An Experimental and Simulation Study of Arsenic Diffusion Behavior in Point Defect Engineered Silicon

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0994-F10-02

An Experimental and Simulation Study of Arsenic Diffusion Behavior in Point Defect Engineered Silicon Ning Kong1, Taras A. Kirichenko2, Gyeong S. Hwang3, Foisy C. Mark2, Steven G. H. Anderson2, and Sanjay K. Banerjee1 1 Microelectronics Research Center, The University of Texas at Austin, Austin, TX, 78758 2 Freescale Semiconductor Inc., 3501 Ed Bluestein Blvd, MD K10, Austin, TX, 78721 3 Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712 ABSTRACT We report that arsenic diffusion can be enhanced and retarded by surrounding interstitial rich and vacancy rich environments created by Si point defect engineering implant. The enhancement and retardation can be attributed to the dominant arsenic interstitial diffusion mechanism during post-implant anneal. Kinetic Monte Carlo simulations with newly implemented models show good match with experiments. Our study suggests the importance of arsenic interstitial mechanism and a possible approach for n-type ultra shallow junction fabrication. INTRODUCTION As the dimension of transistors in the microelectronic industry is continuously scaling down, Ultra Shallow Junction (USJ) technology has become progressively more important for fabricating the source/drain extensions in modern devices. However, the USJ fabrication is always made difficult by dopant Transient Enhanced Diffusion (TED) and deactivation by dopant clustering. Arsenic TED was conventionally considered to be of less intensity than boron TED and therefore received less attention. However, with the down-scaling of the transistors for 45nm node and beyond, the understanding and solution for arsenic TED has become more and more a research focus. In recent years, increasingly research effort has been expended on point defect engineering implant as a possible solution for TED [1]-[3]. During ion implantation, the scattering between dopant atom and Si lattice will drive the newly created interstitials into the deeper region while leaving the vacancies in the shallower region. As a result, after Si implant, a shallower vacancy-rich region and a deeper interstitial-rich region will be created in the wafer. If boron is subsequently implanted and surrounded by the shallow vacancy region, all the interstitial related boron diffusion and deactivation reactions will be suppressed by IV annihilation. To keep the vacancies in the shallow region from being annihilated by the deeper interstitials, silicon-on-insulator (SOI) wafers are often used and the buried oxide is designed to separate the interstitial and vacancy regions [4]. Boron retarded diffusion and enhanced activation have been reported by a variety of studies using this method [1]-[3]. However, it is not straightforward to transfer this technique directly from boron to arsenic. One major challenge is that unlike boron diffusion, which is almost solely enhanced by interstitial and retarded by vacancy, arsenic diffusion has been well recognized as a process with both interstitial and vacancy mechanisms [5] [6]. Traditional th

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