The Role of Surface Annihilation in Annealing Investigated by Atomic Model Simulation
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The Role of Surface Annihilation in Annealing Investigated by Atomic Model Simulation Min Yu1, Xiao Zhang1, Ru Huang1, Xing Zhang1, Yangyuan Wang1, Jinyu Zhang2, Hideki Oka3 1.
Institute of Microelectronics, Peking University, China 100871 Fujitsu R&D Center Co. LTD, Room B1003, Eagle Run Plaza No.26 Xiaoyun Road Chaoyang District Beijing, China 3. Fujitsu Laboratories LTD, 10-1 Morinosato-Wakamiya, Atsugi 243-0197, Japan 2
Abstract Behavior of point defects in annealing is investigated a lot in order to suppress the Transient Enhanced Diffusion (TED) of boron as is urged by the development of integrated circuits. Surface annihilation possibility for point defects is very important in determining junction depth in the case of ultra-shallow doping. However the understanding on it is still ambiguous considering the inconsistent results on surface annihilation behavior. In this paper the variation of surface annihilation possibility is studied. The simulation on boron diffusion as well as silicon diffusion is performed. The evolution of Si clusters is simulated. By explaining experimental results with Kinetic Monte Carlo method based simulation, we proposed that surface annihilation possibility varies in different cases.
Introduction Shallow junction technology requires more accurate control of junction depth and sheet resistant than before. The transient enhanced diffusion (TED) and inactivation of boron in post-implant annealing is the main barrier for shallow junction technology in IC fabrication. In recent years, these phenomena have been deeply studied. The enhanced diffusion is attributed to the evolution of extended defects, which releases Si interstitials and thus drives the diffusion of boron. Inactivation of B is explained in terms of the formation of B-Si clusters. It is believed that point defects are removed from silicon wafer through the surface. The surface annihilation possibility is important in determining total diffusion amount and thus junction depth. However inconsistent results on surface annihilation possibility still exist [1], which makes it difficult to understand the underlying mechanism. In this paper, the surface annihilation possibility is studied through the Kinetic Monte Carlo (KMC) method annealing simulation. The diffusion of boron and Si after implantation is simulated. Evolution of Si clusters is also simulated. The simulation results are verified by experiments. It is proposed that the surface annihilation possibility varies with different surface conditions.
Models The simulation method applied here is KMC [2]. Only defects are included in the simulation and modeled as particles. Defects considered are Si interstitials (I), vacancies (V), dopants and clusters, such as Si clusters (In), vacancy clusters (Vn) and B-Si clusters (BnIm). The simulation box is defined as the simulation area as is shown in figure 1. Box surfaces parallel to Z axis are set as periodical boundaries, i.e. particles that go out of
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Top surface Wafer surface
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