Non-routine Dopant, Impurity and Stoichiometry Characterization of SiGe, SiON and Ultra-low Energy B-implanted Si Using
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Non-routine Dopant, Impurity and Stoichiometry Characterization of SiGe, SiON and Ultra-low Energy B-implanted Si Using Secondary Ion Mass Spectrometry Charles W. Magee, Temel H. Buyuklimanli, John W. Marino, Steven W. Novak and M. Alper Sahiner Evans East (A member of the Evans Analytical Group) 104 Windsor Center Drive, Suite 101, East Windsor, New Jersey 08520 USA ABSTRACT New, non-routine metrology issues are addressed for three kinds of materials and processes that are necessary for the fabrication of ultra-high speed devices. We look at the problems and solutions for measuring both stoichiometry and dopant content of SiGe material when using Cs primary ion bombardment. We examine the challenges of determining the N content of ultra-thin SiON gate dielectrics with emphasis on what will be necessary for the measurement of 1nm thick oxides. And finally we show some promising early results of using a new protocol for measuring ULE B ion implant profiles in the top 3nm with emphasis on obtaining a more realist profile shape in this region for TCAD modeling purposes. INTRODUCTION As device dimensions shrink, new materials, new processes and novel device structures are needed to obtain the device speed that will be needed in the near and foreseeable future. These new materials and structures oftentimes require new methods of characterization. This is certainly the case with Si-based high-speed bipolar and fieldeffect transistors being planned for future CMOS and BICMOS technologies. This manuscript will illustrate three examples of how new metrology methods using secondary ion mass spectrometry (SIMS) have been devised to support the new materials and technologies that are in use now or will be needed in the near future. STOICHIOMETRY AND IMPURITY ANALYSIS IN SiGe HBTs SiGe is being used currently in the base region of bipolar transistors to increase the speed of devices, and may be used in the future for fabrication elevated source-drains in FETs [1]. Not only does one have to measure the Ge content of the thin layers that are used in these structures, but one must also perform accurate measurements of the dopants and impurities as well. These measurements are complicated when using SIMS because the matrix is no longer a virtually pure material, i.e. 100% Si, but an alloy of Si and Ge with from 5 to 50% Ge. What is more, the Ge composition of the SiGe layers used in HBTs is usually not constant, but graded in composition through the thickness of the base layer. In some cases, this graded Ge composition requires one to make a point-by-point correction for the sensitivity factors for dopants and impurities that takes into account the Ge concentration at every data point. The necessity for applying such correction factors is based on the results from calculating relative sensitivity factors (RSFs) from a series of reference materials of single layers of SiGe that were ion implanted with B, P, C and O. C6.1.1/B9.1.1 Downloaded from https://www.cambridge.org/core. University of Cambridge, on 02 Feb 2020 at 23:28:16, subj
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