Metallization of Polymers - American Chemical Society

Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 24, 2018 | https://pubs.acs.org Publication Date: November 9, 1990 | doi: 10.1021/bk-1990-0440.ch014

Chapter 14

Sensitivity of Plasma Fluorinated Polyimide and Poly(tetrafluoroethylene) to High-Energy Ion Beams During Rutherford Backscattering Spectroscopy F. Emmi, L. J. Matienzo, D. C. VanHart, and J. J. Kaufman Systems Technology Division, IBM Corporation, Endicott, NY 13760 Rutherford Backscattering Spectroscopy (RBS) is an established technique for analysis of inorganic materials. Recently, several applications of RBS on polymer films have been reported; however, the effect of ion beams on these surfaces has not been well documented. RBS has been used to determine fluorine distribution in polymers. Since ion beam irradiation of polymers can induce chemical changes, instrumental parameters need to be optimized to minimize damage. In this paper, plasma fluorinated PMDA-ODA films and PTFE were studied to understand beam interactions with the polymers as a function of irradiation time. X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM) and RBS were used to determine changes induced in the polymers by irradiation. For PTFE, irradiation produced films which were brittle and blistered; in contrast, the fluorinated PMDA-ODA films only darkened and had no blisters. Decomposition of these films resulted in defluorination and formation of C=CF bonds. The damage to PTFE extends to a depth approximately equal to the stopping power of the ions in the polymer. Polymer films are known to undergo changes under various types of irradiation by either crosslinking or degradation reactions (1). Studies have been performed which demonstrate how polymers are affected by ions (2-6), electrons (7,8), x-rays (8,9), and UV light irradiation (10-11). These interactions may produce changes in optical (12), electrical (13), or chemical (12-14) properties of the material. Polyimide films are extensively used in the microelectronic industry as insulators for multilevel interconnect systems because of their excellent thermal and electrical properties. In some cases, 0097-6156/90/044O-Ol%$06.00/0 © 1990 American Chemical Society Sacher et al.; Metallization of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

14. EMMI ET A L

197

High-Energy Ion Beams

t h e s e f i l m s can be e t c h e d , o r m o d i f i e d by 0 -CF^ plasmas t o change t h e i r p r o p e r t i e s . The i n t e r a c t i o n o f t h e plasma w i t h p o l y i m i d e s r e s u l t s i n d i f f e r e n t l e v e l s o f f l u o r i n a t i o n t h a t depend upon t h e gas composition. I n plasmas w i t h h i g h c o n c e n t r a t i o n s o f CF^, t h e p o l y i m i d e s u r f a c e becomes h i g h l y f l u o r i n a t e d , w i t h F/C r a t i o s a p p r o a c h i n g 2, s i m i l a r t o t h a t f o r p o l y t e t r a f l u o r o e t h y l e n e (PTFE) (15). An u n d e r s t a n d i n g o f plasma e t c h i n g mechanisms o f p o l y i m i d e i n Oj-CF^ m i x t u r e s r e q u i r e s measurements o f f l u o r i n e p e n e t r a t i o n . T r a d i t i o n a l a n a l y t i c a l t e c h n i q u e s , such as Ar+ i o n e t c h i n g performed d u r i n g SIMS o r XPS a n a l y s e s , can i n t r o d u c e erroneous r e s u l t s . As an a l t e r n a t i v e , t h e u s e o f R u t h e r f o r d B a c k s c a t t e r i n g S p e c t r o s c o p y (RBS) has been r e c e n t l y r e p o r t e d t o be a v i a b l e t e c h n i q u e t o study f l u o r i n e d i s t r i b u t i o n i n p o l y i m i d e f i l m s (16). A l t h o u g h RBS i s nond e s t r u c t i v e f o r most i n o r g a n i c m a t e r i a l s , beam i n t e r a c t i o n s w i t h o r g a n i c f i l m s o c c u r d u r i n g a n a l y s i s (3,17,18). I n o r d e r t o study metal d i f f u s i o n i n t o a fluoropolymer, o r a surface-modified l a y e r , changes i n t r o d u c e d by t h e a n a l y t i c a l t e c h n i q u e must be u n d e r s t o o d . P o l y i m i d e (PMDA-ODA) exposed t o i o n beams i n t h e energy r e g i o n between 1.9 and 3.6 MeV degrades by l o s s o f c a r b o n y l groups and t h e f o r m a t i o n o f a c a r b o n - r i c h s u r f a c e (3). T h i s d e g r a d a t i o n sequence has a l s o been o b s e r v e d f o r i r r a d i a t i o n w i t h Ar+ i o n s i n t h e keV energy range (6,19). I n t h i s s t u d y , plasma f l u o r i n a t e d p o l y i m i d e f i l m s o f v a r i o u s t h i c k n e s s e s were exposed t o a 2 MeV He + i o n beam a t d i f f e r e n t doses t o determine beam e f f e c t s . A t h i c k PTFE f i l m , i r r a d i a t e d under s i m i l a r c o n d i t i o n s , was a l s o examined; s u r f a c e changes and f l u o r i n e l o s s d u r i n g RBS a n a l y s i s were compared.


2

2

Experimental Sample P r e p a r a t i o n . PMDA-ODA p o l y i m i d e f i l m s were p r e p a r e d by s p i n c o a t i n g p o l y a m i c a c i d o n t o s i l i c o n w a f e r s and c u r i n g t o 360°C f o r 1 hour. The c u r e d f i l m t h i c k n e s s was a p p r o x i m a t e l y 10 urn. These samples were t r e a t e d downstream o f an 85% CF^-15% 0 microwave plasma f o r 30 minutes t o produce a f l u o r i n a t e d l a y e r , a p p r o x i m a t e l y 600Â t h i c k (16). F l u o r i n a t e d l a y e r s l e s s t h a n 600Â t h i c k were o b t a i n e d by a d d i t i o n a l t r e a t m e n t downstream from an 0 r i c h (85%) microwave plasma f o r v a r i o u s t i m e s . PTFE f i l m s (25 urn t h i c k ) were used as r e c e i v e d from Ε. I . duPont de Nemours I n c . 2

2

I n s t r u m e n t a l Techniques. I o n beam i r r a d i a t i o n o f samples was p e r f o r m e d by f o c u s i n g 2.1 MeV He + i o n s , u s i n g an Ionex Tandetron a c c e l e r a t o r , t o a spot s i z e o f a p p r o x i m a t e l y 4 mm . I o n beam c u r r e n t s were h e l d c o n s t a n t a t 10 nA. R a d i a t i o n e f f e c t s were d e t e r m i n e d by v a r y i n g t h e t o t a l charge on t h e sample between 0 and 20 μΟ. RBS s p e c t r a were c o l l e c t e d w i t h t h e samples a t an a n g l e o f 45° w i t h r e s p e c t t o t h e i n c i d e n t beam; a d d i t i o n a l i n s t r u m e n t a l d e t a i l s can be found elsewhere (20). S p e c t r a l s i m u l a t i o n s were performed u s i n g t h e RUMP method d e s i g n e d by D o o l i t t l e (21). X-ray p h o t o e l e c t r o n s p e c t r o s c o p y (XPS) was used t o a n a l y z e polymer s u r f a c e s b e f o r e and a f t e r i o n beam i r r a d i a t i o n . Data were c o l l e c t e d w i t h a S u r f a c e S c i e n c e SSX-100 s p e c t r o m e t e r u s i n g A l Κα x - r a y s i n t h e h i g h r e s o l u t i o n mode w i t h x - r a y s f o c u s e d t o a spot s i z e 2

2

Sacher et al.; Metallization of Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

198

METALLIZATION OF POLYMERS

o f 600 urn on the sample. B i n d i n g e n e r g i e s were r e f e r e n c e d t o t h e a d v e n t i t i o u s C I s l i n e a t 284.6 eV. SEM m i c r o g r a p h s were o b t a i n e d w i t h a Cambridge I n s t r u m e n t s S t e r e o s c a n 250 Mark I I e l e c t r o n m i c r o s c o p e a f t e r t h e sample had been c o a t e d w i t h a 200Â l a y e r o f P t . F o u r i e r t r a n s f o r m i n f r a - r e d (FTIR) s p e c t r a were c o l l e c t e d i n t h e t r a n s m i s s i o n mode u s i n g an IBM I n s t r u m e n t s IR-44 s p e c t r o m e t e r w i t h a s p e c t r a l r e s o l u t i o n o f 4 cm- . U s i n g a B r u k e r m i c r o s c o p e a t t a c h e d t o the s p e c t r o m e t e r , a r e a s between 10 ρ t o 80 ρ i n d i a m e t e r were analyzed. 1


R e s u l t s and D i s c u s s i o n The use o f h e l i u m i o n beams f o r c o n v e n t i o n a l RBS a n a l y s i s a l l o w s t h e d e t e c t i o n o f elements w i t h atomic numbers g r e a t e r t h a n two; w i t h computer s i m u l a t i o n , atomic r a t i o s and d i s t r i b u t i o n depths c a n be c a l c u l a t e d . F i g u r e 1 shows RBS s p e c t r a f o r an u n t r e a t e d PTFE f i l m and a PMDA-ODA f i l m a f t e r treatment i n a CF^ r i c h microwave plasma. I n the s p e c t r a , i n d i v i d u a l d a t a p o i n t s a r e r e p r e s e n t e d by open c i r c l e s and the c o m p u t e r - s i m u l a t e d s p e c t r a a r e shown as s o l i d l i n e s . For PTFE, o n l y c a r b o n and f l u o r i n e a r e o b s e r v e d ; f o r t h e p l a s m a - t r e a t e d p o l y i m i d e f i l m , c a r b o n , oxygen, n i t r o g e n and f l u o r i n e are found. F o r a g i v e n s e t o f e x p e r i m e n t a l p a r a m e t e r s , t h e c o n c e n t r a t i o n and depth o f an element i n a sample d e t e r m i n e t h e s p e c t r a l shape. F o r PTFE, f l u o r i n e i s homogeneously d i s t r i b u t e d t h r o u g h o u t the f i l m which r e s u l t s i n a s t e p - l i k e s i g n a l . I f the f l u o r i n a t e d l a y e r i s t h i n , t h e f l u o r i n e s i g n a l appears as a peak, as shown i n F i g u r e l b . PMDA-ODA f i l m s , f l u o r i n a t e d f o r 30 m i n u t e s , were exposed downstream o f an 0 r i c h microwave plasma f o r v a r i o u s times t o reduce the t o t a l amount o f f l u o r i n e . F i g u r e 2 compares t h e f l u o r i n e s i g n a l i n t e n s i t i e s (10 μΟ t o t a l charge) c o l l e c t e d a f t e r 0, 25, and 50 minutes o f t r e a t m e n t . U s i n g RBS, t h e i n i t i a l f l u o r i n e t h i c k n e s s was e s t i m a t e d t o be 600Â, w i t h a d i s t r i b u t i o n p r o f i l e r e p r e s e n t a t i v e o f a d i f f u s i o n - c o n t r o l l e d p r o c e s s (16). A f t e r treatments, the f l u o r i n e s i g n a l i n t e n s i t y d e c r e a s e s t o v a l u e s below the r e s o l u t i o n o f t h e i n s t r u m e n t , t h u s n o t a l l o w i n g f o r a c c u r a t e d i s t r i b u t i o n measurements. These f i l m s were used t o study changes induced by v a r i o u s i r r a d i a t i o n times. F l u o r i n e l o s s e s o c c u r r i n g d u r i n g a n a l y s i s , as a f u n c t i o n o f c o l l e c t e d c h a r g e , were m o n i t o r e d by i n t e g r a t i n g f l u o r i n e counts between c h a n n e l numbers 180 and 210. F i g u r e 3 d i s p l a y s t h e i n t e g r a t e d f l u o r i n e counts p e r 2.5 μΟ i n t e r v a l s f o r PTFE and t h e f l u o r i n a t e d p o l y i m i d e f i l m s . F o r each sample, t h e f l u o r i n e counts were the h i g h e s t i n i t i a l l y , b u t they d e c r e a s e d w i t h i r r a d i a t i o n t i m e , a p p r o a c h i n g a c o n s t a n t v a l u e . The b e h a v i o r o f t h e f l u o r i n a t e d p o l y i m i d e f i l m s and PTFE were s i m i l a r . F o l l o w i n g i o n i r r a d i a t i o n , the s u r f a c e s were s t u d i e d u s i n g XPS. A n a l y s e s were p e r f o r m e d on and o f f i r r a d i a t e d a r e a s ; d a t a were c o l l e c t e d u s i n g a spot s i z e w h i c h was c o n t a i n e d w i t h i n the i r r a d i a t e d a r e a . F i g u r e s 4a and 4b show the C I s and F I s r e g i o n s , r e s p e c t i v e l y , f o r a p o l y i m i d e f i l m t r e a t e d i n a CF^ r i c h plasma f o r 30 m i n u t e s . The C I s spectrum f o r the n o n - i r r a d i a t e d f i l m shows an envelope c o n t a i n i n g s i g n i f i c a n t c o n t r i b u t i o n s from CF bonds i n agreement w i t h p r e v i o u s l y r e p o r t e d d a t a (15). A f t e r i r r a d i a t i o n , a decrease i n t h e 2


EMMI ET AL.

199


Energy (MeV) 0.4

0.6

0.8

1.0

1

1

1


ι

100

150

]Λ_ r-

200

Channel Energy (MeV) 0.5 ι

0.6

0.7

0.8

0.9

1.0

1.1

1

1

1

1

1

I

b

100

120

140

160

Channel

180

200

220

F i g u r e 1. RBS S p e c t r a o f : (a) PTFE F i l m , and (b) PMDA-ODA f i l m exposed 30 minutes t o 85% CF^/15% 0 Plasma. S o l i d l i n e s represent the simulated spectra. 2


200


Energy (MeV) 0.85

0.90


ι

175

0.95

1

180

1.00

1

185

190

Channel

1.05

1

1

195

200

205

Figure 2. RBS signal intensity representative of f l u o r i n e d i s t r i b u t i o n , as a function of time i n 0 r i c h plasma. 2

Figure 3. RBS f l u o r i n e intensity per 2.5 μΟ i n t e r v a l as a function of t o t a l charge f o r PTFE and fluorinated PMDA-ODA films. Given times represent exposure of films to an 0 r i c h plasma. 2


EMMI ET AL.

201



2000

'300

'700

295 290 285 Binding Energy (eV)

695

F i g u r e 4. (a) XPS C I s b e f o r e ( s o l i d l i n e ) and (b) XPS F I s b e f o r e ( s o l i d l i n e ) and

690 685 680 Binding Energy (eV)

280

675

spectra f o r plasma-fluorinated polyimide a f t e r (dashed l i n e ) He + i r r a d i a t i o n . spectra f o r plasma-fluorinated polyimide a f t e r (dashed l i n e ) He + i r r a d i a t i o n . 2

2


202


CF peak i n t e n s i t y i s o b s e r v e d , w i t h a c o r r e s p o n d i n g i n c r e a s e f o r carbon m o e i t i e s a t lower b i n d i n g e n e r g i e s . A d e c r e a s e o f i n t e n s i t y was a l s o o b s e r v e d i n the F I s spectrum f o l l o w i n g i r r a d i a t i o n (see F i g u r e 4b). The o t h e r plasma t r e a t e d samples behaved i n s i m i l a r manner. XPS r e s u l t s (C I s and F I s ) o b t a i n e d f o r PTFE a r e shown i n F i g u r e s 5a and 5b on and o f f the i r r a d i a t e d a r e a s . From the C I s r e g i o n , the i n t e n s i t y o f the CF peak was s i g n i f i c a n t l y reduced upon i r r a d i a t i o n and, s i m i l a r t o the p l a s m a - t r e a t e d p o l y i m i d e f i l m s , an i n c r e a s e was o b s e r v e d f o r carbon s i g n a l s a t lower b i n d i n g e n e r g i e s . F l u o r i n e l o s s was a l s o d e t e c t e d i n t h e F I s spectrum, but the f l u o r i n e s i g n a l f o l l o w i n g i r r a d i a t i o n was found t o have a lower b i n d i n g energy, p o s s i b l y due t o a change i n the c r o s s l i n k i n g d e n s i t y , as i n the case o f PVDF ( 2 2 ) . The l o s s o f s u r f a c e f l u o r i n e due t o i o n i r r a d i a t i o n , as d e t e r m i n e d u s i n g XPS, i s shown i n T a b l e I ; the amount o f f l u o r i n e d e t e c t e d f o l l o w i n g i r r a d i a t i o n was s i m i l a r f o r a l l f i l m s . A d d i t i o n a l work was performed on PTFE t o g a i n f u r t h e r u n d e r s t a n d i n g o f beam i n t e r a c t i o n s w i t h the polymer.


2

Table I .

Atomic C o n c e n t r a t i o n o f F from

Sample 0 25 50

min

1

Before RBS

After RBS 2

50

16

min

1

45

17

min

1

44

18

65

15

PTFE 1

XPS

t i m e i n 0 - r i c h plasma 1 0 μC t o t a l charge 2

2

F i g u r e 6 shows atomic c o n c e n t r a t i o n s measured by XPS, on PTFE s u r f a c e s as a f u n c t i o n o f t o t a l charge d u r i n g RBS a n a l y s i s . W i t h exposure t i m e , t h e l e v e l o f f l u o r i n e d e t e c t e d d e c r e a s e s from 65% t o a p p r o x i m a t e l y 9%. Accompanying t h i s l o s s o f f l u o r i n e t h e r e i s an i n c r e a s e i n c a r b o n l e v e l s . Oxygen i s d e t e c t e d i n a l l o f the i r r a d i a t e d samples because o f s u r f a c e r e a c t i v i t y t o a i r d u r i n g t r a n s f e r from the RBS chamber t o the XPS i n s t r u m e n t . The amount o f oxygen i n c r e a s e s w i t h i o n beam e x p o s u r e , p o s s i b l y due t o a h i g h e r d e n s i t y of r e a c t i v e surface s i t e s . E x p e r i m e n t s t o c h a r a c t e r i z e the p h y s i c a l changes on i r r a d i a t e d a r e a s were p e r f o r m e d f o r plasma f l u o r i n a t e d p o l y i m i d e and f o r PTFE samples; o p t i c a l photographs of the damaged a r e a s a r e shown i n F i g u r e 7. PTFE f i l m s d e v e l o p b l i s t e r s d u r i n g He + i o n exposure, w h i l e the f l u o r i n a t e d p o l y i m i d e samples o n l y darken. The apparent d a r k e n i n g seen i n the PTFE photograph r e s u l t s from l i g h t s c a t t e r i n g by t h e b l i s t e r s u r f a c e s . More d e t a i l e d i n f o r m a t i o n on s u r f a c e morphology was o b t a i n e d u s i n g s c a n n i n g e l e c t r o n m i c r o s c o p y (SEM). 2


14. EMMI ET A L

203



1500

Binding Energy (eV) 4

1.0x10

695 F i g u r e 5. (a) XPS and a f t e r (dashed (b) XPS and a f t e r (dashed

690 685 680 Binding Energy (eV) C Is line) F Is line)

s p e c t r a f o r PTFE f i l m b e f o r e He + i r r a d i a t i o n . s p e c t r a f o r PTFE f i l m b e f o r e He + i r r a d i a t i o n .

675 (solid line)

2

(solid line)

2



204 METALLIZATION OF POLYMERS


205



14. EMMIETAL

2

Figure 7. Optical photographs of He + i r r a d i a t e d areas on plasma-fluorinated polyimide and PTFE films.


206


F i g u r e 8 shows SEM images o f PTFE f o l l o w i n g i o n beam exposure. At lower m a g n i f i c a t i o n (see F i g u r e 8 a ) , the appearance o f the damaged a r e a resembles t h a t o f a b r i t t l e f i l m . The h i g h e r m a g n i f i c a t i o n photograph (see F i g u r e 8b) shows a r e a s which had b l i s t e r e d and c r a c k e d ; c r a c k i n g may have o c c u r r e d d u r i n g sample t r a n s f e r . From SEM m i c r o g r a p h s , the t h i c k n e s s o f the b l i s t e r w a l l i s 6-7 um. C a l c u l a t i o n s , p e r f o r m e d t o e s t i m a t e t h e depth o f p e n e t r a t i o n o f a 2.1 MeV He + i o n beam a t 45°, i n t o PTFE, y i e l d e d a s t o p p i n g power o f 6 um. The method used t o determine the s t o p p i n g power o f the polymer i s d e s c r i b e d e l s e w h e r e ( 2 3 ) . The c a l c u l a t e d s t o p p i n g power and t h e measured depth o f damage a r e a p p r o x i m a t e l y the same. The b l i s t e r s r e s u l t from the e v o l u t i o n o f v o l a t i l e p r o d u c t s d u r i n g i r r a d i a t i o n . V o l a t i l e p r o d u c t s , d u r i n g exposure t o x - r a y o r i o n beams, have been d e t e c t e d by mass s p e c t r o m e t r y (9,24). FTIR s p e c t r a were o b t a i n e d from f o u r a r e a s o f an i r r a d i a t e d sample, as i n d i c a t e d i n F i g u r e 9. Peaks were o n l y o b s e r v e d i n the r e g i o n between 2000 and 800 cm- . S p e c t r a 1 through 4 were c o l l e c t e d as f o l l o w s : (1) o u t s i d e the i r r a d i a t e d a r e a , (2) t h r o u g h an i n t a c t b l i s t e r , (3) o n l y t h r o u g h the bottom o f the f i l m a f t e r the t o p p o r t i o n o f the b l i s t e r had been removed, and (4) t h r o u g h the top p o r t i o n o f the b l i s t e r o n l y . The c h a r a c t e r i s t i c spectrum o f a t h i c k PTFE f i l m ( r e g i o n 1) shows an i n t e n s e s i g n a l a s s i g n e d t o C F s t r e t c h i n g v i b r a t i o n s c a . , 1200 cm- . Changes o b s e r v e d i n an i r r a d i a t e d a r e a ( r e g i o n 2) i n c l u d e b r o a d e n i n g o f the C F s t r e t c h i n g f r e q u e n c y r e g i o n and the appearance o f a band a t a p p r o x i m a t e l y 1720 cm- . T h i s spectrum i s a summation o f b o t h the a l t e r e d r e g i o n and the b u l k PTFE. The changes o b s e r v e d i n spectrum 2 are p r i m a r i l y from c o n t r i b u t i o n s o f the a l t e r e d l a y e r ( r e g i o n 4 ) . The e x t e n t o f damage appears t o be c o n f i n e d w i t h i n t h e s t o p p i n g power o f the h e l i u m i o n s . I n f o r m a t i o n on the c h e m i c a l changes, r e s u l t i n g from i o n beam i r r a d i a t i o n , can be i d e n t i f i e d from spectrum 4. The b r o a d s i g n a l a t about 1720 cmi s a t t r i b u t e d t o C=0 and t o C=CF type bonds ( 2 5 ) . C=0 bonds l i k e l y d e v e l o p by r e a c t i o n o f t h e exposed s u r f a c e t o a i r d u r i n g sample t r a n s f e r from the i r r a d i a t i o n chamber; C=CF bonds develop during i r r a d i a t i o n . In a d d i t i o n , the CF v i b r a t i o n a t around 1200 cmbroadens towards lower wavenumbers, i n d i c a t i v e o f d e f l u o r i n a t i o n (26).


2

1

2

1

2

1

1

2

1

Conclusions Ion i r r a d i a t i o n o f PTFE and p l a s m a - f l u o r i n a t e d PMDA-ODA has been performed under t y p i c a l c o n d i t i o n s o f RBS a n a l y s i s . Loss o f f l u o r i n e i s o b s e r v e d on a l l f i l m s , e s p e c i a l l y a t t h e s t a r t o f i r r a d i a t i o n . D e c o m p o s i t i o n i s i n t r o d u c e d by the beam i n t e r a c t i o n w i t h the polymer; d e f l u o r i n a t i o n and f o r m a t i o n o f c a r b o n - c a r b o n double bonds a r e d e t e c t e d by XPS and FTIR. For PTFE, i r r a d i a t i o n produced f i l m s which were b r i t t l e and b l i s t e r e d . The c a l c u l a t e d s t o p p i n g power f o r He + i o n s and the e x p e r i m e n t a l l y measured depth o f damage a r e a p p r o x i m a t e l y the same. 2


EMMIETAL


207


14.

F i g u r e 8.

2

SEM m i c r o g r a p h s o f PTFE exposed t o He + i o n s .



208 METALLIZATION OF POLYMERS


14.

EMMIETAL


209

Literature Cited 1. 2. 3. 4.


5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

17. 18. 19.

20. 21. 22.

23. 24. 25. 26.

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RECEIVED May 16,

1990


Metallization of Polymers - American Chemical Society

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