bunshah - mechanical properties of thin films

8/4/2019 Bunshah - Mechanical Properties of Thin Films

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3 M e c h a n i c a l p r o p e r t ie s o f t h in f ilm s3 .1 M e c h a n i c a l p r o p e r tie s o f P V D f i l m sR F B u n s h a h , Engineering M aterials De partmenL University o f Cal i fornia, Los Angeles. CA 90024. U.S.A.

The me ch an ical propert ies o f thin f i lms are inf lue nce d by the ir structure,s, stability, inter na l stressesan d th ickness w hich m akes the understand/ng of the m echa nica l behavior a com plex problem.Thick f ilms o f meta ls and a l loys seem to fo l low the same, wel l -estab l ished t rends in s tructure an dpropert ies as bulk mater ia ls produ ced by m ore co nvent ional w roug ht techniques. The state o funderstanding of the m echa nica l behavior o f th ick f i lms of re fractory com pounds is s t / / / in i tsin fancy an d mu ch work rem ains to be d one for th is very impo rtant c lass of materia ls .

I n t r o d u c t i o nT h i s p a p e r r e v i ew s t h e c u r r e n t s t a t u s o f t h e m e c h a n i c a l p r o p e r -t i e s o f f i lm s p r o d u c e d b y t h e P h y s i c a l V a p o r D e p o s i t i o n ( P V D )p r o c e s s e s o f e v a p o r a t i o n , i o n p l a t i n g a n d s p u t t e r i n g . T h e t h i c k -h eS S o f t h e s e f i l m s ra n g e s f r o m 1 00 , ~ t o m i l l i m e t e r s a n d t h e y a r eu s e d i n a v a r i e t y o f d e c o r a t i v e a n d u t i l i t a r i a n a p p l i c a t i o n s n o to n l y a s c o a t i n g s b u t a s s e l f s u p p o r t e d s h a p e s , i . e . , s h e e t , f o i l,t u b i n g . A l t h o u g h ~ o r k i n th i s a r e a d a t e s b a c k m a n y d e c a d e s ,t h e b u l k o f t h e p a p e r s i n t h i s f i el d h a v e b e e n p u b l i s h e d o n l y i nt h e l a s t 2 0 y e a r s .

P V D t e c h n o l o g y i s v e r y v e r s a t i l e . I t e n a b l e s o n e t o d e p o s i tf i l m s o f v i r t u a l l y e v e r y t y p e o f i n o r g a n i c m a t e r i a l s - - m e t a l s ,a l l o y s, c o m p o u n d s a n d m i x t u r e s t h e r e o f - - a s w e l l a s s o m e o fo r g a n i c m a t e r i a ls . T h e d e p o s i t i o n r a t e s c a n b e v a r i e d fr o m1 0 t o 2 5 0 , 0 0 0 . ~ r a i n - 1 a n d e v e n h i g h e r . T h e h i g h d e p o s i t i o nr a t e s h a v e c o m e a b o u t i n t h e l a st 1 5 y e a r s w i t h t h e a d v e n t o fe l e c t r o n b e a m h e a t e d e v a p o r a t i o n s o u r c e s .

M u c h o f t h e e a r l y w o r k ( u p t o 1 9 63 ) w a s c a r r i e d o u t a t l o wd e p o s i t i o n r a t e s a n d d e a l t m o s t l y w i t h t h i n f i lm s . * T h e w o r k h a sb e e n a d m i r a b l y s u m m a r i z e d i n v a r i o u s w e l l - k n o w n t r e a ti s e s . 1 -6R e v i e w a r t i c l e s o n m e c h a n i c a l p r o p e r t i e s o f t h i n fi l m s h a v e b e e nw r i t t e n , ? -1 2 T h e w o r k o n t h i c k f i l m s a n d b u l k d e p o s i t s h a sm a t u r e d l a t e r a n d r e v i ew s o n i t h a v e b e e n g i v e n b y B u n s h a h 1 3 -t 6a n d b y P a t e n , M o v c h a n a n d D e m c h i s h i n 1~ w h o s u m m a r i z e dt h e w o r k d o n e a t t h e P a t e n W e l d i n g I n s t i t u t e u p t o 1 97 3. I na d d i t i o n t h e S o v i e t l i t e r a t u r e h a s n u m e r o u s r e f e r e n c e s t o t h ev e r y e x t e n s i v e w o r k o n t h i n a n d t h i c k f il m s b y P a l a t n i k a n dc o - w o r k e r s o f t h e K h a r k o v P o l y t e c h n ic I n st i t u te a l t h o u g h t h isa u t h o r c a n n o t c i t e a r e v i ew p a p e r f r o m t h i s s o u rc e .

T h e m e c h a n i c a l b e h a v i o r o f t h i n f i l m s is q u i t e d i ff e r e n t f r o mt h a t o f t h e b u l k a n d i s v e r y m u c h g o v e r n e d b y t h e m i c r o s t r u c -t u r e , i m p u r i t y a n d i m p e r f e c t i o n c o n t e n t w h i c h i n t u r n g o v e r n st h e r e s i d u a l s t r e s s i n t h e f il m . I n f a c t s o m e o f t h e i n c e n t i v e i nt h e p a s t f o r t h e e x t e n s i v e s tu d i e s o n t h i n f i l m s a r e t h e v e r y h i g hs t r e n g t h s a s c o m p a r e d t o c o l d w o r k e d b u l k m a t e r i a l a n d t h ei m p l i e d p r o m i s e f o r t h e d e v e l o p m e n t o f h i g h s t re n g t h m a t e r i a l s.T h i s h i g h s t r e n g t h w a s a t t r i b u t e d i n m o s t c a s e s t o t h e h i g hl e v el s o f i m p e r f e c t i o n s a n d o f r e s i d u a l s t re s s ; n u m e r o u s m e c h -

* T h e th ic k n e s s l imi t s f o r th in a n d th ic k f i lms a r e s o me wh a t a r b i t r a r y .Thin f i lms represen t th ickness up to 10 ,000 ,IL and th ick f i lms f rom1 0 ,0 0 0 , ~ a n d h ig h e r . T o d a y , a n o th e r v ie wp o in t i s t h a t a f i lm c a n b ec o n s id e r e d th in o r th i c k d e p e n d in g o n wh e th e r i t e x h ib i t s s u r fa c e - l ik ep r o p e r t i e s o r b u lk - l ik e p r o p e r ti e s .

a n i s m s a r e c i t e d i n t h e l i t e r a t u r e f o r t h e r e s i d u a l s t r e s s . T h e s ed e d u c t i o n s a r e o f t e n s p e c u l a t i v e b e c a u s e t h e m e c h a n i c a lp r o p e r t i e s o f t h i n f i l m s a r e g e n e r a l ly d e t e r m i n e d o n f i lm s c o n -d e n s e d o n s u b s t r a t e s h e l d a t l o w t e m p e r a t u r e s w h e r e a s t h est ructure is s tudied on f i lms condensed a t h igh temperatures. 9As the f i lm gets th icke r , the res idual s t ress level decreases andthe mechan ica l p roper t ies a re very s im i la r t o t hose o f t h ickf i lms o r bu lk condensates . I t shou ld a lso be po in ted ou t t ha tmos t o f t he mechan ica l p roper t ies have been s tud ied on f i lmsdeposi ted by eva pora t ion in h igh vacuum fo r t he s imp le reasontha t ion p la t ing o r spu t te r ing b r ing in to p lay o ther p rocessvar iables, such as the presence of a s igni f icant ion densi ty inthe va po r phase, e lect r ic al ly b iased subst rates, etc., which af fectthe s t ruc tu re , im pu r i t y con ten t a nd res idua l s t ress leve lsmarked ly and make the cor re la t ion be tween s t ruc tu re andmechan ica l p roper t ies more d i f f cu l t .As a precurso r to the d iscussion o n mech anical proper t ies,i t behooves us to unders tand the m ic ros t ruc tu re o f depos i tedf i lms .M i c r m t n c t u r e o f P V D c o n d e m a t e sP V D c o n d e n s a t e s d e p o s i t a s s i n g le c ry s t a l fi l m s o n c e r t a i nc r y s t a l p l a n e s o f s i n g l e c r y s t a l s u b s t r a t e s , i . e . b y e p i t a x i a lg r o w t h l S ; o r i n t h e m o r e g e n e r a l c a s e t h e d e p o s i t s a r e p o l y -c r y s t a l l i n e . I n t h e c a s e o f f i l m s d e p o s i t e d b y e v a p o r a t i o nt e c h n i q u e s , t h e m a i n v a r i a b l e s a r e ( 1 ) t h e n a t u r e o f t h e s u b s t r a t e( 2 ) t h e t e m p e r a t u r e o f t h e s u b s t r a t e d u r i n g d e p o s i t i o n , ( 3 ) t h er a t e o f d e p o s i t i o n a n d ( 4 ) t h e d e p o s i t t h i c k n e s s . C o n t r a r y t ow h a t m i g h t b e i n t u i t i v e l y e x p e c t e d , t h e d e p o s i t d o e s n o t s t a r to u t a s a c o n t i n u o u s f i l m o n e m o n o l a y e r t h i c k a n d g r o w .I n s t e a d , t h r e e - d i m e n s i o n a l n u c l e i a r e f o r m e d o n f a v o r e d s i t e so n t h e s u b s t r a t e s , e . g . c l e a v a g e , s t e p s o n a s i n g l e c r y s t a l s u b -s t r a t e , t h e s e n u c l e i g r o w l a t e r a l l y a n d i n t h i c k n e s s ( t h e s o - c a l l e dg r o w t h s t a g e ) u l t i m a t e l y i m p i n g i n g o n e a c h o t h e r t o f o r m ac o n t i n u o u s f i l m . F i g u r e 1 s h o w s t h e g r o w t h o f g o l d f i l m o nr o c k - s a l t . T h e a v e r a g e t h i c k n e s s a t w h i c h a c o n t i n u o u s f i l mf o r m s d e p e n d s o n t h e d e p o s i t i o n t e m p e r a t u r e a n d t h e d e -p o s i t i o n r a t e ( b o t h o f w h i c h i n f l u e n c e th e s u r f ac e m o b i l i t y o ft h e a d a t o m ) a n d v a r i e s f r o m 1 0 A f o r N i c o n d e n s e d a t 1 5 K t o1 0 00 A f o r A u c o n d e n s e d a t 6 0 0 K . O n c e a c o n t i n u o u s f i lm h a sf o r m e d , t h e s u b s e q u e n t e v o l u t i o n t o t h e f i n a l s t r u c t u r e o f t h et h i n fi l m is p o o r l y u n d e r s t o o d a t p r e s e n t . I t u n d o u b t e d l y d e -p e n d s o n t h e f a c t o r s m e n t i o n e d a b o v e w h i c h i n t u r n i n f l u e n c et h e p r i m a r y v a r i a b l e s o f n u c l e a t i o n r a t e , g r o w t h r a t e , a n d

Vacuum/volume 27/num ber 4. Pergam on Press/Printed in Great Bri ta in 353


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R F B u n s h a h : Me chan ica l p r ope r t i es o f P V D f i lmss u r f ac e m o b i l i t y o f t h e a d a t o m . T h e p r o b l e m h a s b e e n t a c k l e db y V a n d e r D r i f t ' 9 a n d i s a l s o t h e s u b j e c t o f a c u r r e n t l y u n -p u b l i s h e d p a p e r b y T h o r n t o n . z

T h e m i c r o s t r u c t u r e a n d m o r p h o l o g y o f t h i c k s i n g l e p h a s ef i l m s h a v e b e e n e x t e n s i v e l y s t u d i e d f o r a w i d e v a r i e t y o f m e t a l s ,a l l o y s a n d r e f r a c t o r y c o m p o u n d s . T h e s t r u c t u r a l m o d e l w a sf ir st p r o p o s e d b y M o v c h a n a n d D e m c h i s h i n , z l F i g u r e 2 a n dw a s s u b s e q u e n t l y m o d i f i e d b y T h o r n t o n z 2 a s s h o w n i n F i g u r e 3 .M o v c h a n a n d D e m c h i s h i n ' s d i a g r a m w a s a r r i v e d a t f ro mt h e i r s tu d i e s o n d e p o s i t s o f p u r e m e t a l s a n d d i d n o t i n c l u d e t h et r a n s i t i o n z o n e o f T h o r n t o n ' s m o d e l , Z o n e 7", w h i c h i s n o tp r o m i n e n t i n p u r e m e t a l o r s i n gl e p h a s e a l l o y d e p o s i t s b u tb e c o m e s q u i t e p r o n o u n c e d i n d e p o s i t s o f r e f r a c t o r y c o m -p o u n d s o r c o m p l e x a l l o y s p r o d u c e d b y e v a p o r a t i o n a n d i n a l lt y p e s o f d e p o s i t s p r o d u c e d i n t h e p r e s e n c e o f a p a r t i a l p r e s s u r eo f i n e r t o r r e a c t i v e g a s , a s in s p u t t e r i n g o r i o n p l a t i n g p r o c e s s e s .

T h e e v o l u t i o n o f t h e s t r u c t u r al m o r p h o l o g y i s a s f o l l o w s , a st h e w r i t e r s e e s i t t o d a y :

A t l o w t e m p e r a t u r e s , t h e s u r fa c e m o b i l i t y o f t he a d a t o m s i sr e d u c e d , a n d t h e s t r u c t u r e g r o w s a s t a p e r e d c r y s t a ll i t e s f r o m al i m i t e d n u m b e r o f n u c l e i . I t i s n o t a f u l l d e n s i t y s t ru c t u r e b u tc o n t a i n s l o n g i t u d i n a l p o r o s i t y o f t h e o r d e r o f a f e w h u n d r e d

~ n g s t r 6 m s w i d t h b e t w e e n t h e t a p e r e d c r y s t a l li t e s . I t a l s o c o n -t a i n s a h i g h d i s l o c a t i o n d e n s i t y a n d h a s a h i g h l e v e l o f r e s i d u a ls t re s s. S u c h a s t r u c t u r e h a s a l s o b e e n c a l l e d ' B o t r y o i d a l ' a n dc o r r e s p o n d s t o z o n e 1 i n F i g u r e s 2 a n d 3 .

A s t h e s u b s t r a t e t e m p e r a t u r e i n c r e a s e s , t h e s u r f a c e m o b i l i t yi n c re a s e s a n d t h e s t r u c t u r a l m o r p h o l o g y f ir st t r a n s f o r m s t ot h a t o f Z o n e 7", i . e. t ig h t l y p a c k e d f i b r o u s g r a i n s w i t h w e a k g r a i nb o u n d a r i e s a n d t h e n t o a f u ll d e n s i t y c o l u m n a r m o r p h o l o g yc o r r e s p o n d i n g t o Z o n e 2 ( F i g u r e 3 ).

T h e s i ze o f t h e c o l u m n a r g r a i n s i n c re a s e s a s t h e c o n d e n s a -t i o n t e m p e r a t u r e i n c r e a . ~ . F i n a l l y , a t s t i ll h i g h e r t e m p e r a t u r e s ,t h e s t r u c t u r e s h o w s a n e q u i a x e d g r a i n m o r p h o l o g y , Z o n e 3 .F o r p u r e m e t a l s a n d s i n g l e p h a s e a l l o y s , T I i s t h e t r a n s i t i o nt e m p e r a t u r e b e t w e e n Z o n e | a n d Z o n e 2 a n d 7 "2 i s t h e t r a n s i t i o nt e m p e r a t u re b e t w e e n Z o n e 2 a n d Z o n e 3 . A c c o r d i n g t o M o v c h a na n d D e m c h i s h i n ' s o r i g i n a l m o d e l , 22 T I i s 0 . 3 T ,, f o r m e t a l s , a n d0 . 2 2 - 0 . 2 6 7"= f o r o x id e s ; wh e r e a s 7 ", i s 0 . 4 5 - 0 . 4 7 ", f o r b o th a ss h o w n i n F i g u r e 4 . ( 7 " . i s t h e m e l t i n g p o i n t i n K . )

T h o m t o n ' s m o d i f i c a t i o n s h o w s t h a t th e t ra n s i t i o n t e m p e r a -t u r e s m a y v a r y s i g n if i c a n tl y f r o m t h o s e s t a t e d a b o v e a n d i ng e n e r a l s h i f t t o h i g h e r t e m p e r a t u r e s a s t h e g a s p r e s s u r e i n t h es y n t h e s i s p r o c e s s i n c r e a s e s.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 1 . Sequence of mic rograp hs i l lus t ra t in g the e ffect o f increas ing dep osi t th ickness o f go ld on rocks a l t . 8000. s3 5 4


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R F Bunshah: M e c h a n i c a l p r o p e r t i e s o f P V D f i lm sZ o n e I Z o n e 2 Z o n e 3~ ~ q : ~. . - . ; ; ~ ; =' . ' . : ' . . - . . . .%~,P," $ " . . ", . .: . . ;- . : .- . : . - . . . . . j. . : . . i ': ~ " . 3 - . . .

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T, T 2T e r n p e r o t ' u r e , ,

Z o n e I Z o n e 2 Z o n e 3M e t o l s < 0 3 T ;~ 0 . 3 - 0 4 5 T , ~ > 0 . 4 5 T ~O xiO es < 0 . 2 6 T ~ 0 2 6 - 0 4 5 T ~ > 0 4 5 T ' ~

F i g u r e 2 . S t r u c t u r a l z o n e s i n c o n d c n s a t e s . =~TRAN SITION STRUCTURECONSISTINGOFDENSELYPACKEDFIBROUS GRAINSPOROUSSTRUCTURECONSISTINGOF TAPEREDCRYSTA LLITES SEPARATED

BY VOIDS ~ 3 1 1 ~

ARGONPRESSURE(rnTorrlFigure 3. Structural zones in condensates. 2~

COtU /i~AR GRAINS

~ ~ RECRYSTALLIZEDGRAIN STRUCTURE~ " ~ '

~ ' I = " = . 7 . ~ : ' . . : " ~ '. ': " " 7 . % ~ ~ , : " % ~ . ~ . ~ . [ A ':,f',[~,.~=~:-..~;.:.,.- .=... ' : . . . .~.,.~D .6L5 SUBSTRATETEMPERATURE T/TM)

It should be emphasized that :I. The transition from one zone to the next is not abrupt but

smooth. Hence the transition temperatures should not heconsidered as absolute but as guidelines.

2. All zones are not found in all deposits. For example,Zone T is not promi nent in pure metals but becomes morepronounced in complex alloys, compounds or in depositsproduced at higher gas pressures. Zone 3 is not seen veryoften in materials with high melting points.

Figure 4 shows scanni ng electron micrographs of Zones 1, T,and 2 in TiC deposits. Other examples may be seen in the illus-trations in ref ~a-16Most thick deposits exhibit a strong preferred orientation(fiber texture) at low deposition temperatures an d ten d towardsa more random orientat ion with increasing deposition tempera-ture. Figure 5 shows the evolution of a large grained columna rmorphology in a Be deposit from a much larger num ber of finegrains which were originally nucleated on the substrate. Asgrowth proceeds, only those grains with a preferred growthdirection survive, presumably due to considerations of theminimi zation of surface energy.

Mechanical property determinationA number of testing techniques have been used to determinethe strength properties of t hin films. They include the high speedroto r test 23 the bulge test 2`-2a micr otensil e testing machi nes ofthe 'soft 29-32 a nd the 'h ard ' categories a3-36 and even fixtures

which can be operate d in the electron microscope, aT'as Hoff-man ~ has reviewed the test t echniques and the reader could dono better than to read Hoffman's article or the original refer-ences. The basic handling problem encountered with the prep-aration and mechanical property testing of thin film specimensis much less severe with thick films for which many of thestandard test specimens, machines and techniques can hereadily used. Therefore, the spectrum of mechanical propertiesmeasured on thick films is much broader than with thin films.

M e c h a n i c a l p ro p e rt ie s o f th i n f il m sT h e t e n s i l e p r o p e r t i e s o f t h i n f i l m s h a v e b e e n r e v i e w e d . 9 , t o . 3 6, z ~A s H o f f m a n t c o n c lu d e s , t h e d a t a r e p o r t e d a r e n o t v e r y c o n -s i st e n t e ve n o n t h e s a m e m a t e r i a l . T h e r e a d e r i s a d v i s e d t oc o n s u l t t h e r e f e r e n c e s f o r d e t a i l s .

I n g e n e r a l , t h e o b s e r v e d s t r e n g t h o f v a p o r - d e p o s i t e d m e t a lf i l m s c o n s i s t s o f t h r e e p a r t s :O'OBS = O 'Bulk J r O ' l m p e r f c c l i o n s ~ O-Thickne~swhere aau~k is the inherent strength level of bulk polycrystailinematerial in the anne aled state, al,,,,,f,c,~,, , is the cont rib uti ondue to point and line defects resulting from the depositionprocess in excess of those normally found in the bulk annealedstate an d oth~=k,,,, is the con tri buti on arising from the smallestdimen sion of the film and its limiti ng effect o n grai n size suchthat dislocation multiplicati on and migration are impeded. ~ITable I gives the strength properties of thi n films of some metalsand compar es them to bulk values. 10 In man y cases thestrengths are about 200 times those of annealed bulk samplesand 3 to 10 times those of hard drawn samples. The tensilestrength values are given numerically as well as by fractions ofthe shear modulus. The ductility of the high strength films isvery limited which is similar to the behavior of high strengthfibers or whiskers. A principal point of contention is whetherthe ult imat e tensile strength is a f uncti on of the film thickness ornot. The discrepancy also appears to he dependent on the testmethod used, i.e. between the bulge test and tensile test. Inmany cases it appears that the strength decreases as the filmthickness increases from approxi matel y the 2(X)-300 A. range toabo ut 2000--4000 A range. At the greater t hickness the strengthis abou t the same as that o f heavily worked bulk material. Thereare several papers relating the strength properties of thin filmsto t he 'crystallite size' and 'block struct ure' as influenced by thedeposition temperature, stress, recovery and recrystallizationprocess. *-49 One manifestation of this is the phenomenon ofcreep or plasticity in room temper ature tensile tests as exhibitedby an irreversible initial loading curve but almost reversibleunl oadi ng and reloadi ng curves as long as the previous stresslevel is not exceeded. An example of this is shown in Figure 6from Neugebauer3 as the change in slope of the stress--straincurve. The poss ibility of this change in slope being related to anelastically soft measurement or to creep in the cement of thegrips altogether be discarded.

Long term creep rates have been measured and for gold theyvary from 10 -7 to lO"-4 min -~ depend ing on load, dimens ionsand the a moun t of prestrain. 3 The estimates of the relativeelastic and plastic extension at fracture vary from completelyelastic to an almost even mixture of elastic and plastic deforma-tion.Fracture in ductile gold single crystal filmsa6 results from alocalized plastic deformati on with r esultant t hinning of the film

3 5 5


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R F B u n s h a h : Mech anical propert ies o f PVD f i lms

O l I ~ I I T~ I u n l i ~ l C ly ~ ' ~,' - -. ..~ . , -

. ' . . . : { ' , ; ,~ , . ~ ' ~ , ; '

F R A C T U R ECR OB S~CTION D E P O S I T I O N M I C R O N A R D N I F ,B $T E M P E R A T U R E I r~ I L O A D l O I N

52 O 3OOOZ O N E.11=o

Z O N E T

~4 i ! " '~,

: ' { l ~ i~; - - i ' " ~ O O 0 t k ~ oZ O N E 2

_ ! Z O N E 3Figure 4. Structure and m icrohardncss of Ti C d eposits at various sub strate temperatures. M

and a r ise in st ress level . Eventual ly the smal ler cracks formedin th i s man ner jo in to cause f rac tu re . Th e d is loca t ions necessaryf o r t h e d e f o r m a t i o n a r e n o t t h e g r o w n - i n d i s l o c a t io n s b u t t h o s ew h i c h n u c l e a t e a n d m u l t i p l y i n d i s c o n t i n u o u s re g i on s . M o s to b s e r v a ti o n s s h o w n o n e c k i n g p r i o r t o f r a c tu r e . Th e m a x i m u mstress appears to cor respo nd to tha t needed to p ropagate c racksf rom f laws ex is t ing in the specimen, in po lyc rys ta l l i ne n icke l ,the f ra cture is the 'c lean-c leavag e' type. 3~

M e d m ~ c = l ~ o f t l d c k c o m l e ~ a t e s a n d I m l k d e p z ~ t sTab le 2 l i s t s the mechan ica l p roper t ies o f th i ck depos i t s o f -meta ls , a l l oys , re f rac to ry compounds and lam ina ted s t ruc tu res .In ma ny cases , the me chan ica l tes t da ta a re qu i te ex tens ive

sho w ing y ie ld s t reng th , u l t imate tens i le s treng th , hardness andd u c t i l i t y a s a f u n c t i o n o f g r a i n s iz e , d e p o s i t i o n t e m p e r a t u r e a n dtes t tempera tu re . One o f the fea tu res o f the d a t a is that theproper t ies o f th i ck depos i t s o f meta ls and a l loys a re very s im i la rt o t h os e o f w r o u g h t m a t e r i a ls w h i c h a r e p r o d u c e d b y t h e c o n -v e n t i o n a l p ro c es se s o f m e l t i n g , c a s t in g , m e c h a n i c a l w o r k i n g a n dh e a t t r e a t m e n t .

We w i l l cons ider each type o f mater ia l separa te ly s ince thebeh av io r o f meta ls and a l loys is vas t l y d i ffe ren t f rom tha t o fr e f r a c t o r y c o m p o u n d s .The ear l y w ork in th i s a rea was tha t o f Bunsha h, 53 .s4Bunsha h a nd Jun tz "*s and Sm i th ~6 wh o depos i ted th i ck f i lmsof Be, T i and Cu respec t i ve ly and measured me chan ica lp roper t ies . In 1965, Pa la tn ik and co-wo rkers pu b l i shed a paper

35 6


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R F Bunshah: Mecha nical propert ies of PVD f i lmsTable ! . Strength properties of thin f i lms.

Maximum tensi le strengthShear Strain at Thickness-Material Structt=re kg/mm z modul us* fracture, ~/o depend ent ReferenceAu Bulk hard -draw n 28? G/114 ~.(l I I) cryst al film 81 G/36 1.2 No 36(100) cryst al film 27 G/I l0 0.5 Yes 25(l l0 ) (l I I) polycrystall ine lilm 49 G/59 I No 30Polycrystalline film 55 G/54 0.7 Yes 24(100) cryst al film 26 G/ I 15 3.5 No 32Polycrystalline film 32 G/92 2.3 No 32Ag Bulk hard -dra wn 371" G/75 - - - -Polycrystallin e fihn 59 G/47 0.7 Yes 24Polycrystalline film 42 G/68 0.3-0.4 - - 50Cu Bulk hard -dra wn 49 G /98 - - - - - -Polycryst alli ne film 93 G/51 1.8 Yes 51Polycrystalline film 88 G/54 - - No 37Rolled foil 19 G/256 10-15 No 52Ni Bulk cold-rol led 1251" G/67 -- -- - -Polycrystalline film 2 I0 G/40 1.8 Yes 3 IAI Bulk cold- rol led 16"t" G/171 - - - -Polycrystalline film 42 G/66 0.5-0.8 50

* Shear moduli from AlP Handbook , t957.1" Bulk tensil e stren gth from Handbook o f Chemis try and Phys ics , 42nd ed.,Fracture strain not quoted for hulk material. 1961.

Figure 5. Phot omicro graph of a Be deposit showing the evolution oflarge columnar grains.i !

's =~ GoldI=J 2 0Z)..QC~9*=l 1.0n -)..

I0 0 5 1 .0S T R A I N P E R C E N T

Figure 6. Typical s tress -stra in curve for thin film. s

on mechan ica l p roper t ies o f A I conden sates : ~ I t i s imposs ib leto review in detai l a l l the papers. The per t inent data are shownin Table 2 and the discussion below wi l l concent rate on thehighl ights.Meta l s and a l l oys . Movchan and Dcmchish in s tud ied thetensi le proper t ies and microhardness of Ni , Ti and W con-densates produced at var iou s depos i t ion temperatures. Notensi le tests were per form ed on specimens deposited in Zon e ](Figu re 2) . Tests on specimens deposited in Zon e 2 showed highs t rength and l ow duc t i l i t y a t l ow depos i t i on tempera ture . Thest rength decreased and the du ct i l i ty increased wi th dep osi t iontempe rature. The st rength a nd d uc t i l i ty values of specimensdeposited i n Zo ne 3 showed app rox ima te l y the same va lues asfor r cc rys ta l l i zed specimens produced f rom wrough t ma ter i a l,The microhardness var i a t i on w i th depos i t i on tempera ture fo rNi , Ti and W is shown in Figure 7. The tapered crystal l i temorpho logy i n Zone I showed a h igh hardness much greaterthan th at o f annealed m etal . The hardness decreased rap idlyw i th i nc reas ing depos i t i on tempera ture to a fa i r l y cons tantva lue fo r Zone 3 morph o logy wh ich cor responds to the hardnessof recrystallized metals.

WE guo [ ~ oE 72oI~. 58o

4 2 0 -

T i~ , 0 0 / ' ~ ' I ' .

~ EE4 8 0 c ~

~2 0

1 I2 0 0 4 0 0 6 0 0 8 0 0 I 0 0 0 ) 2 00 14 0 0 ) 6 0 0B o s e t e m p e r o t u r e C

Figure 7. Variat ion of microhardness with deposi t ion temperature ormetals.2.3 5 7


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R F Bunshah: Mech an i ca l p r oper t ies o f P V D f i lms

Table 2. Mecha nica l proper t ies of th ick f i lms o r b u lk condensates.0 .2 ~ , Y i e l d U l t i ma t e Depo s i t ion Gr a i n Tes tstress tensile 5/. Elong Micro hardn ess temp size Thickness temp Refer.Material (kg/mm 2) streng th (or ~ RA) (kg/mm') (C) (tzm) (~m) (C) ence

AI 200 200 40 25 57160 30080 4OO8 Kn oop at 250-350 1-20.5 g toadCu

25 6715 1 4--10 25 6328 0.740 0.145 0.0718-22 35 400-800 1000 25 17240 120 > 15 25 68170 18050 2.38 3-20 25 6916 0.27(annealed 500C)60 0.1 0.5 25 70

40 0.6 3-5Ag 10 1 5-20 25 6335 0.1Fe 66-72 250 20 25 7145 46 4 120 400 1000 25 7220 35 20 90 55015 25 18 75 700Be 140 0.I 24 0( Kn op p) 350---425 75-100 25 72281 0.3 215 480--550316 0.45 168 625-685295 1.0 170 760--79062 (bend test) >4 (ben d test) 100 1000 25 5447 (bend test) >5. 2 (bend test)Ni 115 0.3 0.2 0.2 -2 25 73

66-74 250 400-420 20 25 74

Ti

M o

NbVW

450 260600 22096.6 554109 425104 329125 26091

129 338 39(20) 26 275135 336 32(20) 19 375155 366 35(21) 12.7 375247 403 21(21) 3.7 375140(m elt ed 407 44(30) 18 357and wrought)

25 59

138 0.6 2.6 25 27250 620 I000 25 21400 420600 38028 20 400 1000 25 1738 12 800189 295 25(66) 800 32 250 25 58225 302 20(38) 600 8 250 25436 471 3(25) 450 I 250 25189 (melte d 302 40f61 ) 50 250 25and wrought) 560 200200 400130 500

1000 25 21

100-250 25 75200300 76

300 76300 76

1000 25 211000 251000 25

280--420 20141)-280 3514 19 (5.3 191 990 53024 28 (0.8) 169 704 8538 44 (1.0) 186 804 1919 7.3 112 745 I037 22 I 15 540 0.7

720 600460 1000300 10003 5 8


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R F B u n s h a h : Mec hanica l properties of PVD f i lmsTable 2 . - - c on t i n ued

0. 2~ Y ie ld U l t imate Deposi ti on Gra in Tes ts t r e ss t e n s il e ~ E l o n g M i c r o h a r d n e s s t e m p s i ze T h i c k n e s s t e m p R e f e r -M a t e r i a l ( k g / m m 2 ) s t r e n g t h ( o r % R A ) ( k g / m m z ) ("C) (o ,m) ( / ,m) CC ) en c eN i - 2 0 C r 3 3 7 5 4 0 2 6 ( 2 7 ) 8 0 9 5 0 1 3 3 7 5 2 5 6 05 7 7 7 8 0 2 1 (2 6 ) 1 1 2 7 8 0 2 .6 3 7 5 2 5752 871 18(19) 131 680 1 .8 375 25

1195 1223 6(8) 180 427 0.5 375 25393 (melted 569 37(31 ) 78 10.4 325 25and w rought )2 5 4 9 2 5 (2 1 ) 9 5 0 1 3 3 7 5 1 0 0 04 0 .9 6 0 5 3 (4 1 ) 6 8 0 1 .8 3 7 5 1 0 0 0

T i - 6 A I - - 4 V 9 7 0 - 1 1 9 5 1 0 6 8 - 1 1 9 5 1 - 1 2 7 9 2 5 6 58 0 N i-2 0 C u 3 5 --4 5 8 -2 5 4 (X) --80 0 3 7 5 1 0 0 0 1 75 0 N i - 5 0 C u 4 0 - 5 5 5 - 2 0 4 0 0 - 8 0 0 3 75 1 0 002 0 N i - 8 0 C u 2 7 - 4 2 10- 30 4130-800 375 10008 0 N i - 1 6 F e 1 80 6 5 0 2 0 0 2 5 7 4( p e r m a l l o y ) 1 5 0 2 5 0 4 0 0 2 5A 1 2 0 3 3 8 0 4 0 0 3 0 0 2 5 2 1

8 0 6 0 0 3 0 0 2 52 0 0 1 0 0 0 3 0 0 2 51000 1400 300 255 0 0 - 8 0 0 I 1 0 0 3 0 0 2 5 8 1Z r O 2 4 5 0 4 0 0 3 0 0 2 5 2 13 5 0 6 0 0 . 3 0 0 2 540 0 11300 300 251 0 0 0 1 4 0 0 3 0 0

2 4 8 3 8 4 1 2 0 3 .2 1 0 02 2 6 2 5 6 2 1 0 5 1 0 02 1 5 3 3 1 3 0 4 8 1 0 02 0 8 3 2 0 4 1 6 1 4 1 0 02 0 5 3 6 0 5 3 8 2 1 1 0 0198 502 721 58 1009 6 0 - 1 9 6 0 7 5 0700--2015 11003 0 0

1 9 0 7 - 2 4 4 01 8 0 0 - 2 4 0 03 5 0 0 - -4 0 0 02 7 1 02 9 5 52 9 5 54 1 1 04 1 6 02 4 0 02 5 0 0 - 2 8 0 02 7 0 0 - 3 0 3 02 3 5 02 3 0 0

Y 2 0 3

T i ~ OT i eS i O 2T a : CT a CS i C ( r f s p u t t e r )T i C ( A R E p r o c e s s)

Z rC( H f - 3 Z r ) CV CN b C

C u - N i l a m i n a t eC u - F e l a m i n a t e 3 5 - 7 0C u - N i l a m i n a t eC u - F e l a m i na t eN i - F e l a m i n a t eN i - S i O

T i - T i C

L A M I N A T E S

5 0 05 0 0

10

2 .65 2 0 5 07 3 0 5 08 3 0 5 01080 501 1 2 0 5 05

5 5 0 5 0 - 7 55 5 0 5 0 - 7 55 5 0 5 0 - 7 55 5 0 5 0 - 7 5

3 5 - 5 5 1 31 1 0 4 (3 0 -8 0 0 2 4 0 -3 6 080 1 .8 300125 0 .88 150150 0 .45 1501 5 0 3 0 0105 3009 5 3 0 08 0 2 0 025 1 1.8 500

21 5 - 2 50. 10 .0 40 .0 42 02 02 02 0

2 5 0

2 5 7 82 52 52 52 52 52 5 8 22 52 5 8 32 5 8 42 52 5 8 52 5 7 92 52 52 52 52 5 8 0

9 2

2 52 52 525252 52 0 04 0 06 0 0

9 5

8 6878 8

8 9

90

35 9


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R F 8 u n s h a h : Mechan ical properties of PVD f i lmsB u n s h a h a n d c o - w o r k e r s s t u d i e d t h e e f fe c t o f d e p o s i t i o n

t e m p e r a t u r e o n t h e g r a i n s iz e , te n s il e p r o p e r t i e s a n d h a r d n e s s o fT i ,S S . s s N i , S e N b , V , M o 7 6 a n d N i - 2 0 C r 6 a l l o y s f o r d e p o s i t sm a d e i n Z o n e s 2 a n d 3 . T h e y f o u n d t h a t i n c r e a si n g d e p o s i t i o nt e m p e r a t u r e p r o d u c e d l a r g e r g r a i n s iz e , lo w s t r e n g t h , h i g h e rd u c t i l i t y , a n d l o w h a r d n e s s . E v e n a t t h e l o w e s t d e p o s i t i o nt e m p e r a t u re i n Z o n e 2 , t h e d u ct i li t y w a s g o o d ( > 2 0 % R A f o rI t , m g r a i n d i a m e t e r T i a t a y i e l d s t r e n g t h o f 5 6 , 0 0 0 p s i ).M o r e o v e r , t h e y f o u n d t h a t b o t h t h e y i el d s t r e n g t h a n d h a r d n e s sv a r i e d a s t h e i nv e r s e s q u a r e r o o t o f g r a i n d i a m e t e r , i . e. fo l l o w e dt h e H a l I - P e t c h r e l a t i o n s h i p ,6 t , 6 , w h ic h i sa . = a o + kd- t /2w h e r e ,7 ,, i s t h e y i e l d s t r e n g t h ; d i s t h e g r a i n d i a m e t e r a n d ;S o , k a r e c o n s t a n t s . F i g u r e 8 s h o w s a n e x a m p l e o f t h i s r e l a t i o n -s h i p f o r N i - 2 0 C r a l l o y .

G r o i n d i o m e t e r , /~mtO 5 2 I O 52OO I I I 1 l

1 60

v~..-120 --

~_ 8oo _>.

~'~:~ o Deposited4 0 o W i l c o x eta/.~ f W e b s t e r jo ,b 2o 30 ~ ~o

" 1 / 2 r am- I / 2G r o l fl d i a m e t e r ,Figme g. Var ia t ion of y ie ld s t r ength w ith gra in- s ize for Ni-2 0 Cr .""

F o r a l l t h e s e m e t a l s a n d a l l o y s t h e y i e l d s t r e n g t h , d u c t i l i t ya n d h a r d n e s s v a l u e s c o r r e s p o n d t o t h o s e o f t h e sa m e m a t e r i a l sp r o d u c e d b y c a st i n g , m e c h a n i c a l w o r k i n g a n d r e c r y s ta l l i z a ti o n .T h e v a r i a t i o n o f y i e l d - s t re n g t h a n d h a r d n e s s w i th g r a in - s i ze ,i .e . H a l I - P e t c h t y p e r e l a t i o n s h i p s w e r e a l s o v e r y s i m i l a r b e -t w e e n t h e d e p o s i t e d a n d w r o u g h t m a t e r i a l s , s m a l l v a r i a t i o n sb e i n g a s c ri b a b l e t o d i f fe r e nc e s in g r a i n m o r p h o l o g y a n d p r e -f e r re d o r ie n t a t i o n s . T h e N i - 2 0 C r a l l o y sh o w e d g o o d s t r e n g tha t 1 00 0 C a n d a l s o o b e y e d t h e H a l l - P e r c h r e l a t i o n s h i p .

T h e H a l I - P e t c h r e l a t i o n s h i p i s a l s o o b e y e d b y t h i c k f il m s o fC u a n d A g t o g r a i n - s i z e s a s s m a l l a s 0 .0 5 t ~m a s s h o w n b yN e n i o t o , J u m b o u a n d S u t o . 63 T h u s , t h e se t h i c k d e p o s i t s b e h a v ea s t r u e e n g i n e e r i n g m a t e r i a l s .

C h a m b e r s a n d B o w e r 6'~ s t u d i e d t h e m e c h a n i c a l p r o p e r t i e s o f1 8- 8 s t a i n l e s s s t e e l , g o l d a n d m a g n e s i u m a n d s h o w e d t h a t t h e i rt e n s i l e p r o p e r t i e s w e r e v e r y s i m i l a r t o t h e i r w r o u g h t c o u n t e r -p a r t s .

S m i t h , K e n n e d y a n d B o e r i c k e 6s s tu d i ed the ( r, - i /9) typ eT i - 6 A I - 4 V a l l o y . T h e y s h o w e d t h a t t h e t e n s i le p r o p e r t i e s a r ev e r y s i m i l a r to t h e w r o u g h t m a t e r i a l e x c ep t f o r a m u c h s m a l l e rv a l u e in p e r c e n t e lo n g a t i o n d u e t o p r e m a t u r e o n s e t o f p l a s ti ci n s t a b i l i t y in a t e n s i l e te s t a t p i n h o l e s i n t h e d e p o s i t e d s a m p l e s .T h e b e n d d u c t i l i t y w a s h o w e v e r s u p e r i o r t o t h e w r o u g h tm a t e r i a l .

P a t o n , M o v c h a n a n d D e m c h i s h i n ~7 s t u d i e d t h e m e c h a n i c a l

proper t ies of d ispers ion-strengthened al loys. Fo r N i - N b Cal l oys , t he y ie ld s trength i ncreases w i th vo lum e f rac t i on o f t hedispersed ph ase and decreases wi th an increase of d epo si t iontempe rature which in tu rn increases the par t ic le s ize and inter -par t ic le spacing. They also studied the steady-state creep rateof N I -Z rO 2 dispers ion st rengthened al loys wh ich is very low ata v e r y h i g h t e m p e r a t u r e .

T h e s a m e a u t h o r s t7 a l so s h o w e d t h a t i t is p o s s ib l e t o p r o d u c et h i c k d e p o s i t s o f a l l t h e a l l o y s a c r o s s t h e C u - N i s y s t e m a n d t h a tt h e m e c h a n i c a l p r o p e r t i e s v a r y s y s te m a t i c a l l y w i t h c o m p o s i t i o na s w o u l d b e e x p e c t ed .

M o v c h a n , D e m c h i s h i n a n d K o o l u c k ~6 s t u d ie d F e , F e - N b C ,a n d F e - N i - N b C a l lo y s . T h e i r r es u lt s in d i ca t e th a t N b Ci n c r e a s e s t h e s t r e n g t h o f F e a t 2 5 a n d 700C. A l l o y i n g t h e F em a t r i x w i t h N i p r o d u c e s a d d i t i o n a l s t r e n g th e n i n g a t b o t h t e m -p e r a t u r e s t h u s s h o w i n g t h e p o s s i b i li t y o f c o m b i n i n g s o l i ds o l u t i o n s t r e n g t h e n i n g a n d d i s p e r s i o n s t re n g t h e n i n g .

R e f r a c t o r y c o m p o ~ K I sDepos i t s o f re f rac tory compound s , ox ides , n i t r ides and carb idesare very impor tan t f o r wear res i s tan t app l i ca t i ons i n i ndus t ry .Th ei r s t ructure and prope r t ies are st rongly dependent on thedepos i t i on process . Th e i r behav ior is very d i f fe ren t f rom meta l sand al loys. I t i s a lso very hard to measure the mechanicalproper t ies of ceramics by ten si le tests s im i lar to those used formeta l s and a l l oys because o f t he i r b r i t t l e na ture . A very goodtest to measure the f racture st ress of such br i t t le coat ings is theHe r tz ian f racture test which measures the f racture st ress and thesur face energy a t the f ractu re sur face. 7~ Colen and Bunshah 7sused to measure the f rac ture behav ior o f YzO ~ deposi ts o fvar ious grain s izes.

Figure 9 shows the var iat ion in microhardness wi th d eposi -t i on t em per a t u r e f o r A I z O 3 and Z r O 2 f r om t he w o r k o fuE 12OOE

tO00 --

o 'r~4 80 0

0~ ' 6 0 0

c 4 0 0 2o2 0 0_~ AL~O~:E

200 4 0 0 6 0 0 8 0 0 I 0 0 0 t200 1400 t 60CS u b s t r o t e t e m p e r 0 t u r e , C

Figure 9. V ariation of microhardness with deposi t ion temperature forAI203 and ZrO~. 2 'Movc han and D emch ish in , z ' shuw ing tha t t he beh av ior o fthese oxide deposi ts is qui te di f feren t in one respect f rom thatof metals (Figure 8) . The hardness fa l ls when the st ructurechanges f rom tapered c rys ta l l i tes (Zone I ) t o co lumn ar gra ins(Zone 2) as wi th metals. However , unl ike metals the hardnessincreases markedly as the deposi t ion temperature r ises f rom

0.3 T, , to 0.5 7" , . The a uthors a t t r ibu te th is to a m ore 'per fee t 'ma ter ia l produce at the higher depo si t ion temperatures due to' vo lume processes o f s i n te r ing ' . A s im i l a r hardness curve wasobta ined fo r Y 20 ~ deposit s. TM3 6 0


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R F B u n s h a h : M e c h a n i c a l p r o p e r t i e s o f P V D f i lm sFigure 10 from the work of Raghuram and Bunshah79 also

shows a very marked increase in microhardness of TiC depositson going from 0.15 7", (500 C) to 0.3 7", (1000' C). The hardnessincreases for the oxides and TiC with increasing deposi tiontemperature. Both these sets of results may be explained by thefollowing concept. Since the strength of ceramics is very

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o K H N . . . . . .. . .5 0 9 L o O O ........" " " I. .y . . '

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2 0 0 0 ] :0 5 0 0 J O 0 0 t S O 0S u b s t r e t e ' t e m p e r o t u r e , C

F i g u r e 1 0. V a r i a t i o n o f m i c ro h a r d n e ~ s w i t h d e p o s i t i o n t e m p e r a t u r ef o r T i C . ~

adversely effected by growth defects and at the higher deposi-tion temperatures, the occurrence of these defects is markedlyreduced, the hardness (or strength) increased very significantly.However, it should be noted that the absolute value of thehardness of the oxides is much lower than that of the carbides.Thus the possibility of a different explanation for the 'similar"behavior of these materials, i.e. the hardness increase withdeposition temperature needs to be investigated.

The hardness data on sputtered TiC a n d TiN coatings arequite similar to those produced by evaporation techniques?

LaminatesLaminate composites are very attractive because of the un iformproperties in the plane of the sheet. In comparison to mechani-cal methods of producing laminate composites, e.g. bondin g ofsheets, physical vapor deposition techniques are very suitedto the production of such composites particularly if each lamel-lae is to be very thin (---4).1 ~m) in ord er to improv e the str engthand toughness of the composite. It also gives us the opportun ityto have a high strength ceramic as one of the phases. Work todate has been very limited. In one investigation of the Cu -Nilaminates, no improvement in strength was foun d? 6 It is not a nideal system to investigate. In the Fe -C u sT'hs an d Ni- SiO s9composites, the strength increased significantly. The Ni-S iOsystem was notable for the fact that the composite retained itshigh strength up t o 700C, which is reminiscent of the dispersionstrengthened SAP alloys. This appears to be a most fruitfulfield for future research.

D a m p i n g capacityAs a final note, it may be mentioned that fine-grained films ofAI and Cu have been found to have a much higher damping

capacity owing to the relaxation processes associated with largeangle grain boundaries. Below 180 K, the damping is equal forsingle crystal an d polycrystalli ne film s? ~

S u m m a r y an d conclusionsPhysical Vapor Deposition (PVD) te~:hniques are a powerfulway to produce thin films, thick films and bulk deposits of avariety of materials. The mechanical properties of thin films areinfluenced by their structure, stability, internal stresses andthickness which makes the under sta ndi ng of the mechanicalbehavior a complex problem. Thick films of metals and alloysseem to follow the same, well established trends in structu re a ndproperties as bulk materials produced by more conventionalwrought techniques. The state of unders tanding of the mech-anical behavior of thick films of refractory co mpou nds is stillin its infancy and much work r emains to be done for this veryimportant class of materials.

A c k n o w l e d g e m e n t sThe support of the National Science Foundation under GrantDM R 75-13347 is grate fully acknowledged .

R e f e r e n c e s' L Holland, Vacuum Deposition of Thin Films, Chapman & Hall,London (1956).L Maissl and R H Clang (editors), Handbook o f Thin Film Tech-nology, McGraw-Hill, New York 0970).3 C A Neugebauer, J B Newkirk and D A Vermilyea (editors),Structure and Properties of Thin Films, Wiley, New York (1959).4 R W Hoffman and H G F Wilsdorf (editors), Thin Films, AmericanSociety for Metals (1964).s R Niedemeyer and H Mayer (editors), Basic Problems in Thin FilmPhysics, Vandenhceck and Ruppercht, Gottengen (1966).6 Physics o f Thin Films, Academic Press, New York 0963) (onwards---in multiple volumes).J A Allen, Re~' Pure Appl Chem, 4, 1954, 133.8 G A Bassctt and D W Pashley, J lnst Metals, 87, 1958, 449.'~ R W Hoffman, Thin Films, p 99, American Society for Metals(1964).Jo R W Hoffman, Physics of Thin Fihns, 3, 1966, 246, AcademicPress, New York., i W Buckel, J Vac Sci Technol, 6, 1969, 696.~2 K Kinosita, Thh~ Solid Films, 12, 1972, 17.~3 R F Bunshah, Proc 4th lnt Cant on Vacuum Metallurgy, p 17,Iron and Steel Inst Japan (1973).~4 R F Bunshah, J Vac Sci Technol, 11, 1974, 633.as R F Bunshah, J Vac Sci Technol, 11, 1974, 814.6 R F Bunshah, New Trends in Materials Processing, p 200, AmericanSociety for Metals (1976).~ B E Paton, B A Movchan and A V Demchishin, Proc 4th lnt Con.[on Vacuum Metallurgy, p 251, Iron and Steel lnst Japan (1973).~s D W Pashley, Adv Phys, 5, 1956, 173.~9 A Van der Drift, Phillips Res Rep, 22, 1967, 267.2o j A Thornton, Ann her Mater Sci, 1977, to be published.2~ B A Movchan and A V Demshishin, Fizika Metall, 28, 1969, 83.22 j A Thornton, J Vac Sci Technol, 11, 1974, 666.2~ j W Beams, J B Breazeale and W L Bart, Phys hey, 100, 1955, 1657.z,,j W Beams, Structure and Properties of Thin Films, p 183, Wiley,New York (1959).z5 A Catlin and W P Walker, JApplPhys , 31, 1960, 2135.26 S Jovanovic and C S Smith, J Appl Phys, 32, 1961, 121.2, p I Krukover and V A Buravikhin, Fizika Metall, 22, 1966, 144.~s D G Brandon and Z Bauer, israelJ Technol, g, 1970, 247.~9 D M Marsh, J Sci lnstrum, 38, 1961, 229.50 C A Neugebauer, J Appl Phys, 31, 1960, 1096.3a C D'Antonio, J Hirschorn and L Tarshis, Trans AIME , 227, 1964,1346.

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6 s H R S m i t h , K K e n n e d y a n d F J B o e r ic k e , J Vac Sci Technol, 7,1970, $48 .6 6 B A M o v c h a n , A V D e m i c h i s h i n a n d L V K o o l u c k , J Vac SciTechnol, 11, 1974 , 869 .6 7 H Y a m a m o t o a n d G K a m o s h i t a , Trans Japan lnst Metals, 1 2 ,1971, 12.6 , L S P a l a t n i k , M Y a F u k s , A 1 I I ' y in s k i y a n d O G A l a v e r d o v a ,Fizika Metali, 22, 1966, 744.6 9 C A O H e n n i n g , F W B o s w e l l a n d J M C o r b e t t , Acta Met, 23,1975, 177.7 0 K K Z i l i n g , L D P o k r o v s k i y a n d V Y u P o h e l k i n , Fizika Metall,29, 1970 , 1112 .7 t L S P a l a t n i k , A I I ' ly i n s k i y a n d A G R a v l i k , Fizika Metall, 19 ,1965, 310.72 G M a h a n d C W N o r d i n , Proc 16th Annual ConfSoc of VacuumCoaters, p 1 0 3 , C h i c a g o ( 1 9 7 3 ) .7 3 C A O H e n n i n g , F W B o s w e l l a n d J M C o r b e t t , Acta Met, 23,1975, 187.7 4 L S P a l a m i k , A I I I ' y in s k i y , A G R a v h k , A A N e c h i t a y l s a n dG Y e L y a k h , Flzika Metall, 27, 1969, 1114.7 s C D T u r k a n d H L M a r c u s , Trans Met Soc AIME, 232, 1968 , 2251 .~ 6 M A S h e r m a n , R F B u n s h a h a n d H A l k a l e , 1 2 , 19 7 5, 6 97 .7 7 F C F r a n k a n d B R L a w n , P r o c R S O c L o n d , 2 9 9 A , 1 9 6 7 , 2 9 1 .7 s M C o l e n a n d R F B u n s h e h , J Vac Sci Technol, 13, 1976 , 536 .~ 9 A C R a g h u r a m a n d R F B u n s h a h , J Vac Sci Technol, 9, 1972, 1389.8 0 G M a h , C W N o r d e n a n d J F F u l l e r , J Vac Sci Technol, 11, 1974,3 7 1 .8 , R F B u n s h a h a n d R J S c h r a m m , iThin Solid Films, 41, 1977, inpre s s ., 2 W G r o s s k l a u s a n d R F B u n s h a h , J Vac Sci Technol, 12, 1975 , 593 .s 3 S F u r u u c h i , H S a k a t a a n d K A i w a k a , Japan J Appi Phys, 13, 1974 ,1905.. 4 W G r o s s k l a u s a n d R F B u n s h a h , J Vac Sci Technol, 12, 1975, 811.. 5 K W a s a , T N a g a i a n d S H a y a k o w a , Thin Solid Films, 3 1 , 1 9 7 6 ,2 3 5 .. s C A O H e n n i n g , F W B o s w e l l a n d J M C o r b e t t , Acta Met, 23,1975, 193., 7 L S P a l a t n i k , A I l ' l y n s k i y a n d N P S a p e l k i n , Soviet Phys Solid St,8, 1967 , 2016 .. s I I S o l o n o v i c h a n d V I S t a r t s e v , Problemy Prochn. 1, 1973 , 28 .s 9 L S P a l a t n i k , A I l 'l y i n s k i y , N M B i l e t c h a n k o a n d R I S i n e l - n i k o v a ,Fizika Metall, 32, 1971 , 199 .9 0 R F B u n s h a h , Y D G u p t a a n d A C R a s h u r a m , u n p u b l i s h e d d a t a .9 t V S P o s tn i k o v , I V Z o l o t h u k h i n a n d V K B e l o n s o v , Fizika Metall,26, 1968 , 957 .9 z A C R a l l h u r a m , R N i m m a s a d d a , R F B u n s h a h a n d C N J W a s h e r ,Thin Solid Films, 20, 1974, 187.9 3 R F ' B u n s h a h a n d A C R a g h u r a m , J Vac Sci Technol, 9, 1972, 1385.

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bunshah - mechanical properties of thin films

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