الاتصال أحادي الطبقة المنشطات من السيليكون السطوح والأسلاك المتناهية الصغر عن طريق المركبات الفوسفورية العضوية

Controlled surface doping of semiconductor structures with macroscopic areas as well as at the nanoscale is important for advanced semiconductor device architectures such as FinFet^2,3, as well as for nanostructure based devices such as nanowire-based sensors and photovoltaics^4-7. We recently introduced monolayer contact doping (MLCD) for repeatable, uniform surface doping of silicon interfaces with macroscopic and nanometric dimensions with control over dopant dose and diffusion profile¹. An important feature of MLCD is the restriction of monolayer formation to a substrate that is termed "donor substrate". MLCD simplifies some of the process steps required for Monolayer Contact Doping (MLCD) and provides complementary surface doping capabilities⁸. Once the donor substrate is loaded with the dopant containing monolayer by using self-limiting surface chemistry, the donor substrate is brought to contact with the substrate intended for doping, termed "target substrate", and both substrates are annealed while in contact. During the anneal process, dopant atoms diffuse to both donor and target substrates, and are activated at the elevated temperature. Since MLCD does not require high energy implantation of dopant atoms, no structural damage is caused to the semiconductor lattice during the process and no further anneal step is required. Good control over dopant diffusion is possible by controlling the rapid thermal process parameters. Ultra shallow and uniform dopant diffusion lengths down to a few nanometers are easily achieved. Separation of the monolayer from the process sequence simplifies the process, allow greater control over process parameters and open new possibilities for doping schemes that were not possible by using other methods. Achieving dopant level as high as the solubility limit of phosphorus in silicon is possible by multiple MLCD doping processes applied successively. In summary, traditional doping methods suffer from intrinsic limitations to fabricate ultra-shallow doping profiles. This is because of inherent statistical variations of source concentrations, overall dose and energy distribution, which are inherent to the low implantation energies required for ultra-shallow implantation. MLCD provides a simple means for surface doping, this is the result of the unique features of MLCD relying on the precise control of dopant dose and location at the atomic scale by utilizing robust surface chemistry for generating the dopant source with self-limiting monolayer chemistry formed exclusively at the semiconductor surface.