Vijay Parihar

Characterization of Nickel Silicides Produced by Millisecond Anneals

Nickel silicides serve as the source, drain, and gate contact material in many advanced complementary metal oxide semiconductor (CMOS) logic applications. Nickel has demonstrated numerous advantages over Cobalt and Titanium silicides of earlier technology nodes. Traditionally, these silicides have been formed by Rapid Thermal Processing (RTP) techniques. Two separate RTP anneals are typically used to form the silicides. In this paper, we explore the formation and film characteristics of nickel silicides produced by millisecond anneals. An overview is first provided of the nickel silicide resistivities as a function of RTP anneal temperature. When plotted, this data provides the transformation curves for the RTP Soak and Spike anneals of thin nickel films. A method is described for estimating the nickel silicide activation energy using these transformation curves and, subsequently, a calculation of the requisite laser power to produce a nickel silicide of comparable resistivity. Film characteristics and morphology of the resultant nickel silicides are evaluated by Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) analysis techniques.

Defect Evolution During Laser Annealing

Implementation of millisecond annealing requires the identification of the operating conditions for that technique which minimize the residual defects. In addition, possible combinations of low temperature annealing with millisecond annealing could result in minimal residual defects. The samples studied here were implanted with Ge+ pre-amorphization and boron dopant ions and were activated with a scanning laser annealing technique with maximum temperature dwell times of about one millisecond. The laser anneal conditions were varied, along with combinations of spike anneals. The annealed samples were analyzed by plan-view transmission electron microscopy (TEM) to measure the residual defect density and size. The effects of spike temperature, laser annealing temperature, and scan rate will be discussed.

Modeling and Experiments of Dopant Diffusion and Defects for Laser annealed Junctions and advanced USJ

Laser annealed junctions and advanced ultra shallow junctions are studied in both atomistic modeling and experiments. SIMS and sheet resistance measurement for spike-RTA + Laser annealing show that additional laser annealing after spike-RTA (“+Laser”) improve the dopant activation level without increasing in junction depth. “+Laser” effect become effective in the combination of low spike-RTA temperature and high laser temperature. This effect is significant for As doped layer. Spike-RTA based junction has a limitation in viewpoint of Rs-Xj trade-off. Laser-only annealing is promising candidate to overcome this limitation. Boron diffusion with laser-only annealing is investigated. As atomistic kinetic Monte Carlo modeling show that B n I m complexes and End-of-Range (EOR) defects are formed during sub-millisecond annealing time range. Impact of F co-implant on Boron diffusion and EOR defect evolution during sub-millisecond annealing are also investigated.

Ultra shallow junctions formed by sub-melt laser annealing

Since therequirements fortheS/Dextensions forfuture devices becomemore andmoresevere withrespect toactivation andvertical abruptness, ahugeeffort hasbeendonetodevelop ultra-fast annealing techniques suchaslaser annealing. Duetothefact that onlythesurface layers areheated, theSiwafer serves asa heat sink. Hence, extremely fast cooling rates canbeobtained resulting inahigh activation andlimited diffusion ofthedopants. We present apreliminary study ontheactivation ofn-andp-type junction implants bysub-melt laser annealing. Theinfluence ofthepre-amorphization depth, thelaser annealing temperature andother process parameters ontheactivation hasbeeninvestigated. Sheet resistance andjunction depth measurements reveal goodactivation withminimal diffusion.