DocumentCode :
549739
Title :
Towards 1X DRAM: Improved leakage 0.4 nm EOT STO-based MIMcap and explanation of leakage reduction mechanism showing further potential
Author :
Pawlak, M.A. ; Kaczer, B. ; Wang, Wan-Chih ; Kim, Min-Soo ; Popovici, M. ; Swerts, J. ; Tomida, K. ; Opsomer, K. ; Schaekers, M. ; Vrancken, C. ; Govoreanu, B. ; Belmonte, A. ; Demeurisse, C. ; Debusschere, I. ; Altimime, L. ; Afanas, V.V. ; Kittl, J.A.
Author_Institution :
Imec, Leuven, Belgium
fYear :
2011
fDate :
14-16 June 2011
Firstpage :
168
Lastpage :
169
Abstract :
We establish a new record low leakage (JG)-EOT for DRAM compatible MIMcap by further JG reduction to 2×10-8 (10-7) A/cm2 at 0.45 (0.40) nm EOT (0.8 V) using an improved RuOx/TiOx/Sr-rich SrxTiyOz (STO) stack. Further, for the first time we provide insight explaining the origin of the record low JG-EOT achieved, by detailed studies of our TiOx/STO stack on TiN, Ru and RuOx bottom electrodes (BE). TiOx reduces EOT on all BE (without degrading microstructure), but RuOx is needed for low JG. We prove the latter is NOT due to a work function (WF) effect, measuring -on the contrary- strong Fermi Level Pinning (FLP) at STO midgap and same e-injection barrier (~1.6 eV) from TiN, Ru or RuOx. We determine leakage is controlled by similar traps (~0.8 eV below CBE) in STO for all stacks and BE, and attribute improvement with RuOx to local STO trap density reduction by eliminating (or even reversing) oxygen scavenging effects near the electrode during crystallization. We demonstrate the potential for further JG reduction by lowering trap density, with theoretical limit for trap-free STO of 10-15 A/cm2 at EOT~0.4 nm. These results make STO a clear candidate for future DRAM.
Keywords :
DRAM chips; leakage currents; ruthenium compounds; strontium compounds; titanium compounds; DRAM; EOT STO-based MIMcap; Fermi level pinning; RuOx-TiOx-Sr; SrTiO; bottom electrodes; leakage reduction mechanism; size 0.4 nm; voltage 0.8 V; work function effect; Annealing; Crystallization; Dielectrics; Electrodes; Electron traps; Films; Tin;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
VLSI Technology (VLSIT), 2011 Symposium on
Conference_Location :
Honolulu, HI
ISSN :
0743-1562
Print_ISBN :
978-1-4244-9949-6
Type :
conf
Filename :
5984688
Link To Document :
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