General trends in integrated circuit technology toward smaller device dimensions, lower thermal budgets, and simplified processing steps present severe physical and engineering challenges to ion implantation. These challenges, together with the need for physically based models at exceedingly small dimensions, are leading to a new level of understanding of fundamental defect science in Si. In this article, we review the current status and future trends in ion implantation of Si at low and high energies with particular emphasis on areas where recent advances have been made and where further understanding is needed. Particularly interesting are the emerging approaches to defect and dopant distribution modeling, transient enhanced diffusion, high energy implantation and defect accumulation, and metal impurity gettering. Developments in the use of ion beams for analysis indicate much progress has been made in one-dimensional analysis, but that severe challenges for two-dimensional characterization remain. The breadth of ion beams in the semiconductor industry is illustrated by the successful use of focused beams for machining and repair, and the development of ion-based lithographic systems. This suite of ion beam processing, modeling, and analysis techniques will be explored both from the perspective of the emerging science issues and from the technological challenges.
The accurate and reliable characterization of the sheet resistance of ultra-shallow (USJ) profiles is a key issue in the development of future CMOS technologies. Typically, conventional means, such as in-line four point probe measurements, have a limited accuracy due to the substrate contribution resulting from too much probe penetration, especially in the presence of highly doped underlying layers (such as well/halo-profiles). In this work, a series of advanced Boron doped layers (132 nm down to 2 nm) have been grown with Chemical Vapor Deposition (CVD) on medium and lowly doped substrates and have been characterized with a large variety of state-of-the art non-penetrating/non-contact sheet resistance tools.
A contactless method for ultrashallow junction (USJ) characterization is described based on analysis of frequency-dependent junction photovoltages from illuminated and nonilluminated areas. Relevant equations for junction photovoltages are derived. It is shown that the measured leakage current in USJ formed in halo profiles is related to space-charge region recombination.
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