MIXAGE PAR FAISCEAU LASER PULSE DE MULTICOUCHES DE FER ET D'ALUMINIUM DEPOSE SOUS VIDE

(1)

HAL Id: jpa-00223159

https://hal.archives-ouvertes.fr/jpa-00223159

Submitted on 1 Jan 1983

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

MIXAGE PAR FAISCEAU LASER PULSE DE MULTICOUCHES DE FER ET D’ALUMINIUM

DEPOSE SOUS VIDE

E. Mathe, C. Jaouen, A. Bellara, J. Muller

To cite this version:

E. Mathe, C. Jaouen, A. Bellara, J. Muller. MIXAGE PAR FAISCEAU LASER PULSE DE MUL-

TICOUCHES DE FER ET D’ALUMINIUM DEPOSE SOUS VIDE. Journal de Physique Colloques,

1983, 44 (C5), pp.C5-507-C5-511. �10.1051/jphyscol:1983574�. �jpa-00223159�

(2)

MIXAGE PAR FAISCEAU LASER PULSE DE MULTICOUCHES DE FER E T D'ALUMINIUM DEPOSE SOUS V I D E

E.L. Mathe, C. Jaouen, A. B e l l a r a e t J.C. ~ u l l e r *

Laboratoire de Me'taZZurgie Physique, FacuZte' des Sciences,

4 0

avenue du Recteur Pineau,

86022

P o i t i e r s Cedex, France

* ~ a b o r a t o i r e PHASE, Centre de Recherches Nuciie'aires,

2 3

rue du Loess,

67037

Strasbourg Cedex, France

Ri5sumQ-

-

L'Qtude d e s phases obtenues a p r s s mixage de multicouches Al-Fe p a r i r r a d i a t i o n l a s e r p u l s s e t par i m p l a n t a t i o n b temp6ra- t u r e ambiante montre que dans c e r t a i n e s c o n d i t i o n s c e s deux t r a i - tements conduisent aux mZmesstructures r e c r i s t a l l i s Q e s .

A b s t r a c t

-

Study of t h e phases obtained a f t e r mixing of m u l t i - l a y e r s of Fe-A1 by l a s e r p u l s e or i o n i m p l a n t a t i o n show t h a t , w i t h c e r t a i n c o n d i t i o n s , t h e s e two t r e a t m e n t s give t h e same r e c r y s t a l - l i s a t i o n s t r u c t u r e s .

I

-

INTRODUCTION

S e v e r a l methods a r e a c t u a l l y s t u d i e d t o r e a l i s e on t h e s u r f a c e of m e t a l l i c or semi- conductor s u b s t r a t e s , a l l o y l a y e r s of mechanical o r e l e c t r i c a l i n t e r e s t between t h e s e , i o n i m p l a n t a t i o n which g i v e s l a y e r s deeper than t e n t h of nanometers b u t of l i m i t e d c o n c e n t r a t i o n because of " s p u t t e r i n g t ' phenomenon / 1 , 2 /

.

Another p o s s i b i l i t y which a v o i d s t h i s l a s t problem c o n s i s t s i n mixing, on t h e s u b s t r a c t , s u c c e s s i v e l a y e r s of deposited elements by i m p l a n t a t i o n of an a u x i l i a r y i o n a s Ar++ o r ~ e + + b u t t h e d e p t h of t h e a l l o y e d l a y e r i s l i m i t e d by i o n p e n e t r a t i o n .

By mixing by pulsed l a s e r i r r a d i a t i o n t h e same kind of m u l t i l a y e r s , i t i s hoped t o r e a c h 3,5)im d e p t h but t h e s u p e r f i c i a l v a p o r i s a t i o n has t o be taken i n c o n s i d e r a t i o n when high f l u e n c e s a r e used / 3 1.

Many previous s t u d i e s of i r r a d i a t i o n s of m u l t i l a y e r s Si-metal have been a l r e a d y done.In c a s e of pulsed l a s e r , t h e l i q u i d f i l m which forms on t h e s u r f a c e o f t e n c r y s t a l l i s e s i n columns of S i between a mixture of s i l i c i d e s / 4 , 5 /. Xe i m p l a n t a t i o n or Laser i r r a d i a t i o n of d i f f e r e n t systems a s AuGe AlGe AuSi AgSi have been compared by VONALLMEN e t a l . / 6 , 7 / : t h e a b i l i t y t o mixing seems t o be c o r r e l a t e d t o t h e e x i s t e n c e o r n o t of m e t a s t a b l e phase a t low temperature. Some r e s u l t s on metal-metal m u l t i l a y e r s mixing by i m p l a n t a t i o n have been published /8,7/ and by r e s i s t i v i t y measurements Delafond and RiviCre a r e showing t h e i n f l u e n c e of dose temperature and ion n a t u r e on t h e mixing k i n e t i c ( t o be published) but i t has n o t been done comparison between l a s e r mixing and i m p l a n t a t i o n mixing an t h e same m u l t i l a y e r s . Our purpose i s t o compare t h e s t r u c t u r e s o b t a i n e d by Ruby l a s e r i r r a d i a t i o n and by Xenon i m p l a n t a t i o n i n I r o n and Aluminum, vacuum d e p o s i t e d on d i f f e r e n t s u b s t r a c t s . I1

-

EXPERIMENTAL

The s u b s t r a t e s used a r e jlst clived ClNa, g l a s s , or annealed and polished p o l y c r i s t a l - l i n e A 1 99,99". The m u l t i l a y e r s a r e obtained by 6 s u c c e s s i v e e v a p o r a t i o n s of a l t e r - n a t i v e l y I r o n and Alumi um, t h e l a s t b e i n g Aluminum. They were performed i n a high vacuum d e v i c e ( p

<

^lo-' Torr) by J o u l e e f f e c t . The t o t a l t h i c k n e s s o f the l a y e r i s about 1000A, t h e t h i c k n e s s of every l a y e r being c a l c u l a t e d t o o b t a i n an average c o n c e n t r a t i o n of 40 % atomic of Aluminum. These t h i c k n e s s e s a r e c o n t r o l l e d d u r i n g e v a p o r a t i o n by a q u a r t z d e t e c t o r .

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1983574

(3)

C5-508 JOURNAL DE PHYSIQUE

For l a s e r i r r a d i a t i o n s , t h e m u l t i l a y e r s remain on t h e s u b s t r a t e k e p t a t room tem- p e r a t u r e . The l a s e r (of PHASE group i n Strasbourg) o p e r a t e s with 20 n s impulsions, a beam diameter of 8 mm and energy d e n s i t i e s between 1 and 1,5 J o u l e s x cm-2. Only one p u l s e i s done every time.

A f t e r i r r a d i a t i o n , t h e samples, wether a r e taked o f f t h e s u b s t r a t e by d i s s o l u t i o n i n c a s e of ClNa o r g l a s s o r , i n c a s e of A 1 s u b s t r a t e a r e c u t i n small s q u a r e s and j e t e l e c t r o t h i n n e d by t h e r e a r f a c e .

Ion i m p l a n t a t i o n of ~ e + a r e performed a t room temperature a f t e r d i s s o l u t i o n of t h e ClNa s u b s t r a t e and d e p o s i t i o n on a g r i d . The implanted dose was 1016 i o n s x cm-2 and t h e a c c e l e r a t i o n v o l t a g e 360 keV.

The o b s e r v a t i o n s a r e done i n a JEOL 200 CX e l e c t r o n microscope o p e r a t i n g a t 200 keV 111

-

EXPERIMENTAL RESULTS

a ) To understand t h e obtained r e s u l t s , i t i s n e c e s s a r y t o keep i n mind some f e a t u r e s r e l a t i v e t o t h e FeAl a l l o y .

A t t h e o e q u i l i b r i u m s t a t e , t h e Fe-A1 40 % a t . i s BC and i t s l a t t i c e parameter i s 2,897 A. It i s an ordered a l l o y B2 type and g i v e s on d i f f r a c t i o n diagram e x t r a s p o t s f o r ( h k l ) p l a n e s w i t h h+k+l = 2n+l. This o r d e r s t a t e i s very s t a b l e : i t i s n o t destroyed even by quench from t h e m e l t by s p l a t c o o l i n g / 9 / o r i m p l a n t a t i o n

/ l o / . But i n t h e s e two c a s e s a new c o n f i g u r a t i o n may be observed j u s t a f t e r s p l a t c o o l i n g o r d u r i n g r e c r y s t a l l i s a t i o n a f t e r i m p l a n t a t i o n /11,10/ : Needles of a FCC compound whose l a t t i c e parameter i s a = 3.75 appear. This new phase p r e s e n t s an ordered s t r u c t u r e L l o w h i c h corresponds a t t h e accumulation of t h e same s o r t of atom on one of t h e <001> d i r e c t i o n s . W e a r e going t o compare now wieh t h e r e s u l t s obtained on t h e m u l t i l a y e r s .

b) J u s t a f t e r e v a p o r a t i o n f i g . 1 t h e m u l t i l a y e r i s composed of small g r a i n of A 1 and Fe completely d e s o r i e n t e d and t h e d i f f r a c t i o n diagram shows q u a s i continuous r i n g s ( F i g . I ) .

: h k l : A 1 : Fe : Fe-A1: L10 :

.______._--___._---.---.---.

I f t h e mixing t a k e s p l a c e t h e most : 001 : : 2.89 : 3.75 :

v i s i b l e f e a t u r e w i l l be t h e d i s p a r i t i o n : 1 1 0 : : 2.02 :

2.05:

2.75 : of t h e < I l l > A 1 r i n g and t h e t r a n s f o r - : 1 1 1 : 2.33 : : 1.67

:=

^:

mation of t h e <112> Fe and <311>, <222> : 200 : 2.02 : 1.43 :

1.45: 1.87

: A1 r i n g s i n t o one s i n g l e <112> r i n g of : 201 : : 1.29 : 1.68 : Fe-A1 a s shown i n t h e r i g h t t a b l e . : 1 1 2 : : 1.16 :

1.18

: 1.53 : : 220 : 1.43 : 1.01 : 1.02 : 1.32 :

: 2.21 : 0.96 1.250

:

: 300 :

: 310 : : 0.50 :

0.92

: 1.185 :

: 311 : 1.22 : : 0.87 :

1.13

^:

: 2 2 2 t . 1 . 1 7 : 0.825 :

0.83: 1.08

:

c) Laser mixing

The t r a n s f o r m a t i o n of t h i s "sandwich" w i l l d e ~ e n d on t h e s u b s t r a t e and i t s h e a t c o n d u c t i v i t y and c r i s t a l l i n i t y , and on t h e l a s e r f l u x . The r o l e of t h e temperature of t h e s u b s t r a c t which i s very important i s n o t r e l a t e d h e r e . To summarize a l l t h e experimental r e s u l t s , we s h a l l compare t h e s t r u c t u r e s obtained w i t h t h e same energy d e n s i t y l , & ~ z m - ~ o n t h e t h r e e types of s u b s t r a t e and on t h e most i n t e r e s t i n g of them two f luences

.

Deposition on g l a s s

The l a y e r becomes t r a n s p a r e n t i n t h e beam s h o t because of important v a p o r i s a t i o n with t h e 1,45 ~ / c m 2 f l a s h . The a s p e c t of t h e l a y e r and d i f f r a c t i o n diagram a r e

(4)

e x t r a r i n g s a r e observed : The mixing seems t o be n o t complete b u t c o n d u c t s t o a d i s o r d e r e d a l l o y w i t h v e r y s m a l l d e s o r i e n t e d a r a i n s .

-

D e p o s i t i o n on NaCl

For t h e same f l u x t h e g r a i n s a r e l a r g e t h a n on g l a s s and t h e d i f f r a c t i o n r i n g s a r e n o t s o c o n t i n u o u s (Fig.3).The A1 r i n a i s n o t v i s i b l e b u t i t remains a d i f f u s e d i f f r a c t i o n b u t n o o r d e r e d r i n g s o r s p o t s a r e observed : The mixing i s more c o m ~ l e t e t h a n on a l a s s and c o n d u c t s a l s o t o d e s o r d e r e d FeA1.

-

D e p o s i t i o n on Aluminium

A 1 , 2 J.cm-2 i r r a d i a t i o n g i v e s r i s e t o f o r m a t i o n of s m a l l g r a i n s o f d i f f e r e n t s t r u c t u r e s and o r i e n t a t i o n s : on t h e d i f f r a c t i o n d i a g r a m t h e y a p p e a r s a s s p o t s on r i n g s (Fig.4) c o r r e s p o n d i n g t o o r d e r e d B.C. FeAl and t o Li p h a s e . A i n c r e a s i n g of t h e e n e r g y d e n s i t y t o 1 , 4 ~ . c m - ~ i n d u c e s t h e f o r m a t i o n

09

w e l l d i s t i n c t g r a i n s of g e n e r a l l y d e s o r d e r e d Fe-A1 and L I 0 phase and t h e d i f f r a c t i o n d i a g r a m i s o n l y a s p o t diagram. I n some p l a c e s e x t r a s p o t s rlOO>FeAl a p p e a r

.

Some A1 s p o t s showing t h a t t h e f l u e n c e i s h i g h enough t o m e l t a l a y e r of t h e s u b s t r a t e a r e a l s o o b s e r - v a b l e ( F i g . 5 )

d) Ion i m p l a n t a t i o n mixing

J u s t a f t e r i m p l a n t a t i o n t h e l a y e r i s e n t i r e l y mixed and formed of s m a l l v e r y w e l l d e s o r i e n t e d g r a i n s o f d i s o r d e r e d a l l o y FeAl ( P i g . 5 ) . I n some p l a c e s a f a i n t l i g h t i s observed a t t h e

<loo>

r i n g p l a c e .

A f t e r i n s i t u a n n e a l i n g i n t h e microscope by s t e p s of 50°C no m o d i f i c a t i o n o f t h e diagram o c c u r s b e f o r e 50O0C;at 550°C g r a i n s become l a r g e and on t h e d i a g r a m appear s p o t s on r i n g s whose d i a m e t e r s a r e t h o s e o f L10 p h a s e . But i n t h i s c a s e , t h e a s p e c t of t h e g r a i n s a r e v e r y d i f f e r e n t of t h a t i s o b s e r v e d a f t e r i m p l a n t a t i o n of t h e b u l k m a t e r i a l i n which L10 h a s a n e e d l e form ( F i g . 6 ) . Another f e a t u r e t o n o w i s t h a t no o r d e r t a k e s p l a c e a t t h i s t e m p e r a t u r e .

I V

-

DISCUSSION CONCLUSION

The r e s u l t s o b t a i n e d by l a s e r mixing w i t h t h e same e n e r g y d e n s i t y and d i f f e r e n t subs- t r a c t show t h a t when t h e s u b s t r a c t h a s a bad t n e r m a l conductivity (NaCl o r g l a s s ) t h e d e p o s i t e d e n e r g y i s c o n c e n t r a t e d i n t o t h e l a y e r and t h e v a p o r i s a t i o n i s more impor-

t a n t . I n a l l c a s e s t h e quenching r a t e i s s u f f i c i e n t l y h i g h t o quench t h e d i s o r d e r e d s t a t e o f t h e a l l o y t h a t was i m p o s s i b l e by s p l a t c o o l i n g b u t when some e n e r g y i s d r a i n e d i n t h e A1 s u b s t r a c t a n o t h e r s t e p of t h e t r a n s f o r m a t i o n between l i q u i d and B.C. o r d e r e d FeAl i s k e p t t h a t c o r r e s p o n d s t o L I 0 a p p a r i t i o n . The p r e s e n c e o f t h i s p h a s e i m p l i e s t h a t a p r e v i o u s s t a t e of t h e s y s t e m i s a FCC d e s o r d e r e d p h a s e which by d i s p l a c i v e t r a n s f o r m a t i o n a t s o l i d s t a t e g i v e s L I O o r d e r e d phase / 111

.

A f t e r

s p l a t c o o l i n g , i t was n o t observed s i m u l t a n e o u s l y disordered BC a l l o y and o r d e r e d L10 phase : t h e a l l o y i s supposed t o o r d e r more q u i c k l y t h a n t h e L I 0 s t r u c t u r e . I n c a s e of l a s e r i r r a d i a t i o n , t h e g r a i n form w i t h o u t w e l l c r i s t a l l o g r a p h i c a l l y d e f i n e d b o u n d a r i e s , s u g g e s t s t h a t t h e mechanism o f growth o f t h e g r a i n a f t e r nu- c l e a t i o n i s q u i t e d i f f e r e n t of i n c a s e of s p l a t c o o l i n g p r o c e s s . We have t o n o t e

(5)

C5-510 JOURNAL DE PHYSIQUE

Fig.1

-

Substrate : glass. After Fig.2

-

^Substrate^:NaC1. After laser laser irradiation. 1,4J x cm-2 irradiation 1,4J.cm-2

Fig.3

-

Substra tepoly-Al. After laser irradiation. 1,2J x

.g.4

-

Substratepdy.Al. After laser .radiation 1,4 J x ~ m - ~ .

Fig.5

-

After implantation of xet'+ Fig.6

-

After implantation and in situ at room temperature (dose : annealing until 550°c during 40 minutes.

16 -2

10 ions x cm

(6)

observed phases even when the substrate is supposed to melt (1,4 J x cm-') and only modify the crystallites size.

The Xe implantation at room temperature conducts to an homogeneous disordered Fe-A1 alloy and without any modification of the surface aspect. By further annealing, recrystallisation takes place and finally the obtained structure seems to be the same as after laser irradiation on A1 substrate. The nature of the phases are also the same than after implantation of the bulk material but, as in the case of laser irradiation, the aspect of the L10 phase and then its growth are not similar.

In conclusion we find here the already known similarity between ion implantation, pulsed laser treatment and splat cooling /12,13/

.

When the quenching rate is high enough it is possible to obtain disordered Fe-A1 alloy. The advantage of laser treatment is its rapidity but it conducts to a phase mixture while implantation gives only the solid solution. By a further annealing of implanted sample the obtained structures are in this case very similar.

REFERENCES

1. TSAUR B.Y., LIAU Z.L., MAYER J.W., Appl. Phys. Lett.

34,

(1979), 168.

2. TSAUR B.Y., LAU S.S., LIAU Z.L., MAYER J.W. Appl. Phys. Lett.

6,

(1980), 823.

3. AMMESH K.J., KULKARNI N., SOOD D.K., SUNDARARAMAN H., YADAV R.D.S., Proc.

4 th International Conf. on Ion Beam analysis Aarhus (1979) and Nucl. Inst.

Methods 168, (1980), 275.

4. POATE J.M.,LEAMY H.J., SHANG T.T., CELLAR G.K., Appl. Phys. Lett.

2,

(1978) 918.

5. WITTMER M. VON ALLMEN M., J. Appl. Phys. 50, (1979), 4786.

6. VON ALLMEN M., LAU S. S

. ,

P&ENP& M., TSAUFB.Y., Appl

.

^Phys

.

^Lett.

^2,

⁽¹⁹⁸⁰⁾

205.

7. LAU S.S., TSAUR B.Y., VON ALLMEN M., MAYER J.W., STRIKZKER B., WHITE C.W., APLLETON B., Ion Beam Modification in Materials Conference Proceedings, Albany (1981), 97.

8. TSAUR B.Y., HUNG L.S., MAYER J.N. ref.7, 67.

9. JUNQUA N., Thesis Poitiers, France (1981).

10. RIVIERE J.P., RUAULT M.O., SHACK M., CHAUMONT J., Radiation Effects to be published.

1 1 . JUNQUA N., GRILHE J., Scripta Met. Avril (1983).

12. SOOD D.K., Rad. Eff.

63

(1982), 141.

13. POATE J . M , BORDERS J.A., CULLIS A.G., HIRVONEN J.K., Appl. Phys. Lett.

30

(1977), 365.