Shallow junction doping technologies for ULSI

The fabrication of thin, sub-40 nm doped layers in Si with high concentrations of electrically active dopants and box-like profiles is a major technological challenge. Making these regions without introducing residual defects in the material and without affecting the properties of other material regions in the device is even more difficult. The need to control these properties of doping profiles in ultra-large-scale integrated (ULSI) circuits has driven the study of low energy implantation, transient enhanced diffusion (TED), and focused the search fornew shallow junction doping techniques. In this article, wereview the motivation for shallowjunctions, specific requirements for shallow junctions used in deep sub-micron dimension metal-oxide-semiconductor field effect transistors (MOSFETs), current understanding of implant and diffusion processes, and the state-of-the-art in low energy implantation and a number of alternate doping technologies, including plasma implantation, gas-immersion laser (GILD) doping, rapid vapor-phase doping (RVD), ion shower doping, and decaborane (B10H14) implantation.