Electrical Properties of Thermally Grown HfO 2 and HfO 2 /TiO 2 /HfO 2 MIM Capacitors fabricated on SiO 2 /Si Substrate
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1073-H04-31
Electrical Properties of Thermally Grown HfO2 and HfO2/TiO2/HfO2 MIM Capacitors fabricated on SiO2/Si Substrate and HfO2 MIM Capacitors Fabricated on Sapphire Bing Miao, Rajat Mahapatra, Nick Wright, and Alton Horsfall School of Electrical, Electronic and Computer Engineering, Newcastle University, Merz Court, Newcastle upon Tyne, NE1 7RU, United Kingdom ABSTRACT The scaling of contemporary metal-insulator-metal (MIM) capacitors require dielectrics of higher dielectric constant (>10), such as hafnium oxide (~18) and titanium oxide (~40). High-k dielectrics such as HfO2 and HfO2/TiO2/HfO2 have been grown by thermal oxidation to fabricate MIM capacitors on SiO2/Si substrates and on sapphire substrates also. The MIM capacitor using HfO2/TiO2/HfO2 dielectric film shows a similar frequency dependence using HfO2 dielectric on SiO2/Si substrate, while its voltage linearity coefficients, leakage current and temperature coefficient are higher than the capacitor employing HfO2 dielectric. The MIM capacitor with HfO2 dielectric fabricated on sapphire substrate shows the strongest frequency dependence, voltage linearity coefficient and temperature dependence which is related to the surface roughness. The high capacitance density of these capacitors, ranging from 5.21 fF/μm2 to 4.20 fF/μm2, meets the ITRS requirements for analog capacitor up to 2012. INTRODUCTION Capacitors are one of the essential elements in integrated circuits and are implemented expansively in many IC applications [1]. Due to high conductive electrodes and low parasitic capacitance, the metal-insulator-metal (MIM) capacitors have attracted great attention. The conventional MIM capacitors using SiO2 can provide excellent linearity properties and low temperature coefficients, however the capacitance density is low [2]. Further reduction of oxide thickness causes high leakage current and poor voltage linearity property. Therefore we must replace SiO2 with high-k dielectric materials whilst maintain the precision analog performance of these devices. There are several promising high-k candidates such as Al2O3, Sr4Ta2O9 [3], Ta2O5, HfO2 [4, 5] and TiO2 [6]. In the EOT point of view, TiO2 can be considered as one of the most potential materials to be incorporated. It is known to have relatively high dielectric permittivity; however its low band gap (~3.5eV) suggests high leakage currents. HfO2 emerged as a leading candidate due to its high dielectric constant (~22) [4], thermal stability and large band gap (~5.7eV) [5]. Based on these high-k dielectric materials, various laminate oxide structures also have been developed to overcome challenges of leakage current and electrical breakdown. Based on these high-k dielectric materials, various laminate oxide structures also have been developed to overcome challenges of leakage current and electrical breakdown [7, 8]. A new approach with dielectric laminate structure using HfO2/TiO2/HfO2 as dielectric of the MIM capacitors has been demonstrated, with a thermal grown process at 500ºC. Using this
laminate st
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