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11 August 1999 Capping layers, cleaning method, and rapid thermal processing temperature on cobalt silicide formation
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The effect of some key variables such as rapid thermal processing (RTP) temperature, substrate cleaning method and capping layers, on cobalt silicide formation has been investigated. The in-situ RF sputter etch is found to give a post RTP2 Rsh that is equivalent to a wet cleaned wafer. The temperature transformation curve of cobalt films, analyzed with Rsh data and XRD, reveal the formation of Co2Si-CoSi-CoSi2 phases in that order. The transformation curves of TiN capped films match those of blanket cobalt but the Ti capped films show the CoSi phase to be stable over a broader temperature range. There is no effect of dopants on the final cobalt disilicide Rsh values for either the single of polycrystalline substrates. Controlled oxygen leak studies in the RTP ambient reveal that the Rsh after RTP1 is degraded if a capping layer is not present. Electrical test results confirm the need for capping layers. This is indicated by lower Rsh and Rc values on both n+ and p+ junctions and poly structures. Furthermore the electrical results are comparable for Ti and TiN layers used as the cap films although the Rsh/Rc values are in general lower for the TiN capped films. Poly gate length vs Rsh plots show the extendibility of the capped cobalt silicide process to the 0.18 um node.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dinesh Saigal, Gigi Lai, Lisa Yang, Jingang Su, Ken Ngan, Murali K. Narasimhan, Fusen E. Chen, Ajay Singhal, Dave Lopes, Sean Lian, Wanqing Cao, Kevin Tsai, Patrick Lo, Shih-Ked Lee, and James Shih "Capping layers, cleaning method, and rapid thermal processing temperature on cobalt silicide formation", Proc. SPIE 3883, Multilevel Interconnect Technology III, (11 August 1999);

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