C e n t r a l R e s e a r c h L a b o r a t o r y , H i t a c h i L t d . Kokubunji, Tokyo 185, Japan A v e r y h i g h d e n s i t y dRAM c e l l named CCC h a s b e e n s u c c e s s f u l l y d e v e l o p e d . The c e l l having t h e c o n v e n t i o n a l o n e -t r a n s i s t o r t y p e c o n f i g u r a t i o n f e a t u r e s i t s n o v e l c a p a c i t o r w h i c h i s formed i n a d r y e t c h e d moat i n t o S i s u b s t r a t e . A s t h i s c a p a c i t o r e x t e n d s i n t o t h e s u bs t r a t e , a l m o s t i n d e p e n d e n t i n c r e a s e i n c a p a c i t o r v a l u e i s a c h i e v e d w i t h o u t c e l l area enlargement. A s a r e s u l t , t h e v a l u e o f 6 0 f F h a s b e e n o b t a i n e d w i t h 3x7um2 c e l l and a 4~m deep moat. A c a p a c i t o r i n s u l a t o r i s a t r i p l e l a y e r o f S i 0 2 / S i N / S i 0 2 o f w h i c h t o t a l t h i c k n e s s i s e q u i v a l e n t t o 15nm s i n g l e l a y e r S i 0 2 . No p r o b l e m h a s b e e n f o u n d c o n c e r n i n g t h e i n s u l a t o r i n t e g r i t y a n d m i n o r i t y c a r r i e r l i f e t i m e s u s c e p t i b l e t o p o s s i b l e d r y e t c h ' s d a m a g e s . A punchthrough current from one moat to the o t h e r h a s b e e n f o u n d t o b e t h e b i g g e s t o b s t a c l e h i n d e r i n g c l o s e r p a c k i n g o f a d j a c e n t m o a t s . D e s i g n r u l e s f o r t h e p a c k i n g h a v e b e e n d e r i v e d f r o m t w o -d i m e n s i o n a l d e v i c e s i m u l a t i o n (CADDET) i n o r d e r t o k e e p s t o r e d c h a r g e s . An o b t a i n e d S/N r a t i o i s l a r g e e n o u g h t o g e t v e r y s t a b l e dRAM o p e r a t i o n a n d h i g h immunity t o a l p h a -p a r t i c l e s f o r m e g a b i t dRAM's. On t h e b a s i s o f t h e CCC c o n c e p t , f u r t h e r i n t e g r a t i o n of denser packing has been under development.
In this paper, the key features and results of the new advanced electron beam (c-beam) reticle writing system HL-900M are shown. This new system, based on HL-800M techno1ogy', has been improved from the both sides of hardware and software with introducing some new technologies. The new electron beam optical column has been introduced to keep enough stability against environmental fluctuations. X-Y stage mechanism and high precision temperature control system have been refreshed to promise highly positioning accuracy. Parallel processing exposure function makes throughput improved even with handling the huge amount of data, such as over 20 Gbytes in the standard specification system. As some results of evaluation tests, the critical dimension (CD) accuracy of 12 nm (3cr), the pattern positioning accuracy of 25 nm (3cr) and the stitching accuracy of 15 nm (Imeanl+3) were obtained. The total performance of this system is satisfied with the specification of the 0. I 8-0. 15 jim node reticles on production levels and development of 0. 13 tm node reticles.
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