eV)

10 seconds Ar+ sputtering 30 more seconds Ar+ sputtering

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

002 - 725 to 0ev.1

Name

O 1s

Mg 2s

C 1s

F 1s

Pos .

531.6460

88.4460

286.2460

687.8460

FWHM

3.3626

2.6712

2.8959

2.8412

Area

137060.132

18319.946

4132.501

20595.681

At%

52.30

37.95

4.49

5.26

O 1s

Mg 2s

C 1s

F 1s

O KL L O 1s O 2s O 2p

O 2p3/ 2

O 2p1/ 2

Mg 2s

Mg KLL

Mg 2p3/2

Mg 2p

Mg 2p1/2 Mg 3s

C KLL C 1s

C 2p3/2

C 2p1/2

C 2p

F 1s F KL L

F 2s

F 2p1/2

F 2p3/2

F 2p

x 103

10

15

20

25

30

35

40

45

50

55

CP

S

700 600 500 400 300 200 100 0Bi ndi ng E nergy (eV)

002 - 725 to 0ev.1

Name

O 1s

Mg 2s

C 1s

F 1s

Pos .

531.6670

88.6670

291.2670

687.4670

FWHM

3.8033

3.0062

3.5661

2.8868

Area

136981.559

18455.542

5057.131

41098.291

At%

49.08

35.90

5.16

9.85

O 1s

Mg 2s

C 1s

F 1s

O KL L O 1s O 2s O 2p

O 2p3/ 2

O 2p1/ 2

Mg 2s

Mg KLL

Mg 2p3/2

Mg 2p

Mg 2p1/2 Mg 3s

C KLL C 1s

C 2p3/2

C 2p1/2

C 2p

F 1s F KL L

F 2s

F 2p1/2

F 2p3/2

F 2p

x 103

5

10

15

20

25

30

35

40

45

50

CP

S

700 600 500 400 300 200 100 0Bi ndi ng E nergy (eV)

F O C MgF O CF O MgCF OAfter 40seconds total Ar+ sputtering After 18 more hours electron

exposure

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

0 200 400 600 800 10000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Seco

ndar

y E

lect

ron

Yie

ld (

per

prim

ary)

Primary Electron Energy (eV)

B C D E F G H I J K

0 200 400 600 800 10000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Seco

ndar

y E

lect

ron

Yie

ld (

per

prim

ary)

Primary Electron Energy (eV)

B C D E F G H I J K

0 200 400 600 800 10000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Seco

ndar

y E

lect

ron

Yie

ld (

per

prim

ary)

Primary Electron Energy (eV)

B C D E F G H I J K

0 200 400 600 800 10000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Seco

ndar

y E

lect

ron

Yie

ld (

per

prim

ary)

Primary Electron Energy (eV)

B C D E F G H I J K

1.) Initial 2.) 13hr Electron

3.) 40s Ar+ Sputter 4.) 18hr Electron

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

– 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

Mass Spec

Electron Gun

Heated Sample Holder

Main Chamber Attached Here

Mislocated in drawing, port is on right, not left, side

Transfer Arm Attached here

Turbopump attached here

EXISTING ITEMSREQ. MODIFICATIONSSCHEMATIC ERROR