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Title: Fabrication and characteristics of high-k MIM capacitors for high precision applications
Keywords: MIM, high-K, capacitor,plasma treatment, cancelling effect, precision applications
Issue Date: 13-Aug-2009
Citation: YANG JIANJUN (2009-08-13). Fabrication and characteristics of high-k MIM capacitors for high precision applications. ScholarBank@NUS Repository.
Abstract: The Metal-Insulator-Metal (MIM) capacitor has been proposed as the next generation capacitors for precision Radio Frequency (RF) and Analog/Mixed-Signal (AMS) ICs applications, due to its advantages of depletion?free, high?conductance electrodes and minimized capacitance loss to Si substrate. Conventional dielectric materials for MIM capacitors, such as SiO2, Si3N4, cannot satisfy the requirements of both high-quality and high-density MIM capacitors in the near future according to ITRS roadmap. The integration of high-k materials to realize high capacitance density and low Voltage Coefficient of Capacitance (VCC) in a cost effective way is imperative. In this thesis, a systematic research has been done for high-k MIM capacitors using Sm2O3 dielectric as base dielectrics. Firstly, the electrical characteristics of Sm2O3 MIM capacitors with various Sm2O3 thicknesses are investigated, including voltage linearity and leakage current density. The physical characteristics of Sm2O3 based high-k MIM capacitor is studied by using techniques such as Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS), in which the dielectric constant, crystalline structure are examined. Secondly, the effects of Plasma Treatments (PT) with O2 and/or N2 on the performance of MIM capacitors with Sm2O3 dielectric are investigated. It will be shown that plasma treatment after Sm2O3 dielectric formation can effectively reduce both the quadratic and linear VCC, hysteresis. Also the leakage current density can be significantly improved. These results indicate that plasma treatment after dielectric formation is an effective way to improve the performance of high-k dielectric MIM capacitors for precision circuit applications. The excellent electrical characteristics of Sm2O3 MIM capacitors indicate that it is a promising candidate for the application of high-k dielectric MIM capacitors. Thirdly, the MIM capacitors of Sm2O3 stacked with a thin SiO2 layer to modulate the effective VCC are investigated. By using the ?cancelling effect? of the positive quadratic VCC of Sm2O3 and the negative quadratic VCC of SiO2, MIM capacitors with high capacitance density, low quadratic VCC and leakage current density are successfully demonstrated. Such ?cancelling effect? of SiO2 and Sm2O3 dielectrics can be further optimized to obtain higher capacitance density and near zero quadratic VCC. Finally, a systematic study of the influence of metal electrodes on the performance of Sm2O3 MIM capacitors is performed. The improvement of electrical characteristics is demonstrated by using high work-function metal electrodes while low work-function metal electrodes show negative effects. The possible reasons of the interfacial layer formation are discussed.
Appears in Collections:Ph.D Theses (Open)

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