| AVS 54th International Symposium | |
| Electronic Materials and Processing | Wednesday Sessions |
| Session EM-WeA |
| Session: | Growth and Characterization of Complex Oxides |
| Presenter: | M. Bonvalot, CNRS, France |
| Authors: | M. Bonvalot, CNRS, France M. Kahn, CNRS, France C, Vallee, CNRS, France C. Dubourdieu, CNRS, France O. Joubert, CNRS, France |
| Correspondent: | Click to Email |
High quality MIM capacitors are seeing increased use in CMOS, BICMOS and bipolar chips. The economic demand for smaller devices directly leads to the request for higher MIM charge storage densities. Therefore new high ? dielectric materials, such as Al2O3, Ta2O5 and HfO2, are being evaluated as MIM dielectrics and are or will be used in future applications. Among those materials, it is generally admitted that Al2O3 and HfO2 show good potentials for this purpose. Al2O3 exhibits a lower k value but has a larger breakdown field than HfO2, and thus the simultaneous use of these two materials in a MIM structure may lead to some improved electrical properties. In this work, we investigated the behaviour of nanolaminate and intermixed HfO2-Al2O3 MIM capacitor structures. HfO2 and Al2O3 have both been deposited by Atomic Layer Deposition (ALD) on WSix (x=2.3) substrates. Numerous materials stackings have been realised, such as simple HfO2/WSix and Al2O3/WSix, bilayered HfO2/ Al2O3/WSix, sandwiched Al2O3/ HfO2/ Al2O3/WSix, and nanolaminate Al2O3/ HfO2/ Al2O3/ HfO2/ Al2O3/WSix, as well as intermixed (HfO2)x/( Al2O3)1-x/WSix compounds. All these structures were carefully analysed by UV ellipsometry up to 8 eV, and show an overall thickness of 13 nm. ATR and variable angle XPS analyses have been performed for interface analysis. C(V) and I(V) electrical characterizations were also carried out after metallic deposition of top electrodes (Au, Al, Ni, Pt). Comparisons of these measurements are useful for identification of individual contributions to the overall electrical behaviour of the MIM structures. In particular, we studied the gain obtained in the linearity of the C(V) curves and the overall capacitance value of these numerous MIM structures. A detailed discussion will be presented on the multiple advantages of using nanolaminate and intermixed compound structures.