Paper EM-TuA9
Some High k Potential for MIM or RRAM Applications

Tuesday, October 21, 2008, 4:20 pm, Room 210

Metal Insulator Metal (MIM) capacitors in silicon analog circuit applications have attracted great attention due to their high conductive electrodes and low parasitic capacitance. Silicon oxide and nitride were commonly used in conventional MIM capacitors. Though they can provide good-voltage linearity and low temperature coefficients, their capacitance density are limited due to their low dielectric permittivity. In order to increase the surface density of MIM capacitors, several technological ways are investigated: realization of capacitors according to 3D architectures and integrating high or medium k materials. First MIM high k investigations dealt with Ta₂O₅. Among various high k dielectric materials, medium k such has HfO₂, ZrO₂ and rare earth oxides should give better performances owing to larger band gap than Ta₂O₅ and higher permittivity than silicon nitride. Flash technology is expected to reach its limits by the beginning of the next decade. In this context, existing research efforts are exploring a variety of novel memory concepts including: i) FeRAMs (Ferroelectric RAMs), ii) MRAMs (Magnetic RAMs), iii) PCRAMs (Phase Change RAMs). More recently, the semiconductor research community has shown a growing interest for RRAM (Resistive RAM) which exploits the resistive switching properties of oxides (mainly NiO) to store information. Its main advantages are good compatibility with current CMOS technology, high speed, and low power switching and good temperature stability of the data retention. A PVD process is usually used for the deposition of the oxide. Hence, for both applications (MIM capacitors and RRAM devices) high k dielectrics deposited with a low thermal budget should be a solution. This study is then focused on the deposition and characterization of several high k dielectrics such as HfO₂ or Y₂O₃ on different metallic electrodes (Pt,TiN,…) for MIM capacitors or RRAM devices. These materials are deposited by ALD or PE-MOCVD processes. The electrical behavior of the structures will be presented and discussed in terms of capacitance density, capacitance linearity and current-voltage characteristics with a special care to the switching mechanism of the high k RRAM. They will be correlated to chemical analysis results (XPS, ATR and FUV-SE), with special attention devoted to metal/oxide interface investigations.