Electrical reliability of parylene films for device passivation
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PARYLENE
p o l y m e r s have b e e n developed that a r e capable of b e i n g deposited a s u l t r a t h i n , c h e m i c a l l y i n e r t , and p i n h o l e - f r e e b a r r i e r l a y e r s . 1- 5 The i n t r o d u c tion of these i m p r o v e d , h i g h - p u r i t y , p o l y m e r i c f i l m s made it i m p o r t a n t to a s s e s s the f e a s i b i l i t y of e m p l o y ing these coatings as either a r e p l a c e m e n t or a n a d junct to i n o r g a n i c p a s s i v a t i o n l a y e r s or a s a b a r r i e r coating capable of m a i n t a i n i n g the s e m i c o n d u c t o r s u r face f r e e of m o i s t u r e , i o n s , and other c o n t a m i n a n t s . The p o l y m e r i c coating in d i r e c t contact with the s e m i conductor device plays a m o r e c r i t i c a l r o l e than the conventional h e r m e t i c package where the gas a m b i e n t s e r v e s as a buffer and p r o t e c t i v e agent. It was the p u r pose of this i n v e s t i g a t i o n to evaluate the s u i t a b i l i t y of using P a r y l e n e ( p o l y - p a r a - x y l y l e n e s ) as an i n s u l a t i o n b a r r i e r coating to be applied over i n o r g a n i c p a s s i v a tion l a y e r s . P a r y l e n e was chosen for this study b e cause of its unique p h y s i c a l , e l e c t r i c a l , and t h e r m a l p r o p e r t i e s f l These include the a b i l i t y to c o n f o r m p r e c i s e l y to s u b s t r a t e f e a t u r e s , i n c l u d i n g conductor edges, p r o j e c t i o n , holes, and component leads to be deposited in e x t r e m e l y thin l a y e r s , which p o s s e s s high d i e l e c t r i c s t r e n g t h . Insulation r e s i s t a n c e v a l u e s a r e achieved that a r e as high or higher than those r e p o r t e d for epoxy, s i l i c o n e , and u r e t h a n e s y s t e m s a s well as m o i s ture vapor t r a n s m i s s i o n and gas p e r m e a b i l i t y r a t e s that a r e lower than other p o l y m e r s used in e l e c t r o n i c packaging .6 VACUUM DEPOSITION O F PARYLENE Vacuum deposition e q u i p m e n t is shown in Fig. 1. It S. M. LEE and J. J. LICARI are member Technical Staff, Chemical Laboratory and Supervisor,Advanced Chemical Technology, respectively, Research and EngineeringDivision,Autonetics Division,North American Rockwell Corp., Anaheim, Calif. I. LITANTis Contract Monitor, NASA/ERC, Cambridge, Mass. This report was prepared by the Autonetics Divisionof North American Rockwell in fulfillment of NASA/ERC Contract NAS 12-2011. This manuscript is based on a paper presented at the IMD Electronic Materials Conference on August 24-27, 1969, in Boston, Mass. METALLURGICALTRANSACTIONS
c o n s i s t e d of a Vycor tube with ground g l a s s j o i n t s in a t w o - z o n e f u r n a c e . A weighed a m o u n t of a P a r y l e n e d i m e r was placed in the v a p o r i z a t i o n or p r e h e a t zone. The v a p o r s a r e conducted through the p y r o l y s i s or c r a c k i n g a r e a at about 600~ Cleavage r e s u l t s s p e c
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