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Formation and Properties of Roughened Poly-Si Electrodes for High-Density Drams

Published online by Cambridge University Press:  10 February 2011

H. W. Liu
Affiliation:
Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu, 300, Taiwan, ROC
Z. J. Lin
Affiliation:
Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu, 300, Taiwan, ROC
S. Y. Yu
Affiliation:
Mosel Vitelic Incorporation, Science-Based Industrial Park, Hsinchu, 300, Taiwan, ROC
S. C. Huang
Affiliation:
Mosel Vitelic Incorporation, Science-Based Industrial Park, Hsinchu, 300, Taiwan, ROC
H. C. Cheng
Affiliation:
Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu, 300, Taiwan, ROC
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Abstract

A novel structure, based upon phosphorus-implanted poly-Si films treated with phosphoric acid (H3P 4) and the standard RCA cleaning process, has been demonstrated as the bottom electrodes of DRAMs' stacked capacitors. After the H3PO4 treatment and the RCA cleaning process, micro-islands are formed on the poly-Si surface of the electrodes. For the capacitors with this novel structure, the capacitance value is 18.17 fF/μm2 and the effective oxide thickness is 18.9 Å in comparison with conventional capacitors of 5.77 fFW/μm2 and 59.5 Å. The roughened poly-Si electrode can achieve a surface enlargement of 3.15 times. The leakage current density at +1.65V and −1.65V are 7.24 × 10−8 A/cm2 and −3.31 × 10−8 A/cm2, respectively, fulfilling the requirements of 256Mb DRAMs. Weibull plots of time-zero-dielectric-breakdown (TZDB) characteristics under ramping voltage test also show tight distribution and good electrical properties. It indicates that the phosphorus-implanted poly-Si films etched by H3PO4 and then cleaned with the standard RCA process can easily and simply increase the surface area and have good electrical properties fulfilling the requirements of 256Mb DRAMs and beyond.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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