STUDY OF THE CHARACTERISTICS OF INORGANIC LAYERS OBTAINED BY PLASMA-CHEMICAL PRECIPITATION ON POLYMERS

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STUDY OF THE CHARACTERISTICS OF INORGANIC LAYERS OBTAINED BY PLASMA-CHEMICAL PRECIPITATION ON

POLYMERS

M. Tsapovetsky, M. Gougnyin, S. Aleksandrov, V. Chimpoake, R.

Nemchenok, G. Pascalov

To cite this version:

M. Tsapovetsky, M. Gougnyin, S. Aleksandrov, V. Chimpoake, R. Nemchenok, et al.. STUDY

OF THE CHARACTERISTICS OF INORGANIC LAYERS OBTAINED BY PLASMA-CHEMICAL

PRECIPITATION ON POLYMERS. Journal de Physique Colloques, 1990, 51 (C5), pp.C5-343-C5-

351. �10.1051/jphyscol:1990541�. �jpa-00230850�

STUDY OF THE CHARACTERISTICS OF INORGANIC LAYERS OBTAINED BY PLASMA-CHEMICAL PRECIPITATION ON POLYMERS

M.I. TSAPOVETSKY, M. Yu. GOUGNYIN, S.E. ALEKSANDROV, V.T. CHIMPOAKE, R.L. NEMCHENOK and G.Z. PASCALOV

Institut of Macro Molecular Compounds of the Academy of Sciences of the USSR, Leningrad 3, V.O., Bolshoy pr, 199004, U.S.S.R.

Rdsumd

-

Les methodes de l'XPS, l a s p e c t r o s c o p i e IR d e l a r Q f l e x i o n de s u r f a - c e e t l a s p e c t r o s c o p i e B l e c t r o n i q u e o n t Q t k u t i l i s Q e s pour l l B t u d e d e s cog- ches i n o r g a n i q u e s obtenues s u r l e polymQre pendant l a s y n t h Q s e plasmochimi- que. Les couches de SigN4, ALN, SiO ont e t e s y n t h Q t i s 6 e s 2 sur l a s u r f a c e des pol,$tnicYes p a r d e s mQthodes plasmochimiques d i v e r s e s . Les i n v e s t i g a t i o n s p a r l a mdthode XPS a n t ddmontrdes que l e s u b s t r a t polymdrique p a r t i c i p e a c t i v e - ment au processus de l a synthkse. L l Q t u d e p a r l a microscopie Q l e c t r o n i q u e d e s Q t a p e s i n i t i a l e s a d6montrQe que l a c r o i s s a n c e commence p a r l a f o r m a t i o n de noyaux ayant l e s t r u c t u r e de d e n d r i t e s t y p i q u e s p o u r l e s couches polymdri- ques deposQes. Les r Q s u l t a t s expdrimentaux permettent de t i r e r l a c o n c l u s i o n q u ' i l e s t p o s s i b l e d 9 0 b t e n i r l e s d i v e r s e s s t r u c t u r e s polymQre-inorganiques

& l l e x c e p t i o n entihrement de l l i n t e r f a c e .

A b s t r a c t

-

I n o r g a n i c f i l m s o b t a i n e d on t h e polymer support d u r i n g plasma- -chemical s y n t h e s i s have i n v e s t i g a t e d by XPS, I R - r e f l e c t a n c e s p e c t r o s c o p y and SEM. The l a y e r s of S i N ALN, SiO were o b t a i n e d of plasma c h i m i c a l p r e

3 4' 2

c i p i t a t i o n on t h e s u r f a c e of polyimide f i l m s . The r e s u l t s of XPS i n v e s t i g a - t i o n s showed t h a t t h e polymer s u p p o r t t a k e s a n a c t i v e p a r t i n t h e formation of t h e i n o r g a n i c f i l m . The d a t a of e l e c t r o n microscopy i n t h e i n i t i a l s t a g e s of f i l m growth i n d i c a t e t h a t i n t h e f i r s t s t a g e n u c l e i a r e formed. They a r e uniformly d i s t r i b u t e d on t h e s u r f a c e of t h e polymer support and e x h i b i t a pronounced d e n d r i t e s t r u c t u r e . The experimental r e s u l t s s u g g e s t t h a t under experimental c o n d i t i o n s m8,kea i t p o s s i b l e t o o b t a i n v a r i o u s polymer-inorga- n i c s t r u c t u r e devoid of t h e i n t e r f a c e .

INTRODUCTION

A t p r e s e n t t h e plasma-chemical t r e a t m e n t of v a r i o u s m a t e r i a l s i n c l u d i n g po- lymers i s one of t h e most r a p i d l y developing t r e n d s i n m a t e r i a l s c i e n c e . The plasma-chemical p r e c i p i t a t i o n of v a r i o u s i n o r g a n i c Layers ( S i N ALN, S i 0 2 ,

3 4'

e t c . ) on n e u t r a l s u p p o r t s (semiconductors and m e t a l s ) h a s l o n g ago become one of t h e most i m p o r t a n t t e c h n o l o g i c a l o p e r a t i o n s i n t h e micro e l e c t r o n i c p r o d u c t i o n /1,2/. The p r o p e r t i e s of t h e s e l a y e r s have been s t u d i e d by d i f f e - r e n t methods and t h e main e f f o r t s of t h e r e s e a r c h e r s i s d i r e c t e d t o t h e es- t a b l i s h m e n t of t h e c o r r e l a t i o n between t h e c o n d i t i o n s o f p r e c i p i t a t i o n and s y n t h e s i s and t h e c h a r a c t e r i s t i c s of t h e l a y e r s .

The t r e a t m e n t of t h e polymers i n plasma f o r i m p a r t i n g new p r o p e r t i e s t o t h e s u r f a c e by d e p o s i t i n g on i t quasi-polymer l a y e r s one a l s o known and w i - d e l y i n v e s t i g a t e d and used / 3 / . When t h e s y n t h e s i s of polymer l a y e r s i s c a r e r i e d out under t h e c o n d i t i o n s of non-equilibrium low-temperature plasma, a

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1990541

COLLOQUE DE PHYSIQUE

plasma-forming g a s , o r g a n i c monomers and fragments of macromolecules a r e used. A s a r e s u l t o f t h e s y n t h e s i s , a l a y e r i s formed t h e s t o i c h i o m e t r y o f which i s c l o s e t o t h a t of t h e polymer. I n s t r u c t u r e i t i s u s u a l l y a d e n s e l y cro,ss-linked system. These l a y e r s may be d e p o s i t e d on any o r g a n i c and i n o r - g a n i c s u b s t r a t e s .

I n o u r opinion, t h e plasma-chemical t r e a t m e n t of o r g a n i c and i n o r g a n i c ma- t e r i a l s h a s many s i m i l a r f e a t u r s : v i r t u a l l y t h e same t e c h n o l o g i c a l equipment and c e r t a i n s i m i l a r i t y between t h e chemical and p h y s i c a l p r o c e s s e s o f l a y e r formation. However, t h e r e a r e d i f f e r e n c e s between t h e plasma-chemical syn- t h e s i s o f quasi-polymer l a y e r s on t h e polymer s u r f a c e and t h e d e p o s i t i o n o f i n o r g a n i c l a y e r s on t h e s u r f a c e o f t h e semiconductor. This I s mainly due t o t h e r o l e played by t h e s u b s t r a t e . I n o r g a n i c s u b s t r a t e i s n e u t r a l component, whereas a polymer s u b s t r a t e c a n probably t a k e p a r t i n t h e process.

Hence, i t i s i n t e r e s t i n g t o o b t a i n a n i n o r g a n i c l a y e r on t h e polymer s u r - f a c e by plasma-chemical d e p o s i t i o n and t o i n v e s t i g a t e i t s c h a r a c t e r i s t i c s , This i s t h e purpose of t h e p r e s e n t paper.

EXPERIMENTAL METHODS

The Si02, S i N and A1N f i l m s were o b t a i n e d by t h e plasma-chemical growth 3 4

on a polymer. The p r o p e r t i e s of s i l i c o n n i t r i d e l a y e r s grown on polyimide were i n v e s t i g a t e d .

S i l i c o n n i t r i d e f i l m s d e p o s i t e d on polyimide i n a s p e c i a l l y c o n s t r u c t e d experimental i n s t a l l a t i o n e n s u r i n g t h e p o s s i b i l i t y of p l a c i n g i t o u t s i d e the i n i t i a t i o n r a n g e o f h i g h frequency d i s c h a r g e (Hg.1). SiH ₄

+

^{4% h? and N2}

( h i g h ~ u r i t y ) were used a s i n i t i a l substances. N2 was i n t r o d u c e d i n t o one of t h e r e a c t o r chambers i n which t h e low-temperature glow-discharge plasma w a s generated. The h i g h frequency d i s c h a r g e plasma wa$excited i n accordence w i t h t h e i n d u c t i v e scheme a t a frequency of 1.76 M& and a g e n e r a t o r power of 2 KW. The n i t r o g e n plasma was d i r e c t e d i n t o t h e second r e a c t o r chamber i n t o which an a r g o n - s i l a n e m i x t u r e was a l s o charged where t h e s u b s t r a t e w a s p l a c e d on a h e a t e r . The s i l i c o n n i t r i d e films were d e p o s i t e d on s u b s t r a t e h e a t e d t o 600 K a t t h e o v e r a l l p r e s s u r e of t h e r e a c t i o n m i x t u r e i n t h e r e a c - t o r 50-60 Pa. Polyimide of t h e f o l l o w i n g chemical formula was u s e d as t h e s u b s t r a t e :

(Kapt on-H)

t h e f i l m t h i c k n e s s was 4 0 ~ ~ . T h i s polymer was chosen because i t i s a high- -temperature d i e l e c t r i c s t a b l e t o i o n i z i n g r a d i a t i o n /4/. Polyimide w a s coa- t e d w i t h s i l i c o n n i t r i d e of d i f f e r e n t t h i c k n e s s e s (from 50 t o 1500

x),

^The

t h i c k n e s s was checked by simultaneous d e p o s i t i o n o f s i l i c o n n i t r i d e on a si- l i c o n s u b s t r a t e . The l a y e r s were i n v e s t i g a t e d by d i f f e r e n t methodes.

The XPS-spectra were t a k e n on a n Kratos XSAM-800 s p e c t r o m e t r a w i t h t h e e x c i t a t i o n by X-ray Mg-radiation w i t h a n energy of 1253.7 eV. Binding ener-

heater SinLI N,

Figure 1.. Schematic diagram of plasma-chemical i n s t a l l a t i o n

g i e s have been determined by u s i n g t h e C 1s peak (from i n s i t u c o n t a m i n a t i o n ) a t 285 eV. The survey s p e c t r a at a b i n d i n g energy of 0-1000 eV and s p e c t r a of s i n g l e - p h o t o e l e c t r o n l i n e s C I s , N Is, 0 Is and S i 2p were taken. The re- c o r d i n g of s p e c t r a and t h e mathematical p r o c e s s i n g were c a r r i e d o u t w i t h DS- -800 system. The p r e c i s i o n of t h e b i n d i n g energy d e t e r m i n a t i o n was 0.1 eV and t h a t of t h e q u a n t i t a t i v e a n a l y s i s was 70%. The I R - r e f l e c t i o n s p e c t r a we- r e recorded w i t h a P e r k i n Elmer 580 B spectrophotometer. The topology of t h e l a y e r s was a t u d i e d w i t h a Hitachi-750 scanning e l e c t r o n microscope.

P4

RESULTS

Survey s p e c t r a of t h e s i l i c o n n i t r i d e l a y e r s of d i f f e r e n t t h i c k n e s s e s on a Kapton-H polymer f i l m showed t h a t w i t h i n c r e a s i n g l a y e r t h i c k n e s s t h e i n - t e n s i t y of S i 2p and N Is peaks i n c r e a s e s and t h a t o f C Is peaks d e c r e a s e s . The a n a l y s i s of t h e f i n e s t r u c t u r e shows t h a t t h e peaks a r e s u p e r p o s i t i o n s of s e v e r a l peaks. This may be r e l a t e d t o t h e f a c t t h a t d i f f e r e n t t y p e s o f co- v a l e n t bonds a r e p r e s e n t i n t h e l a y e r s o b t a i n e d by t h i s method. Pig.2 and 3 show t h e f i n e s t r u c t u r e of t h e S i 2p peaks f o r l a y e r s o f d i f f e r e n t t h i c k n e s - s e s .

The mathematical p r o c e s s i n g of XPS h i g h - r e s o l u t i o n s p e c t r a made i t p o s s i - b l e t o determine t h e b i n d i n g energy and atomic c o n c e n t r a t i o n f o r each e l e - ment. These v a l u e s a r e g i v e n i n Table 1. The t a b l e shows t h a t when t h e l a y e r

t h i c k n e s s i n c r e a s e s , t h e atomic c o n c e n t r a t i o n of element changes and s h i f t s i n b i n d i n g energy appear. These s h i f t s a r e u s u a l l y caused by t h e excess nega- t i v e charge g e n e r a t e d by t h e surrounding s p h e r e c o n s i s t i n g o f t h e c h a r g e s of neighbouring i o n s l o c a t e d a t d i f f e r e n t d i s t a n c e s from t h e c e n t r a l i o n /5/.

I n o u r c a s e t h i s s h i f t i n d i c a t e s t h a t t h e number of i o n s i n t h e c o o r d i n a t i o n s p h e r e changes. The XPS s p e c t r a of a model compound, s i l i c o n o x y n i t r i d e (ICS, USSR), were a l s o analysed. The r e s u l t s a r e g i v e n i n Table 2.

The a n a l y s i s of r e f l e c t i o n s p e c t r a o b t a i n e d from t h e some s u r f a c e mode i t

COLLOQUE DE PHYSIQUE

b i n d i n g ehergy, eV

0

F i g u r e 2. S i 2p XPS s p e c t r a f o r a s i l i c o n n i t r i d e l a y e r 100 A t h i c k ; c u r v e r e s o l v e d t o show two peaks

solid lined sum

. of the t w o curve /

binding energy, eV

0

F i g u r e 3. S i 2p XPS s p e c t r a f o r a s i l i c o n n i t r i d e l a y e r 1000 A t h i c k ; c u r v e r e s o l v e d t o show two .peaks.

TABLE 1. Binding E n e r g i e s (BE) and Atomic C o n c e n t r a t i o n (AC) f o r S i , N, 0 and G on t h e s u r f a c e of polyimide f i l m s .

?hLc kness 2P N 1s 0 Is C 1s ^d

of deposi-

t i o n o l a y e r , BE,eV AC,% BE,eV AC,% BE,eV *C,% BE,eV *C,%-:

A

1. 100 102.3 14.26 398.2 11.5 532.5 19.76 285.0 14.-41

:

103.5 11-80 399.3 4.69 533.5 13.46 286.2 4.90

:

400.6 0.96 288.3 2.35 :

p o s s i b l e t o i d e n t i f y some c h a r a c t e r i s t i c bands. The p r e s e n c e of a n absorban-

range of 3600 om-l may be a s s i g n e d t o t h e s t r e t c h i n g v i b r a t i o n of t h e f r e e Si-OH group. The a n a l y s i s of t h e r e s u l t s of i n v e s t i g a t i o n of f i l m s u r f a c e s

0

w i t h l a y e r s l e s s t h a n 100 A i n t h i c k n e s s i s some what d i f f i c u l t becanse cha- r a c t e r i s t i c s polyimi.de bands a r e p r e s e n t i n t h e r a n g e s of 800-900 cm", 1920 om"', e t c . ~ d w e v e r , i t i s p o s s i b l e t o s i n g l e out t h e c h a r a c t e r i s t i c bands of t h e bondes formed a f t e r t r e a t m e n t , such as C=O s t r e t c h i n g v i b r a t i o n s of 1655 cm"' i n t h e NH-C=O. The 1620 om-I band i s a s s i g n e d t o bending v i b r a t i o n s of amide-11. T h i s i s i n good agreement w i t h t h e XPS d a t a and i n d i c a t e t h a t t h e polymer s u b s t r a t e i s d e s t r o y e d d u r i n g t h e s y n t h e s i s .

TABLE 11. Binding Energies f o r S i l i c o n O x y n i t r i d e

S i 2p N 1s 0 Is

BE, eV 102.3 398.2 533.0

104.0

The i n i t i a l s t a g e s of f i l m growth and t h e topology o f continuous l a y e r , i s n a t u r a l l y , of t h e g r a t e s t i n t e r e s t . Fig. 4 shows t h e m i c r o g r a f s of a s u r f a c e w i t h a growing i n o r g a n i o l a y e r . Fig.4a shows a h i g h c o n c e n t r a t i o n o f n u c l e i of d i f f e r e n t types. Pig.48and C show-the f i n e s t r u c t u r e of a t y p i c a l n u c l e i - es. The n u c l e i a r e u s u a l l y of t h e d e n d r i t e type. It i s noteworthy t h a t t h e number of n u c l e i i s h i g h and t h e i r s i z e s a r e cluite d i f f e r e n t . Pig.5 shows

0

t h e s u r f a c e of a s i l i c o n n i t r i d e l a y e r 1000 A-thick. It i s c l e a r t h a t a f t e r t h e n u c l e i c o a l e s c e , u s u a l r e g u l a r f i l m growth t a k e s p l a c e . Moreover, t h e co- mparison of Fig. 4c and 5 shows, t h a t t h e r e l i e f of t h i s l a y e r v e r t u a l l y do-

e s n o t d i f f e r from t h a t of t h e i n i t i a l polymer f i l m . Pores and o t h e r s i m i l a r d e f f e c t s were n o t d e t e c t e d .

DISCUSSION

The comparison of t h e r e s u l t s g i v e n i n Table 1 and shown i n e l e c t r o n mic- rographs o f t h e l a y e r s shows t h a t t h e s u r f a c e of sample 1 i s an i s l a n d s t r u c - t u r e o f t h e new phase on t h e s u r f a c e of t h e polyimide f i l m . The s u r f a c e o f sample 2 i s a c o n t i n u o u s l a y e r formed a s a r e s u l t of t h e plasma-chemical syn- t h e s i s . The d e p t h of t h e XPS a n a l y s i s i s 50-70 A, 0 hence, i n c a s e 1 b o t h t h e new phase and t h e s u r f a c e of t h e polyimide f i l m a f t e r t r e a t m e n t i n plasma we- r e analyeed. I n t h e second c a s e o n l y t h e new s y n t h e s i z e s l a y e r w a s analysed.

It can be seen from Table 1 t h a t t h e s u r f a c e of sample 1 i s a more complex s t r u c t u r e t h a n t h a t of sample 2.

Now t h e r e s u l t s of XPS of t h e s u r f a c e l a y e r o f sample 2 w i l l be conside- red. S i 2p

-

102.3 eV b i n d i n g energy can be a s s i g n e d t o t h e S-N chemical bo- nd whereas 103.3 eV can be a s s i g n e d t o t h e S-0 bond /6/. The p o s i t i o n of theN

C5-348 COLLOQUE DE PHYSIQUE

E g u r e 4. Scanning e l e c t r o n microscope p i c t u r e from a s u r f a c e covered with s i l i c o n n i t r i d e l a y e r . 100 X-thick. ( a ) Magnification x500.

(b) Magnification x2000.

Figure 4 ( c ) . Magnification X? 0000.

1s peak i s higher t h a n t h a t of t h e i n d i v i d u a l compound, 397.5 eV, which i s probably due t o t h e presence of a more e l e c t r o n a g o t i v e 0 atom i n t h e environ- ment. The 0 I s , 532.5 eV, l i n e , i n t u r n , a l s o i n d i c a t e s t h a t s i l i c o n oxide

(533.0 eV BE) can be formed. As a l r e a d y t h e s h i f t i n BE i s determined by t h e excess n e g a t i v e charges of t h e c o o r d i n a t i o n sphere. Hence, compounds of t h e following types: Si-I?-0, 0-Si-N, C-Si-0, etc., can e x i s t i n t h e i s l a n d s t r u c -

und a g r e e w i t h t h o s e o b t a i n e d f o r t h e s u r f a c e l a y e r s , and i t can be s t a t e d t h a t s i l i c o n oxynitri.de i s p r e s e n t i n a s u r f a c e l a y e r of samples. The presel?- c e of t h e 0 Is 532.4 eV and 533.1 eV BE i n d i c a t e s t h a t b o t h s i l i c o n o x y n i t r i - de and s i l i c o n oxide can be formed. The C Is 285.0 eV peak may be e i t h e r a s i g n a l of hydrocarbons l o c a t e d on t h e f i l m s u r f a c e t r a n s p o r t e d t h e r e from t h e vacuum system of t h e s p e c t r o m e t r a (sample 2 ) o r a s i g n a l t y p i c a l of t h e benzene r i n g (sample I ) . The 286.6 eV BE may be a s s i g n e d t o oxygen-contai- n i n g f u n c t i o n a l groups, such a s C-0, C-OOH and C-0-C=O /7/, whereas t h e 288.3 eV BE c a n be a s s i g n e d t o amide and imide groups. The p o s i t i o n of t h e N 1s 399.3 eV and 400.6 eV BE may be assigned t o n i t r o g e n - c o n t a i n i n g amide and W i d e groups / B / . It should be n o t e d t h a t t h e atomic c o n c e n t r a t i o n of eleme- n t s b e i n g t h e p r o d u c t s of polyimi.de d e g r a d a t i o n i s much lower t h a n t h a t of t h e p r o d u c t s of i n o r g a n i c s y n t h e s i s and e v i d e n t l y d e c r e a s e s w i t h t h e i n c r e a - s i n g t h i c k n e s s of t h e l a y e r a s shown by sample 2.

There i s a n i n t e r e s t i n g i n t h e t r e a t m e n t of t h e chemical s t r u c t u r e of ino- r g a n i c l a y e r s . T h i s f a c t i s probably due t o h i g h oxygen c o n c e n t r a t i o n i n t h e s u r f a c e l a y e r . T h i s h i g h c o n c e n t r a t i o n cannot be ensured by t h e p r o d u c t s of polymer d e g r a d a t i o n a l o n e t h e c o n d i t i o n of plasma-chemical s y n t h e s i s cannot be t h e r e a s o n f o r t h i s h i g h c o n c e n t r a t i o n e i t h e r . Most probably, this h i g h oxygen c o n c e n t r a t i o n on t h e s u r f a c e i s caused by t h e i n t e r a c t i o n between t h e s u r f a c e ( a c t i v a t e d a s a r e s u l t of t h e i n t e r a c t i o n w i t h t h e plasma) and t h e athrnosphere. Hence, t h e s u r f a c e becomes covered by ~ q u a s i s i l i c o n o x i d e ~ . The t o t a l s t o i c h i o m e t r i c composition of t h e s u r f a c e (assuming t h a t t h e 285.0 eV BE i n b o t h c a s e s r e t e r s t o hydrocarbons) i s S i , .OOO, .37N0.65C0,28 f o r f i l m 1

COLLOQUE DE PHYSIQUE

and Si,.0000~73N0.66 f o r f i l m 2.

I n t h i s work we d i d n o t i n t e n d t o a n a l y e e i n d e t a i l t h e mechanisms of ge- n e r a t i o n , growth and c o a l e s c e n c e of n u c l e i . However, t h e q u a n t i t y and t h e va- r i a t i o n s of t y p e s and s i z e s observed i n t h e photos (Fig.4 and 5 ) suggest t h a t t h e n u c l e i w i t h t h e c r i t i c a l r a d i u s can be v e r y s m a l l under t h e experimental c o n d i t i o n s ( a few atoms o r even s m a l l e r ) . T h i s f a o t , i n t u r n , shows t h a t che- m i c a l i n t e r a c t i o n s t a k e p l a c e between t h e plasma elements and t h e s u r f a c e ,

and t h e polymer p a r t i c i p a t e s v e r y a c t i v e l y i n t h e formation of t h e l a y e r . I n t h i s s i t u a t i o n t h e growth of t h e n u c l e i e s proceeds most probably a s a r e s u l t of t h e aZtachment of p a r t i c l e s from t h e g a s phase because t h e d i f f u s i o n o f t h e s e v e r y a c t i v e p a r t i c l e s by any c o n s i d e r a b l e d i s t a n c e a l o n g t h e s u r f a c e is improbable.

The d e n d r i t e s t r u c t u r e of t h e n u c l e i (Fig.4B) shows, i n o u r o p i n i o n , t h a t , a t l e a s t i n t h e i n i t i a l p e r i o d t h e fragments of t h e polymer molecules a c t i v e - l y p a r t i c i p a t e i n n u c l e a t i o n and t h e n u c l e i have a complex polymer-inorganic composition. This i s even more p r o b a b l e because t h e d e n d r i t e s t r u c t u r e i s u s u a l l y observed i n t h e d e p o s i t i o n of a t h e r m a l l y evaporated polymer on v a r i - ous s u b s t r a t e s /g/. There i s probably a c e r t a i n s i m i l a r i t y between t h e pro- c e s s of t h e thermal d e p o s i t i o n of t h e polymer on a s u b s t r a t e and t h e p r o c e s s d e s c r i b e d here. I n t h e l a t t e r c a s e t h e polymer s u b s t r a t e t a k e s t h e most a c t i - v e p a r t i n l a y e r formation.

The above d a t a make i t p o s s i b l e t o develop i n t h e most approximate form a model f o r formation of t h e i n o r g a n i c l a y e r on t h e polymer s u r f a c e . The poly- mer heated t o 1 573 K i s placed o u t s i d e t h e a c t i v e zone but i s n e v e r h t e l e s s

submitted t o a c o n t i n u o u s a c t i o n of t h e plasma components. A t h i g h temperatu- r e t h i s a c t i o n may l e a d t o c a t o s t r o p h i c changes i n t h e polymer s u r f a c e . The chemical bonds on t h e s u r f a c e break, and r a d i c a l a r e g e n e r a t e d at h i g h con- c e n t r a t i o n . A t t h i s c o n d i t i o n s t h e polymer s u r f a c e may be a wcontinuous f r e e r a d i c a l f 1 . I n . t h e r e g i o n n e a r t h e s u r f a c e , a c o n s i d e r a b l e c o n c e n t r a t i o n of gaseous d e g r a d a t i o n p r o d u c t s of t h e polymer ( t h e fragments of t h e main st- r u c t u r e ) i s observed. The plasma elements i n t h i s r e g i o n r e a c t w i t h degrada- t i o n p r o d u c t s and t h e n touching t h e s u r f a c e form c o v a l e n t bonds w i t h i t . Co- n s e q u e n t l y , t h e primary s t r u c t u r e of l a y e r s o b t a i n e d by plasma-chemical de- p o s i t i o n i s a complex polymer-inorganic composite c o n s i s t i n g of t h e elements of t h e a c t i v e g a s and t h e polymer d e g r a d a t i o n p r o d u c t s c o v a l e n t l y bonded t o each o t h e r and t o t h e polymer s u r f a c e .

Table 1 (sample 1 ) and E g . 4 p r o v i d e d i r e c t c o n f i r m a t i o n s of t h i s process.

A s t h e p r o c e s s c o n t i n u e s and t h e a r e a of t h e new phase i n c r e a s e s . A s a r e s u - l t , t h e c o n c e n t r a t i o n of d e g r a d a t i o n p r o d u c t s i n t h e l a y e r n e a r t h e s u r f a c e d e c r e a s e s . A s t h e d i s t a n c e between t h e f i l m s u r f a c e and t h e t e n t a t i v e boun- dary between t h e polymer and t h e i n o r g a n i c l a y e r i n c r e a s e s , t h e s t r u c t u r e of t h e l a y e r becomes determined t o t h e i n c r e a s i n g e x t e n t by t h e c o n d i t i o n s o f

makes i t p o s s i b l e t o o b t a i n v a r i o u s polymer-inorganic s t r u c t u r e devoid of t h e i n t e r f a c e .

Acknovledgment. We a r e g r a t e f u l t o V.A.Shukaxev, T.A.Antonova and Yu.M.Boy- archuk f o r c a r r y i n g a u t t h e XPS and IR-spectroscopy measurments.

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