Microstructure Characterization for Nano-thickIr-inserted Nickel Silicides

Abstract

Department of Materials Science and Engineering, University of Seoul, Cheonnong-dong, Tongdaemun, Seoul 130-743, KoreaElectrical Engineering, Unversity of Texas at Dallas, 2601 N. Floyd Rd., Richardson, TX 75083, USA(2007 1 23 , 2007 4 11 )Abstract We fabricated thermally-evaporated 10 -Ni/(poly)Si and 10 -Ni/1 -Ir/(poly)Si structures to investigatethe microstructure of nickel monosilicide at the elevated temperatures required for annealing. Silicidesunderwent rapid at the temperatures of 300~1200 for 40 seconds. Silicides suitable for the salicide processformed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point testerwas used to investigate the sheet resistances. A transmission electron microscope(TEM) and an Auger depthprofile scope were employed for the determination of vertical section structure and thickness. Nickel silicideswith iridium on single crystal silicon actives and polycrystalline silicon gates showed low resistance up to 1000and 800, respectively, while the conventional nickle monosilicide showed low resistance below 700. ThroughTEM analysis, we confirmed that a uniform, 20 -thick silicide layer formed on the single-crystal siliconsubstrate for the Ir-inserted case while a non-uniform, agglomerated layer was observed for the conventionalnickel silicide. On the polycrystalline silicon substrate, we confirmed that the conventional nickel silicideshowed a unique silicon-silicide mixing at the high silicidation temperature of 1000. Auger depth profileanalysis also supports the presence of thismixed microstructure. Our result implies that our newly proposediridium-added NiSi process may widen the thermal process window for the salicide process and be suitable fornano-thick silicides. Key wordsNiSi, Ir-inserted Nisilicide, TEM, Auger depth profiling.