SIMS AND SCANNING ION MICROSCOPY

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SIMS AND SCANNING ION MICROSCOPY

G. Allen, I. Brown

To cite this version:

G. Allen, I. Brown. SIMS AND SCANNING ION MICROSCOPY. Journal de Physique Colloques,

1989, 50 (C2), pp.C2-121-C2-125. �10.1051/jphyscol:1989221�. �jpa-00229419�

SIMS AND SCANNING ION MICROSCOPY

G.C. ALLEN and I.T. BROWN

Central Electricity Generating Board, Berkeley Nuclear Laboratories, Berkeley, GB-Gloucestershire GL13 9PB, Great-Britain

Resume

-

Un m i c r o s c o p e

a

b a l l a y a g e i o n i q u e d e v e l o p p e aux " B e r k e l e y

- -

N u c l e a r L a b o r a t o r i e s " du C . E . G . B . , e s t d e c r i t .

P a r bombardement i o n i a u e a p a r t i r d ' u n e s o u r c e de g a l l i u m m e t a l 1 i q u i d e e t a n a l y s e s c o n s e c u t i v e s d e s i o n s s e c o n d a i r e s e t d e s

e l e c t r o n s emi s , s e l on d e s t e c h n i q u e s c o n v e n t i o n n e l l e de s p e c t r o s c o p i e de masse e t de m i c r o s c o p i e e l e c t r o n i q u e , c e t a p p a r e i l p e r m e t

d ' o b t e n i r l e s p e c t r e de masse d e s i o n s s e c o n d a i r e s e t de v i s u a l i s e r 1 a s u r f a c e exami nee.

Des r e s u l t a t s de m i c r o s c o p i e

a

b a l l a y a g e a p p l i q u e e s a d e s e t u d e s de m a t e r i a u x m e t a l l i q u e s , i n o r q a n i q u e s e t o r g a n i q u e s e r o n t p r e s e n t e s .

A b s t r a c t

-

A s c a n n i n g i o n m i c r o s c o p e d e v e l o p e d a t t h e C E G B ' s B e r k e l e y N u c l e a r L a b o r a t o r i e s i s d e s c r i b e d .

By i o n bombardment from a l i q u i d metal g a l l i u m s o u r c e , a n d s u b s e q u e n t a n a l y s i s of both t h e r e s u l t a n t s e c o n d a r y i o n s and s e c o n d a r y e l e c t r o n s u s i n g c o n v e n t i o n a l t e c h n i q u e s of mass

s p e c t r o m e t r y and e l e c t r o n m i c r o s c o p y , t h i s i n s t r u m e n t o f f e r s b o t h s e c o n d a r y i o n mass a n a l y s i s (SIMS) and t h e f a c i l i t y f o r i m a g i n g t h e s u r f a c e u n d e r i n v e s t i g a t i o n .

R e s u l t s from t h e a p p l i c a t i o n of t h e s c a n n i n g i o n m i c r o s c o p e t o t h e s t u d y of m e t a l 1 i c y i n o r q a n i c and o r q a n i c m a t e r i a l s a r e p r e s e n t e d .

The t e c h n i q u e s used f o r t h e e x a m i n a t i o n and a n a l y s i s of s o l i d s a r e many and v a r i e d b u t t h e i r d e v e l o p m e n t may be t r a c e d u s i n q 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 a s a s t a r t i n g p o i n t . F o l l o w i n g t h e i n t r o d u c t i o n of t h i s method came t h e d e s i r e t o d e t e r m i n e t h e c h e m i c a l c o m p o s i t i o n of t h e f e a t u r e s r e v e a l e d . A t f i r s t t h i s was p o s s i b l e t h r o u g h t h e a n a l y s i s o f X - r a d i a t i o n p r o d u c e d d u r i n g t h e p r o c e s s of bombardment of t h e specimen w i t h t h e h i g h e n e r g y e l e c t r o n beam, b u t two d e c a d e s ago t e c h n i q u e s o f f e r i n g i n f o r m a t i o n more r e p r e s e n t a t i v e of t h e s u r f a c e s u c h a s 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 , Auger e l e c t r o n s p e c t r o s c o p y (AES) and s e c o n d a r y i o n mass s p e c t r o m e t r y (SIMS)

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1989221

C2-122 JOURNAL DE PHYSIQUE

w e r e d e v e l o p e d . Of t h e s e methods a c c e p t a n c e was g a i n e d most s l o w l y by t h e l a t t e r b u t m i c r o s c o p i c a n a l y s i s by SIMS h a s been made p o s s i b l e by t h e u s e o f l i q u i d m e t a l s o u r c e s t o p r o d u c e t h e p r i m a r y i o n beaml. T h e s e h i q h

b r i g h t n e s s s o u r c e s p e r m i t t h e f o r m a t i o n of h i g h i n t e n s i t y s u b m i c r o n i o n p r o b e s and modern i n s t r u m e n t a t i o n a l l o w s t h e c o l l e c t i o n of s e c o n d a r y e l e c t r o n and s e c o n d a r y i o n i m a g e s which p r o v i d e s u r f a c e t o p o g r a p h y of o n e m o n o l a y e r 2 . The B e r k e l e y i n s t r u m e n t , shown s c h e m a t i c a l l y i n F i g u r e 1 , i s t h e r e f o r e , a c o m b i n a t i o n of a m i c r o s c o p e and a s u b m i c r o n a n a l y t i c a l p r o b e ^{3 .}

DETECTOR r

- - -

*

MASS LIQUID METAL

I O N GUN

VACUUM SYSTEM

2 5

^DISPLAY D l SPLAY

COPIER / PRINTER

i--i

F i g u r e 1: S c h e m a t i c d i a g r a m of B e r k e l e y S c a n n i n g I o n M i c r o s c o p e (SIM) T y p i c a l images from a number of s p e c i m e n s d i f f i c u l t t o e x a m i n e w i t h o u t p r i o r c o a t i n g t e c h n i q u e s which mask o r modify i m p o r t a n t s u r f a c e c h e m i c a l p r o p e r t i e s i n c o n v e n t i o n a l e l e c t r o n m i c r o s c o p y a r e shown i n F i g u r e s 2 and 3 .

F i g u r e 2 : Ion i n d u c e d e l e c t r o n m i c r o g r a p h from f o o t of h o r s e f l y ( T a b a n u s )

p a r t i c l e ( b ) a r e a of p a r t i c l e a t h i g h e r m a g n i f i c a t i o n O r g a n i c m a t e r i a l s a r e n o r m a l l y d e g r a d e d i n an e l e c t r o n beam and i n s u l a t i n g s a m p l e s such a s t h e PFA sample ( F i g u r e 3 ) which i s m a i n l y composed of s i l i c a , may be s u b j e c t t o c h a r g i n g

'+.

I n t h e i o n m i c r o s c o p e however, good images w i t h a r e m a r k a b l e d e p t h of f i e l d w e r e o b t a i n e d a f t e r s e v e r a l m i n u t e s ; p r e s u m a b l y t h e i m p l a n t a t i o n of gal 1 ium i o n s a1 l e v i a t e s t h e b u i l d up of s u r f a c e c h a r g e d u r i n g t h e bombardment p r o c e s s .

Bombardment of t h e s u r f a c e w i t h i-ons n o t o n l y p r o d u c e s s e c o n d a r y e l e c t r o n s b u t a l s o s t i m u l a t e s t h e e m i s s i o n of s e c o n d a r y i o n s . I f t h e p r i m a r y i o n beam i s r a s t e r s c a n n e d o v e r t h e s u r f a c e and s p e c i f i c s e c o n d a r y i o n s m o n i t o r e d a t each p o i n t , a c h e m i c a l image can be g e n e r a t e d : T h i s i s done by computer p r o c e s s i n q t h e d a t a t o y i e l d maps o r s p a t i a l images of t h e s e c o n d a r y i o n s a n a l y s e d which may t h e n be r e l a t e d t o e l e c t r o n i m a g e s from t h e same s u r f a c e ( F i g u r e 4 ) .

( a ) ( b )

F i g u r e 4 : ( a ) Ion i n d u c e d e l e c t r o n image of w e a r s c a r s on t h e s u r f a c e of a s t a i n 1 e s s s t e e l sampl e .

( b ) Map of t h e O H - i o n t a k e n from t h e same sample.

C2-124 JOURNAL DE PHYSIQUE

To d e m o n s t r a t e t h e u s e of t h e i n s t r u m e n t i n s e c o n d a r y i o n mass a n a l y s i s (SIMS) t h s u p e r c o n d u c t i n g compound YBa2Cu307-x h a s been examined 5 . The p o s i t i v e i o n s p e c t r u m from a f r e s h l y p r e p a r e d s a m p l e i s shown i n F i g u r e 5 ( a ) and may be compared w i t h t h a t from t h e same m a t e r i a l f o l l o w i n g l e n g t h y e x p o s u r e t o t h e a t m o s p h e r e F i g u r e 5 ( b ) . The p r e s e n c e of a h y d r o x i d e l a y e r a t t h e s u r f a c e of t h e sample e x p o s e d t o a i r i s r e a d i l y a p p a r e n t . Although t h i s l a y e r i s r e a d i l y removed by s p u t t e r i n g t h e p r e s e n c e of y t t r i u m and barium h y d r o x i d e s c o u l d p l a y a s - i g n i f i c a n t r o l e i n s u r f a c e c o n d u c t i o n b e h a v i o u r .

F i g u r e 5: P o s i t i v e SIMS S p e c t r a f o r YBa2Cu307-x ( a ) F r e s h l y S i n t e r e d ( b ) Exposed t o t h e Atmosphere

The i n t e n s i t i e s of t h e v a r i o u s c l u s t e r i o n s i n t h e s p e c t r a a r e n o t r e l a t e d t o t h e c o m p o s i t i o n of t h e s a m p l e . They a r e a r e s u l t of t h e

t h e r m o d y n a m i c / c h e m i c a l e q u i 1 i b r i a i n v o l v e d i n t h e s p u t t e r i n g p r o c e s s 5 . The bond d i s s o c i a t i o n e n e r g i e s f o r m e t a l o x i d e i o n s a r e p l o t t e d a g a i n s t t h e f u n c t i o n l o g ( M O + / M + ) i n F i g u r e 6 . T h i s r e l a t i o n s h i p s u g g e s t s t h a t a s t h e d i s s o c i a t i o n e n e r g y of t h e m e t a l o x i d e d e c r e a s e s , t h e o b s e r v e d m e t a l - o x i de peak becomes l e s s p r o m i n e n t .

F i g u r e 6: R e l a t i o n s h i p b e t w e e n m e t a l o x i d e SIMS i n t e n s i t i e s a.nd s t a b i l i t y o f m e t a l o x i d e i o n .

ACKNOWLEDGEMENT

The w o r k was c a r r i e d o u t a t t h e B e r k e l e y N u c l e a r L a b o r a t o r i e s o f t h e R e s e a r c h D i v i s i o n a n d t h e p a p e r i s p u b l i s h e d w i t h t h e p e r m i s s i o n o f t h e C e n t r a l E l e c t r i c i t y G e n e r a t i n g B o a r d .

REFERENCES

1 P.D. P r e w e t t , D.K. J e f f r i e s . I n s t . P h y s . C o n f . S e r . V o l . 5 4 . L i q u i d m e t a l f i e l d e m i s s i o n i o n s o u r c e s a n d t h e i r a p p l i c a t i o n s . I n s t i t u t e o f P h y s i c s , B r i s t o l ( 1 9 8 0 ) p 3 1 6 .

2 R. L e v i - S e t t i , J.M. B h a b a l a , Y.L. Wang. U l t r a m i c r o s c o p y ( 1 9 8 8 1 ,

24,

9 7 G.C. A l l e n , I . T . Brown. CEGB R e s e a r c h ( 1 9 8 8 ) i n p r e s s .

4 G.C. A l l e n , A.R. J o n e s , A.G. W a r n e r . P a r t . C h a r a c t . ( 1 9 8 6 1 ,

3,

8 9 . 5 G.C. A l l e n , I . T . Brown. P h i l . Mag. L e t t e r s ( 1 9 8 8 ) i n p r e s s .