CHARACTERIZATION OF DISLOCATIONS AND THEIR EFFECTS IN SILICON DEVICE TECHNOLOGY

(1)

HAL Id: jpa-00223071

https://hal.archives-ouvertes.fr/jpa-00223071

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.

CHARACTERIZATION OF DISLOCATIONS AND THEIR EFFECTS IN SILICON DEVICE

TECHNOLOGY

M. Kittler, W. Seifert, E. Bugiel, H. Richter

To cite this version:

M. Kittler, W. Seifert, E. Bugiel, H. Richter. CHARACTERIZATION OF DISLOCATIONS AND THEIR EFFECTS IN SILICON DEVICE TECHNOLOGY. Journal de Physique Colloques, 1983, 44 (C4), pp.C4-437-C4-443. �10.1051/jphyscol:1983451�. �jpa-00223071�

(2)

der DDR, DDR- 1156 Ber Zin-Rahnsdorf, Seestrasse 82, D.R. G.

REsum6 - On p r e s e n t e d e s e t u d e s m e t h o d i q u e s d e s c a u s e s d u c o n t r a s t E B f F a e s d i s l o c a t i o n s e t d e s o n e v a l u a t i o n . On m o n t r e d e s a p p l i - c a t i o n s d e l a methode E B I C 3 l a r e c h e r c h e d e l ' i n f l u e n c e d e s d i s l o c a t i o n s s u r l e s p e r f o m a n c e s d e c o m p o s a n t s , i n f l u e n c e n e g a - t i v e ( a u g m e n t a t i o n du c o n s t a n t i n v e r s e ) e t p o s i t i v e ( p i 6 g e a g e i n t e r n e ) .

A b s t r a c t

-

M e t h o d i c a l s t u d i e s on cause and v a l u a t i o n o f t h e d i s l o c a t i o n EBIC c o n t r a s t a r e presented. The a p p l i c a t i o n o f t h e EBIC method t o i n v e s t i g a t i o n s o f n e g a t i v e (enhanced

reverse c u r r e n t ) and p o s i t i v e ( i n t r i n s i c get t e r i n g ) e f f e c t s o f d i s l o c a t i o n s on device performance a r e demonstrated.

1. I n t r o d u c t i o n

-

^{W i}

d e f e c t i n f l u e n c e s on t h a t even i n d i v i d u a l

t h proceeding r e d u c t i o n o f device dimensions d e v i c e o p e r a t i o n g a i n growing importance so d i s l o c a t i o n s may become a s e r i o u s problem. On t h e o t h e r hand, p o s i t i v e e f f e c t s may r e s u l t from d i s l o c a t i o n s due t o g e t t e r i n g o f i m p u r i t i e s . Therefore, t h e r e a r i s e s t h e need f o r c h a r a c t e r i z a t i o n o f i n d i v i d u a l d i s l o c a t i o n s w i t h respect t o e l e c t r i c a l a c t i v i t y and g e t t e r i n g .

2. EBIC defect c o n t r a s t

-

^{I t}has been e s t a b l i s h e d t h a t t h e EBIC c o n t r a s t o f d i s l o c a t i o n s ( d e f e c t s ) depends i n a complex way on a l o t o f parameters: p r o p e r t i e s o f t h e defect (shape and p o s i t i o n , e l e c t r i c a l p r o p e r t i e s ) , p r o p e r t i e s o f t h e sample (doping and

d i f f u s i o n l e n g t h , measuring geometry), o p e r a t i n g c o n d i t i o n s o f t h e SEM /I,2,3/. The p r i m a r y i n t e r e s t o f EBIC d e f e c t i n v e s t i g a t i o n s i s t o o b t a i n i n f o r m a t i o n on e l e c t r i c a l defect p r o p e r t i e s which can n o t be r e a l i z e d by s i m p l e imaging o n 1

.

Even t h e v a l u e o f t h e EBIC c o n t r a s t c i s no d i r e c t measure f o r e x e c t r i c a l d e f e c t p r o e r t L e s

1

because t h e r e h o l d s a r e l a t i o n c = r x F ( R , L, geometry) etween s t r e n g t h

r

d e s c r i b i n g p r i m a r i l y t h e recombinat i o n p r o p e r t i e s o f t h e d e f e c t and c o n t r a s t c. The c o r r e c t i o n f a c t o r F i s a f u n c t i o n which takes i n t o accouat t h e i n f l u e n c e o f e l e c t r o n range R, o f d i f f u s i o n l e n g t h L o u t s i d e t h e d e f e c t , and o f geometry on c o n t r a s t /4/. For s e m i q u a n t i t a t i v e i n v e s t i g a t i o n s o f d e f e c t s t r e n g t h t h e c a l c u l a t i o n o f c o r r e c t i o n f a c t o r s on t h e base o f DONOLATO'S t h e o r y /5/ i s u s e f u l . An i m p o r t a n t r e s u l t o f h i s t h e o r y i s t h e p r e d i c t i o n o f a v e r y s m a l l dependence o f c o n t r a s t w i d t h on d i f f u s i o n l e n g t h . Fig. 1 shows a comparison between a s i m u l a t e d image o f a d i s l o c a t i o n

i n c l i n e d t o t h e s u r f a c e ( t a k e n from / 6 / ) and an e x p e r i m e n t a l

micrograph o f a corresponding d i s l o c a t i o n . I n b o t h cases t h e c o n t r a s t w i d t h i s i n t h e o r d e r o f t h e e l e c t r o n range R and n o t i n t h e o r d e r o f L.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1983451

(3)

C4-438 JOURNAL DE PHYSIQUE

Fig. 1

-

EBIC c o n t r a s t of a d i s l o c a t i o n lyxng i n c l i n e d t o surface ( i n c l i n a t i o n angle 15')

a) image s i m u l a t i o n f o r L - I c e 0 a f t e r DONOLATO /6/

b b ) EBIC micrograph (inverse cont r a s t )

f o r L sv 1000 um /2/

/

The usefulness o f the simple model o f DONOLATO f o r s e m i q u a n t i t a t i v e i n v e s t i g a t i o n s o f defect recombinat i o n p r o p e r t i e s i s demonst r a t e d i n f i g , 2 by determination o f t h e defect s t r e n g t h from c o n t r a s t c f o r two SF.

I n /7/ t h e r e was obtained an expression r e l a t i n g c o n t r a s t c t o recombinat i o n centres a t t h e d i s l o c a t i o n :

e i s the number o f centres p e r d i s l o c a t i o n length, 6 capture cgoss s e c t i o n of the centres, D the d i f f u s i v i t y o f m i n d r i t y c a r r i e r s , and V t h e i r thermal v e l o c i t

.

According t o t h e given

r e l a t i o n the pr68uct e x d can be ogtained from EBTC measure- ments if the c o r r e c t i o d f a c t o g i s known. C a l c u l a t i o n s on t h i s base show t h 3 t *cleanm d i s l o c a t i w e l l g i v e a c o n t r a s t i n t h e order o f c = 10- /7/, using b r 10-98cm' as d i s l o c a t i o n capture cross s e c t i o n as given by several authors / 8 , 9 / . Such a s m a l l c o n t r a s t i s undetectable by usual EBIC e l e c t r o n i c s . Consequently the o f t e n observed EBIC c o n t r a s t a t d i s l o c a t i o n s i s not caused by t h e dis- l o c a t i o n centres themselves. Contamination i s necessary t o cause d i s l o c a t i o n s t o appear i n contrast. Assuming t h e contaminatin

i m p u r i t i e s t o be s f f i c i e n t recombination centres w i t h b s= l ~ - ~ ~ c l p ~ (e.g. Au) a l i n e d e n s i t y o f contaminating centres o f = 200 urn-'

would be s u f f i c i e n t t o produce a c o n t r a s t c rr 5 x 10-~! That beans t h a t the existence o f EBIC c o n t r a s t i s a s e n s i t i v e measure f o r dia- l o c a t i o n ( d e f e c t ) contamination.

(4)

b f D e t e r m i n a t i o n o f P from p h o t o m e t r i c a l l y o b t a i n e d EBIC c o n t r a s t and from c a l c u l a t e d c o r r e c t i o n f a c t o r s F. I n t h e i d e a l case a f v a l u e i n d e p e n d e n t o f $ , t h e e l e c t r o n p r o b e p o s i t i o n w i t h r e s p e c t t o t h e SF c e n t r e , i s e x p e c t e d , Moreover, I' must b e indepen- d e n t o f E a n d s h o u l d b e e q u a l f o r O b o t h S F b e c a u s e o f i d e n t i c a l p r e - h i s t o r y . T h e s e e x p e c t a t i d n s w e r e s a t i s f a c t o r i l y c o n f i r m e d i n t h e r e g i o n 0 4 p 4 4

-

^SF^1,^E ⁼^{30 kev}

r

o.P3...0.27

-

^SF^1,^E ⁼^20keV

s = 0.83.. .0.29

( i n t h e l o w e r c u r v e s -a- t h e e f f e c t o f t h e c e n t r a l d e f e c t a t SF 1 was t a k e n i n t o a c c o u n t

The d e v i a t i o n s f o r $ > 9

a r e p o s s i b l y c a u s e d by d i s t u r b i n g i n f l u e n c e s o f

o 5 3 10 5 a d j a c e n t d e f e c t s .

b ^position f $urn)

-

^{SF 2 ,}^E ³⁰^keV:

r

^.^I0.90

...

^0.30

-

^SF^{2 ,}^E ⁼2 0 keV:

s

I 0Q8...0.26

T h e s e t h e o r e t i c a l r e s u l t s a r e s u p p o r t e d b e x p e r i m e n t a l i n v e s t i - g a t i o n s . F i g . 3 shows s t a c k i n g f a u l t s (SFY i n a n e p i l a y e r which w e r e c h a r a c t e r i z e d b y EBIC a n d HVEM. Some o f t h e d e f e c t s show EBIC recom- b i n a t i o n c o n t r a s t w h e r e a s f o r o t h e r d e f e c t s o n l y t h e SIRTL e t c h e d t o p o g r a p h y is v i s i b l e .

(5)

qr

a b

~ i g

.

³

-

c o r n p a r a t w e EBIC/HVEM s n v e s t s g a t z o n s o r e p i t a x i a l s t a c k i n g f a u l t s

a ) EBIC m i c r o g r a p h : o n l y b ) HVEM m i c r o g r a p h s o f t h e some o f t h e d e f e c t s same a r e a : 1-SHOCKLEY show r e c o m b i n a t i o n con- p a r t i a l s , 2 - s t a i r - r o d t r a s t ( n o t e t h a t d a r k p a r t i a l s , S c o m p l i c a t e d c o n t r a s t i s c a u s e d b y s t r u c t u r e s o f p a r t i a l s ,

t h e bounding p a r t i a l s see /3/

o f t h e SF and n o t by t h e SF p l a n e s )

With W E M t h e c r y s t a l l o g r a p h f c d e t a i l s o f t h e d e f e c t s w e r e s t u d i e d . Mo m d e r o p r s c i p i t a t e s were found a t t h e d e f e c t s .

A Pot o f s a m p l e s o f t h i s k i n d were i n v e s t i g a t e d , c o n t a i n i n g b e s i d e s S F a l s o c o m p l e t e d i s l o c a t i o n s . The r e s u l t s a r e summarized i n t a b l e 1 which i n d i c a t e s f o r e v e r y d e f e c t t y p e t h e number o f i n v e s t i g a t e d d e f e c t s and t h e number o f d e f e c t s showing EBIC c o n t r a s t . Because o f i d e n t i c a l g e o m e t r i c a l c o n d i t i o n s t h e EBIC c o n t r a s t o f t h e d i s l o - c a t i o n s c a n b e compared d i r e c t l y w i t h o u t n e e d f o r c o r r e c t i o n . Accord.

p-n d i o d e s e l e c t e d f o r EBIC i n v e s t i g a t i o n s because o f enhanced /

r e v e r s e c u r r e n t i n t h e pre-breakdown range. F i g . 4 shows d e t a i l s o f t h e d i o d e imaged b y EBIC and HVEM. A t l o w o r z e r o r e v e r s e v o l t a g e s r e c o m b i n a t i o n c o n t r a s t i s found i n t h e edge r e g i o n o f t h e d i o d e , whereas a microplasma becomes v i s i b l e a t s u f f i c i e n t l y h i g h v o l t a g e .

5 55 %

1 2 100 %

(7)

The HVEM m i c r o g r a p h r e v e a l s a dense d i s l o c a t i o n c o n f i g u r a t i o n p e n e t r a t i n g t h e m e t a l l u r g i c a l j u n c t i o n i n t h e microplasma r e g i o n . Because no d e c o r a t i o n o f t h e d i s l o c a t i o n s was found t h e recombi- n a t i o n a c t i v i t y a t t h e d e f e c t s i t e and t h e i n f l u e n c e on t h e e l e c t r i - c a l f i e l d d i s t r i b u t i o n i n t h e j u n c t i o n l e a d i n g t o t h e microplasma may be due t o t h e d i s l o c a t i o n s themselves.

On t h e c o n t r a , t h e e f f e c t o f i n d i v i d u a l d i s l o c a t i o n s i n d i o d e s o f such a r e a c a n y e n e g l e c t e d , p r o v i d e d t h e d i s l o c a t i o n i s n o t e x t r e m e l y c o n t a m i n a t e d and does n o t a c t as microplasma. T h i s i s c o n f i r m e d b y an e s t i m a t i o n o f t h e excess t h e r m a l g e n e r a t i o n c u r r e n t caused b y a d i s l o c a t i o n . A p p l y i n g DONOLATO'S c o n t r a s t c a l c u l a t i o n s /5/ and

assuming e q u a l i t y between l i f e t i m e s f o r g e n e r a t i o n and r e c o m b i n e t i o n a t t h e d i s l o c a t i o n , a p r o p o r t i o n a l i t y i s o b t a i n e d between excess t h e r m a l g e n e r a t i o n c u r r e n t and EBIC c o n t r a s t

.

A c c o r d i n g t o t h i s r e l a t i o n d i s l o c a t i o n s w i t h u s u a l EBIC c o n t r a s t a e x p e c t e d t o g i v e excess g e n e r a t i o n c u r r e n t s n o t exceeding t h e IOoB A range, w h i c h i s much t o s m a l l t o make e f f e c t s i n l a r g e s t r u c t u r e s . W i t h r e d u c t i o n o f d e v i c e dimensions, however, i n d i v i d u a l d i s l o c a t i o n s g a i n i n c r e a s i n g i m p o r t a n c e as t h e i r r e l a t i v e c o n t r i b u t i o n t o t h e d i o d e r e v e r s e c u r r e n t i n c r e a s e s

.

^,Scanning E l e c t r o n Microscopy, Vol. I, I I T R I , Chicago (1976) 529

/2/ KITTLER, M., K r i s t a l l u. T e c h n i k 15 (1980) 575

/3/ ^KITTLER, ^M. and BUGIEL, E., C r y s t a l Res. Technol. 17 (1982) 79 /4/ KITTLER, M. and SEIFERT, W., C r y s t a l Res. ~ e c h n o l . 16 (1981)157 /5/ DONOLATO, C* , O p t i k 52 (1978/79) 1 9

/6/ DONOLATO, C. and KLANN, H., 3. Appl. Phys. 51 (1980) 1624 /7/ KITTLER, M. and SEIFERT, W., Phys. S t a t . Sol.(a) (1981) 573 /8/ MAKTWANI, S., DEL PENNINO, U. and MAZZEGA, E., Proc. V. I n t e r -

n a t . Summer S c h o o l Defects, K r y n i c a / P o l a n d (1976) 225

/9/ PATEL, 3.R. and KIMERLING, L.C., 3. Physique 40 (1979) C6-79

/lo/ RAVI, K. V., VARI<ER, C.3. and VOLK, C.E., 3. Electrochem. Soc.

120 (1973) 533

/11/ HOLT, D.B., 3. Physique

-

40 (1979) C6-189