Chapter 4 Results and Discussion
4.1 XPS Analysis of Surface Chemical States of ODPA-BADB Polyimide
contained eight types of carbon atoms and two types of oxygen. C1s spectrum includes eight main components However, we limited fitting of C1s signal to three main carbon components, which can be broken in the plasma treatment process [67].
The binding energy of the main components fitting in C1s and O1s signal was listed in table 1. [68]
The binding energy was corrected by comparing real Au peak in experiment with ideal peak. The shift of bending energy was found 1.7 eV, this value was used to correct data in the fitting peak process. The binding energies and composition quantification of ODPA-BADB polyimide before and after oxygen plasma treatment was characterized from table 4.2 to table 4.9 correspond with XPS C1s and O1s spectra were illustrated in Figure 4.2 through Figure 4.9. The component ratios were determined from percent area of each component in the XPS spectra.
Table 4.2 showed the surface component ratio of untreated ODPA-BADB polyimide, it includes three components, namely C-C (284.8eV), C-O-C (285.8eV) and C=O (288.6 eV) due to the component ratios 83.58 %, 10.08 % and 6.34 %.
Table 4.3 listed the PI surface components after using oxygen plasma treatment at 50W RF power for 1 minute. The result showed the component ratio of C-C bonding
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decrease from 85.53% to 45.43%, the polar groups as C-O-C and C=O increased from 10.08% to 19.5% and 6.34 to 13.95 %. The new polar group C-OH occurred at a position peak 283.7 eV and increase from 0% to 21.12%. Table 4.4 and table 4.5 summarized the PI surface components modified by oxygen plasma treatment at 50W RF power and 100W RF power for 5 minutes. The components ratio were similar with the result in table 4.3. Therefore we can conclude the polar groups ratio increase after oxygen plasma treatment and independence with condition treatment.
The binding energy of O1s was fixed as 532 eV [69], the untreated PI surface components' ratio was listed in table 4.6 include two components C-O-C and C=O with the components ratio were 41.1% and 58.9%, respectably. After Oxygen plasma treated at 50W RF power for 1 minute, the component ratio of C-O-C and C=O decrease from 41.1% to 20.8% and 58.9 to 36.67%. The new component C-OH occurred and increased from 0% to 42.53 %. The surface chemical states of polyimide treated by oxygen plasma at 50W RF power and 100W RF power for 5 minutes was shown in table 4.8 and 4.9. The component's ratio similar and independent with power treatment and time treatment.
The C1s and O1s spectra and fitted peaks of PI film before and after treatment were shown in Figure 4.2 through Figure 4.9. New contribute correspond with C-OH
bonding was found as C9 in the carbon 1s spectra and O3 in oxygen 1s spectra showed.
The reason of formation new group will be discuss later.
1 1
Figure 4. 1. Binding states of the (a) carbon and (b) oxygen atoms in the repeating unit of ODPA-BADB polyimide
Table 4. 1. Main components and their binding energies fitting in C 1s and O 1s XPS signals of ODPA-BADB polyimide
Signal Component Binding energy
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Table 4. 2. Carbon 1s spectrum: binding energies and composition quantification of untreated ODPA-BADB polyimide film.
Component Peak BE (ev) Area %
C-C 284.8 12009.29 83.58
C-O-C 285.8 1448.87 10.08
C=O 288.6 910.98 6.34
Table 4. 3. Carbon 1s spectrum: binding energies and composition quantification of ODPA-BADB polyimide film modified by oxygen plasma at 50W RF Power, time treatment for 1min
Component Peak BE (ev) Area %
C-C 284.8 10473.74 45.43
C-O-C 285.8 4503.04 19.5
C=O 288.6 3216.95 13.95
C-OH 287.3 4861.73 21.12
Table 4. 4. Carbon 1s spectrum: binding energies and composition quantification of ODPA-BADB polyimide film modified by oxygen plasma at 50W RF Power, time treatment for 5 min
Component Peak BE (ev) Area %
C-C 284.8 11416.57 46.32
C-O-C 285.8 4467.45 18.13
C=O 288.6 3340.14 13.55
C-OH 287.3 5421.54 22
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Table 4. 5. Carbon 1s spectrum: binding energies and composition quantification of ODPA-BADB polyimide film modified by oxygen plasma at 100W RF Power, time treatment for 5min
292 290 288 286 284 282
C1s
Intensity
Binding energy (ev)
C-C C-O-C C=O
Figure 4. 2. The XPS C 1s spectra of untreated ODPA-BADB polyimide films
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292 290 288 286 284 282 280
Intensiy
Binding energy (eV)
C-C C-O-C C=O C-OH
C1s
Figure 4. 3. The XPS C 1s spectra of ODPA-BADB polyimide films oxygen
plasma treated at 50W RF Power, time treatment for 1min
292 290 288 286 284 282 280
C-C C-O-C C=O C-OH
In te ns ity
Binding energy (eV)
C1s
Figure 4. 4. The XPS C 1s spectra of ODPA-BADB polyimide films oxygen
plasma treated at 50W RF Power, time treatment for 5 mins
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292 290 288 286 284 282 280
Intensity
Binding energy (eV) C-C
C-O-C C=O C-OH
C1s
Figure 4. 5. The XPS C 1s spectra of ODPA-BADB polyimide films oxygen
plasma treated at 100W RF Power, time treatment for 5 mins
Table 4. 6. Oxygen 1s spectrum: binding energies and composition quantification of untreated ODPA-BADB polyimide film
Component Peak BE (eV) Area %
C-O-C 533.3 4013.76 41.1
C=O 532 5749.93 58.9
Table 4. 7. Oxygen 1s spectrum: binding energies and composition quantification of ODPA-BADB polyimide film modified by oxygen plasma at 50W RF Power, time treatment for 1min
Component Peak BE (eV) Area %
C-O-C 533.3 2894.21 20.8
C=O 532 5099.6 36.67
C-OH 532.5 5912.84 42.53
Table 4. 8. Carbon 1s spectrum: binding energies and composition quantification of ODPA-BADB polyimide film modified by oxygen plasma at 50W RF Power, time treatment for 5 mins
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Table 4. 9. Oxygen 1s spectrum: binding energies and composition quantification of ODPA-BADB polyimide film modified by oxygen plasma at 100W RF Power, time treatment for 5 mins
Component Peak BE (eV) Area %
537 536 535 534 533 532 531 530 529
C-O-C C=O
Intensity
Binding energy (eV)
O1s
Figure 4. 6. The XPS C 1s spectra of untreated ODPA-BADB polyimide films
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536 535 534 533 532 531 530
Intensity
Binding energy (ev) C-O-C
C=O C-OH
O1s
Figure 4. 7. The XPS O1s spectra of ODPA-BADB polyimide films oxygen
plasma treated at 50W RF Power, time treatment for 1min
536 534 532 530 528
C-O-C C=O C-OH
In te n s ity
Binding energy (ev)
O1s
Figure 4. 8. The XPS O1s spectra of ODPA-BADB polyimide films oxygen plasma treated at 50W RF Power, time treatment for 5mins
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536 534 532 530 528
Intensity
Binding energy (ev) C-O-C
C=O C-OH
O1s
Figure 4. 9. The XPS O1s spectra of ODPA-BADB polyimide films oxygen plasma treated at 100W RF Power, time treatment for 5mins
4.2 Surface Morphology and Roughness of PI by Using AFM
Figures 4.10 and 4.11 show the surface morphologies of ODPA-BADB polyimide as-prepared and after oxygen plasma treatment at 50 W and 100 W for 5 minutes. The root-mean-square (RMS) roughness of the PI increased with the increasing RF power. RMS roughness of PI was increased from 0.509 nm prior to plasma treatment to 2.993 nm using 50 W treatment, and 13.319 nm using 100 W treatment.
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(a)
(b)
(c)
Figure 4. 10. The AFM two-dimensional images of the PI surface: (a) as-prepared (untreated), (b) oxygen plasma treatment at 50 W for 5 mins, (c) oxygen plasma treatment at 100 W for 5 mins
(a) (b)
(c)
Figure 4. 11. The AFM three-dimensional images of the PI surface: (a) as-prepared (untreated), (b) oxygen plasma treatment at 50 W for 5 mins, (c) oxygen plasma treatment at 100 W for 5 mins
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