Title :
Ta/sub 2/O/sub 5/ capacitors for 1 Gbit DRAM and beyond
Author :
Kwon, K.W. ; Park, I.-S. ; Han, D.H. ; Kim, E.S. ; Ahn, S.T. ; Lee, M.Y.
Author_Institution :
Semiconductor R&D Center, Samsung Electron. Co. Ltd., Kyungki, South Korea
Abstract :
A thermally robust Ta/sub 2/O/sub 5/ capacitor applicable to the 1 Gbit DRAM and beyond was developed. From the degradation-free Ta/sub 2/O/sub 5/ capacitor with a TiN/poly-Si top electrode, the sputtered-TiN was replaced by the PECVD-WN to improve the step coverage for the complicated capacitor structure. The Ta/sub 2/O/sub 5/ capacitor with a PECVD-WN/poly-Si top electrode had a better thermal stability in the complicated capacitor structure than that with sputtered-TiN/poly-Si, as a result. Capacitance of more than 90 fF/cell and leakage current lower than 2/spl times/10/sup -15/ A/cell were obtained by applying the WN/poly-Si top electrode and a 3.5 nm Ta/sub 2/O/sub 5/ capacitor dielectric to a cylindrical capacitor with rugged poly-Si surface (projection area=0.4 /spl mu/m/sup 2/). TDDB measurement predicted longer lifetime than 10 years at the device operating voltage. This new capacitor structure, therefore, surpasses the requirements for the 1 Gbit DRAM.<>
Keywords :
DRAM chips; capacitance; capacitor storage; chemical vapour deposition; electrodes; leakage currents; semiconductor technology; tantalum compounds; thermal stability; thin film capacitors; 1 Gbit DRAM; 1 Gbit/s; 10 y; 3.5 nm; 90 fF; PECVD-WN; Si; Ta/sub 2/O/sub 5/; Ta/sub 2/O/sub 5/ capacitor dielectric; Ta/sub 2/O/sub 5/ capacitors; TiN; TiN/poly-Si top electrode; WN/poly-Si top electrode; capacitor structure; cylindrical capacitor; degradation-free Ta/sub 2/O/sub 5/ capacitor; leakage current; lifetime; projection area; rugged poly-Si surface; sputtered-TiN; step coverage; thermal stability; thermally robust; Capacitance; Capacitors; Dielectrics; Electrodes; Leakage current; Random access memory; Robustness; Thermal degradation; Thermal stability; Tin;
Conference_Titel :
Electron Devices Meeting, 1994. IEDM '94. Technical Digest., International
Conference_Location :
San Francisco, CA, USA
Print_ISBN :
0-7803-2111-1
DOI :
10.1109/IEDM.1994.383295
