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The manufacturing of deep submicron devices requires the formation of very shallow, highly doped source/drain profiles. Besides the need to determine the correct atomic dopant distribution (using secondary ion mass spectrometry), there is an increasing demand for the accurate determination of the electrical carrier profiles related with the need to monitor the activation of the dopants under reduced thermal budgets. Conventional spreading resistance probe (SRP) has been widely used for this application due to its capability to measure the resistivity (and carrier) depth distribution in Si with a high geometrical resolution (nm) and high dynamic range (nine orders of magnitude). Unfortunately with the application towards very shallow profiles (junction depths less than 35 nm), the concurrent electrical resolution is influenced by several artifacts such as carrier spilling, surface damage, probe penetration, three-dimensional (3D)-current spreading, increasing correction factors, etc. From the spreading resistance roadmap presented it follows that for future sub-100 nm technologies using sub-35 nm junctions, conventional SRP is reaching its limits. As the main limitations arise from the large correction factors (in excess of 2–3000) due to the large contact size and probe separation, large bevel stepsize and probe penetration, a solution is proposed, the Nanoprofiler™ (NP), which is based on a two probe version of the scanning spreading resistance microscopy SRRM technology (small 10–20 nm tips, low force, simultaneous topography measurement), thereby reducing correction factors back to ≪10 with minimal probe penetration and extremely small stepsize. Theoretically, profiling with 0.1–0.2 nm resolution should be feasible. In view of the complexity of controlling two independent cantilevers, we will discuss the need for them on the basis of the required correction factor size and the impact of lateral (3D)-current spreading and su- - rface damage. Some of the intrinsic capabilities of the NP concept will be illustrated by experimental resistance data measured between a single SSRM tip and TiW–Au surface stripe contact at close separation. © 2002 American Vacuum Society.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures (Volume:20 , Issue: 1 )
Date of Publication: Jan 2002