Dielectric and interface properties of pyrolytic aluminum oxide films on silicon substrates
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J[~ECENTLY, t h e r e h a s been i n c r e a s i n g i n t e r e s t in the use of a l u m i n u m oxide as g a t e - i n s u l a t o r and p a s s i v a t i n g d i e l e c t r i c in s i l i c o n d e v i c e s . The p o t e n t i a l a d v a n t a g e s of these f i l m s o v e r the m o r e c o n v e n t i o n a l l y used SiO2 films are:higher dielectric constant, greater imperm e a b i l i t y to i m p u r i t y d i f f u s i o n , l o w e r r a d i a t i o n s e n s i t i v i t y , and the r e l a t i v e l y low t e m p e r a t u r e s r e q u i r e d for device f a b r i c a t i o n . The fact that A1203-Si s t r u c t u r e s , p r e p a r e d by c h e m i c a l v a p o r d e p o s i t i o n of A1203, have a s s o c i a t e d positive flatband voltage v a l u e s 2 s t i m u l a t e s additional i n t e r e s t . S e v e r a l m e t h o d s have been r e p o r t e d for the p r e p a r a tion of A12Os f i l m s by c h e m i c a l v a p o r d e p o s i t i o n . D e position f r o m the CO2-H2-Al~C16 r e a c t i o n m i x t u r e at 850 ~ to 1200~ has been studied by s e v e r a l i n v e s t i g a t o r s . 3-7 The use of o r g a n o - a l u m i n u m s t a r t i n g m a t e r i a l s p e r m i t s d e p o s i t i o n of A12Os f i l m s at l o w e r s u b s t r a f e t e m p e r a t u r e s . Among the m e t h o d s used a r e : p y r o l y s i s of a l u m i n u m a c e t y l a c e t o n a t e at 480~ pyrolys i s of a l u m i n u m t r i e t h o x i d e at 300 ~ to 500~ 9-1' the oxidation of t r i - i s o b u t y l a l u m i n u m with oxygen at 250 ~ to 500~ and the oxidation of t r i m e t h y l a l u m i n u m with oxygen o r n i t r o u s oxide .,3,14 The method used in this work is the p y r o l y s i s of a l u m i n u m t r i - i s o p r o p o x i d e 1 and is an e x t e n s i o n of the work p r e v i o u s l y r e p o r t e d in Ref. 2. EXPE RIME NT AL Deposition P r o c e s s T h i n d i e l e c t r i c f i l m s of a l u m i n u m oxide have b e e n deposited on s i l i c o n s u b s t r a t e s by the p y r o l y s i s of r e cry s t a l l i z e d A1- isopropoxide . " 2 T h e v a p o r s we re t r a n s p o r t e d to the r f - h e a t e d 'S s u b s t r a t e s by b u b b l i n g h e l i u m through the m o l t e n m e t a l - a l c o h o l a t e at 125~ to 130~ T h i s gas s t r e a m was s u b s e q u e n t l y mixed with n i t r o g e n c a r r i e r gas and d e p o s i t i o n s w e r e p e r f o r m e d M. T. DUFFY, J. E. CARNES, and D. RICHMAN are Members of the Technical Staff, RCA Laboratories, Princeton, N. J. This manuscript is based on a paper presented at the annual conference sponsored by the Electronic Materials Committee of the Institute of Metals Division of the MetallurgicalSociety of AIME and held August 30-September 2, 1970, in New York City. METALLURGICALTRANSACTIONS
both in the p r e s e n c e and a b s e n c e of oxygen. The d e p o s i t i o n t e m p e r a t u r e was u s u a l l y 500~ ( s u s c e p t o r t e m p e r a t u r e ) . The e x p e r i m e n t a l a r r a
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