| AVS 59th Annual International Symposium and Exhibition | |
| Electronic Materials and Processing | Friday Sessions |
| Session EM+NS-FrM |
| Session: | Low-Resistance Contacts to Nanoelectronics |
| Presenter: | M.J.P. Hopstaken, IBM T.J. Watson Research Center |
| Authors: | M.J.P. Hopstaken, IBM T.J. Watson Research Center H. Wildman, IBM T.J. Watson Research Center D. Pfeiffer, IBM T.J. Watson Research Center Z. Zhu, IBM Systems and Technology Group P. Ronsheim, IBM Systems and Technology Group K.K. Chan, IBM T.J. Watson Research Center I. Lauer, IBM T.J. Watson Research Center J.S. Newbury, IBM T.J. Watson Research Center D.-G. Park, IBM T.J. Watson Research Center |
| Correspondent: | Click to Email |
Secondary Ion Mass Spectrometry (SIMS) has shown great resilience over the last decades in keeping up with the aggressive downscaling of advanced CMOS technology. Major improvements contributing to the staying power of SIMS are lower primary ion beam energies to meet the ever more stringent depth resolution demands [1] and application of novel external standard-free calibration methods for quantification in the near-surface region [2]. Here we demonstrate state-of the-art applications of SIMS to Ultra-Shallow Junction (USJ) formation and in-situ doped thin epitaxial layers.
We present As-USJ extension formation for nFET with junction depths below 120 Å, obtained using low energy ion implantation and micro-second flash (μ-flash) annealing. SIMS depth profiling employing a 200 eV Cs+ beam provides detailed information on diffusion and segregation of As at the sub-nm scale for different annealing conditions. Low energy implantation of P has been proposed as an alternative to As for the formation of Source/Drain (S/D) regions to reduce crystalline damage. This is crucially important for advanced CMOS technology based on Extremely Thin SOI or FinFET. Here, we present different analytical approaches to determine the most accurate quantification for shallow P concentration profiles in Si. Also, we have employed 3D atom probe tomography to independently determine in-depth [P] profiles for SIMS calibration purposes [3].
For pFET processes, nm-scale control of B-diffusion is instrumental to obtain highly activated and abrupt B-USJ. Here we present a novel doping strategy employing ultra-thin solid source Si:B diffusion sources –in combination with μ-flash annealing– to form the B-USJ extensions. Presence of high [B] and minimal diffusion length necessitates use of ultra low O2+ impact energy for accurate determination of junction depth and abruptness. Regarding S/D formation, In-Situ Boron Doped (ISBD) SiGe is an important technology element for pFET strain enhancement. Quantitative analysis of [B] in SiGe using reactive low energy O2+ ion sputtering is complicated due to large yield variations as a function of [Ge] [4]. We present a calibration protocol based on multiple B-implanted epitaxial Si1-xGex standards on Si(100) with constant [Ge] ranging from 20 to 50 at.%. This approach allows for explicit correction of both SiGe sputter yield and B+ and Ge+ yield variations as function of [Ge], enabling quantitative analysis of ISBD SiGe.
[1] A. Merkulov et al., JVST B 28(1) (2010) C1C48.
[2] W. Vandervorst et al., AIP Conf. Proc. 931(1) (2007) 233-245.
[3] M.J.P. Hopstaken et al, SIA, DOI 10.1002/sia.4916 (2012).
[4] Z. Zhu et al., SIA 43(1-2) (2011) 657-660.