Millisecond laser annealing is used to fabricate ultra shallow arsenic junctions in preamorphized and crystalline germanium, with peak temperatures up to 900°C. At this temperature, As indiffusion is observed while yielding an electrically active concentration up to 5.0 ϫ 10 19 cm −3 for a junction depth of 31 nm. Ge preamorphization and the consecutive solid phase epitaxial regrowth are shown to result in less diffusion and increased electrical activation. The recrystallization of the amorphized Ge layer during laser annealing is studied using transmission electron microscopy and spectroscopic ellipsometry.Germanium has received considerable attention in the last decade as a promising channel material for high performance logic applications. However, as scaling continues the source/drain resistance gains in importance. 1,2 Consequently, ultra shallow and low resistive junctions are required for the integration into very-large scale integration circuitry.Shallow, low resistive p-type junctions ͑using B or Ga as acceptors͒ can be attained using optimized solid phase epitaxial regrowth ͑SPER͒ and rapid thermal annealing ͑RTA͒ schemes. 3,4 In contrast, donors such as P or As show high concentration-enhanced diffusion; 5 a mechanism which has been consistently explained by mobile, negatively charged dopant-vacancy pairs. 6 The fabrication of ultra shallow junctions therefore requires a limited thermal budget ͑low temperature or fast anneal͒, while a high temperature is still needed to achieve a high electrically active concentration. These two competing requirements have led to the use of ultrafast heattreatment methods such as flash-assisted annealing 7-9 and millisecond laser thermal processing. Previously, laser annealed P junctions in Ge ͑X J Ͼ 70 nm͒ were investigated. 10,11 In this work, we investigate the feasibility of laser annealing to fabricate ultra shallow, low resistive As junctions in germanium. More specifically, the effects of the laser peak temperature and the combination with a preamorphization implant are studied.As junctions were fabricated using p-type, 300 mm, ͑100͒-oriented Si wafers on which a relaxed epitaxial Ge was grown ͑1.5 m thick, threading dislocation density Ϸ2 ϫ 10 7 cm −2 ͒ and capped with 2 nm of GeO 2 ͓which was stripped preceding secondary-ion mass spectroscopy ͑SIMS͒ and micro four-point probe tool ͑u4PP͒ analysis͔. The wafers received a boron well doping up to 3 ϫ 10 17 cm −3 , followed by a Ge preamorphization implant ͑PAI-Ge 20 keV, 2 ϫ 10 14 cm −2 ͒ on selected samples, yielding an amorphous layer of 25 nm. As was implanted at an energy of 5 keV ͑5 ϫ 10 14 cm −2 ͒. The samples then received millisecond laser annealing. The laser spot measures 1.1 cm ϫ 75 m and scans the wafer at a speed of 75 mm/s ͑two consecutive scans͒. A wafer preheating is applied ͑250°C͒ to reduce thermal stress arising from the localized laser heating. No absorber layer was deposited to assist in the laser anneal. Multiple regions ͑each measuring at least 5 ϫ 5 cm͒ were illuminated, whereby the laser ...

Whereas the introduction of 3D-dimensional devices such as FINFET's may be a solution for next generation technologies, they do represent significant challenges with respect to the doping strategies and the junction characterization.Aiming at a conformal doping of the source/drain regions in a FINFET in order to induce a conformal under diffusion and homogenous device operation, one can quickly recognize that classical beam implants fail to fulfill these needs, in particular when considering closely spaced fin's. Indeed the effects of different implant angles (top vs bottom) and the concurrent variation in projected range, dose retention and sputtering as well as the effect of the wafer rotation when tilting is used, all lead to a non-conformal doping. Alternative processes such as vapor phase deposition (VPD) or plasma doping are presently being considered, as they hold the promise of conformality. Using VPD or Atomic Layer Doping dopant atoms are deposited on the surface through thermal decomposition of typical chemical vapor deposition precursors and are subsequently in diffused. Good conformality (~ 93 % for sidewall vs. top dose), defect free junctions and high activation levels are the positive points of this process. Plasma immersion doping is an alternative approach which is easier to integrate (similar to ion implantation) and suitable for p-and n-type doping. Whereas it holds the promise of conformality when implanting large macroscopic features, the latter is far less obvious when trying to dope microscopic feature conformally. In fact the formation of conformal junctions in FINFET's with plasma based processes is quite challenging and relies on secondary processes such as resputtering, deposition and in diffusion etc. Their optimization is compromised by concurrent artifacts, sputter erosion being the most important one. In support of these developments the measurement and identification of conformality adequate metrology is required. For this purpose we have extensively used Scanning Spreading Resistance Microscopy (SSRM) as a means to characterize the vertical/lateral junction depths, the concentration levels and the degree of conformality. Characterization of the (3D)-underdiffusion can be achieved by a dedicated SSRM experiment and/or the Tomographic Atomprobe. As a complement to the SSRM technique we also developed a concept based on resistance measurements of fin's which allows to map the sidewall doping across the wafers and provides fast feedback on conformality.

A solution for conformal n-type finFET extension doping is demonstrated, yielding I ON values of 1.23 mA/µm at I OFF =100 nA/um at 1V. This high device performance results from 40% reduced external resistance, which in term is stemming from 130% increased fin sidewall doping (confirmed by SIMS, SSRM and Atom Probe) relative to ion implant process. In this work we also report lowered gate leakage due to the damagefree extension doping. Introduction and need for conformal doping

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