INVESTIGATION OF LANTHANIDE BASED MIM DEVICES FOR ADVANCED RF-CMOS AND ReRAM TECHNOLOGY

• Main Author: Somnath Mondal
• Other Authors: T. M. Pan
• Format: Others
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/29108745458850603171

博士 === 長庚大學 === 電子工程學系 === 101 === Innovations in modern semiconductor technology are critically dependent on the development of denser, faster and less energy consuming devices. Aggressive scaling in complementary metal-oxide-semiconductor (CMOS) devices requires a worthy development of new materials and device architectures. This research focuses on the lanthanide based high- oxide thin film for metal-insulator-metal (MIM) capacitor in Analog/Mixed-Signal (AMS) ICs and advanced nonvolatile resistive random access memory (ReRAM) applications. A large capacitance density having a low parasitic capacitance, low voltage coefficient of capacitance, and high quality factor is crucial for radio frequency (RF) and analog/mixed-signal (AMS) ICs applications in view of lower system cost, improved performance and increase in the levels of integration. Although the SiO2 and Si3N4 are commonly used dielectrics in conventional MIM capacitors, it cannot satisfy the ITRS requirements in the near future. The integration of high-k materials in present CMOS technology to realize the both high capacitance density and good voltage linearity in a cost effective way is a major challenge. In the other way, the rapid growth in modern information technology critically depends on high density nonvolatile memories but, the present charge-based memories will suffer from performance degradation as the scaling limit is approached. The development of new memory technology based on non-charge mechanism is both demanding and challenging. The high-k lanthanide oxides such as Yb2O3 and Lu2O3 are investigated systematically for MIM device applications. The Lu2O3 is found to be a very promising candidate for MIM capacitor in radio frequency and analog/mixed-signal ICs applications as it provides a high capacitance density with excellent voltage linearity. By addressing the compatibility issues of back-end-of-line (BEOL) integration in conventional CMOS technology, a low temperature and cost effective process featuring a good device performance is successfully developed. The structural, physical, and electrical characteristics are investigated with various oxide thicknesses. The transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques are used to examine the crystalline structure and quality of the oxide films. This research indicates an effective and simple way to improve the performance of high-k dielectric MIM capacitors as a promising candidate for precision circuit applications. In search of non-charge based nonvolatile memory technology, the Yb2O3 is found to be a very attractive material for applications. The evolution of resistive switching effect in metal oxide thin film is a major advantage for high density and ultra-fast memory application. However, achieving the desired characteristics and understanding the physics behind it are the main hurdles for its implementation. To overcome the above challenge, the Yb2O3 based resistance change random access memory (ReRAM) cell is successfully demonstrated. To tune the memory performance, the device fabrication process is optimized and evaluated by different method. The effect of resistive switching behavior on different metal electrodes is investigated. The combination of Ni and TaN electrode in Yb2O3 memory cell exhibits better performance compared with other electrode material. However, this method is less effective to control the memory characteristics. It is demonstrated that the doping of other metal to the memory cell effectively improve the device performance. Moreover, the effect of doping concentration on resistive switching behavior is also investigated. The possible driving mechanism of the resistive switching effect in Yb2O3 thin film is discussed. The excellent electrical characteristics of Yb2O3 memory cell indicate that it is a promising candidate for the application of high density nonvolatile memory applications. After addressing the challenges of MIM devices in different application areas, this research explore the fabrication and characterization of such devices by different high-k rare earth oxide materials for the insulator layer. MIM capacitors using Lu2O3 dielectric material is found to have better performance as compared with other high-κ materials for analog/mixed-signal (AMS) ICs applications. In contrary, the Yb2O3 thin film is promising for the next generation ReRAM applications. It is found that the oxygen vacancies in the dielectric film and the oxide/electrode interfacial layer have an adverse effect in different MIM devices.