Spreading resistance roadmap towards and beyond the 70 nm technology node

Abstract

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 spectrometry͒, 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 ͑SRP͒ has been widely used for this application due to its capability to measure the resistivity ͑and carrier͒ depth distribution in Si with a high geometrical resolution ͑nm͒ and high dynamic range ͑nine orders of magnitude͒. Unfortunately with the application towards very shallow profiles ͑junction depths less than 35 nm͒, the concurrent electrical resolution is influenced by several artifacts such as carrier spilling, surface damage, probe penetration, three-dimensional ͑3D͒-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 2-3000͒ due to the large contact size and probe separation, large bevel stepsize and probe penetration, a solution is proposed, the Nanoprofiler™ ͑NP͒, 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 measurement͒, thereby reducing correction factors back to Ͻ10 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 ͑3D͒-current spreading and surface 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.

A non‐destructive approach for doping profiles characterization by micro‐Raman spectroscopy: the case of B‐implanted Ge

“…In this regard, spreading resistance profiling (SRP) analysis is very important because it allows determining from resistivity measurements the carrier concentration profile, i.e. the concentration profile of substitutional dopant atoms . Unfortunately, in the sample preparation, SRP requires a beveling procedure that makes this technique complex and, above all, destructive.…”

Non-Conventional Characterization of Electrically Active Dopant Profiles in Al-Implanted Ge by Depth-Resolved Micro-Raman Spectroscopy

“…1) Among these, spreading resistance profiling (SRP) allows us to determine the carrier concentration profile of dopant atoms by measuring the spreading resistance vs depth on a beveled sample surface. 2) Micro-Raman spectroscopy is largely employed for the analysis of semiconductor devices, including strain characterization, local crystal orientation, and local temperature detection in devices under operational conditions. [3][4][5] For high doping levels, it is known that the first-order Raman spectrum can be heavily affected by the carrier concentration.…”

Optimization of external poly base sheet resistance in 0.13μm quasi self-aligned SiGe:C HBTs

“…Therefore small errors on the raw data can lead to significant distortions on the final carrier profile. Thus, Scanning Spreading Resistance Microscopy (SSRM), which uses much smaller contact size (5-10 nm) with much smaller correction factors [16][17][18] and hence a more accurate measurement of local active dopant concentration, was applied to characterize the boron active concentration in the thin external poly base layer during optimizing the implant conditions. The sample measured is 63 nm poly silicon layer on top of 500 nm oxide on p-type Si-substrate.…”