Using D2 Post-Deposition Anneal to Improve the Reliability of Atomic-Layer-Deposited HfO2 under Nano scaled Stresses

• Main Authors: Cheng-Hsun Liang, 梁正勳
• Other Authors: You-Lin Wu
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/10993710755363423989

碩士 === 國立暨南國際大學 === 電機工程學系 === 96 === Abstract In this thesis, we used conductive atomic force microscopy (C-AFM) in conjunction with semiconductor parameter analyzer Agilent (HP4156C), Nano-scaled stress was applied to the atomic-layer-deposited (ALD) HfO2 high-k dielectrics prepared with N2, D2, and no post-deposition anneal (PDA). The C-AFM conductive tip acting as the metal gate electrode in a traditional metal oxide semiconductor (MOS) capacitor for electrical measurements was placed in contact with the bare oxide surface directly in this work. The contact area between the tip and the sample surface is small enough that the breakdown events we measured can be considered as the intrinsic degradation and breakdown behavior of the oxide. By using the semiconductor parameter analyzer, we are able to apply either ramp voltage stress (RVS) or constant voltage stress (CVS) to the samples as well as measure the current/voltage versus time characteristics during stress. From the experimental data, we can then analyze the data statistically and make the Cumulative Failure distribution and Weibull distribution plot. Basically, the breakdown and degradation characteristics of thin oxide are a highly localized phenomenon, typically in a range of hundreds of nm2. Therefore, breakdown test using conventional MOS capacitors only gives average oxide breakdown information under the gate area. In this thesis, the contact area between the conductive tip and the oxide surface is around 300nm2, which is extremely small so that it can be considered as a single breakdown point when oxide breakdown occurs. Therefore, the Weibull plot in this work depicts the behavior of intrinsic oxide degradation and breakdown. From the experimental results, we found that the 3nm and 5nm thick ALD HfO2 oxides prepared with D2 PDA had exhibited obvious improvement in cumulative failure distribution and weibull distribution when compared with those prepared with N2 PDA and no PDA. The result indicates that D2 PDA can substantially suppress the defect generation and provide excellent interface properties. This also leads to the improved thermal stable. By D2 post-deposition anneal during the application of nano-scaled stress and improve the reliability of high-k dielectric.