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HYDROGEN PASSIVATION OF Si(100) BY REMOTE HYDROGEN PLASMA TREATMENT

T. Hsu, B. Anthony, L. Breaux, R. Qian, S. Banerjee, and A. Tasch Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78712 S. Lin and H. L. Marcus Center of Materials Science and Engineering, The University of Texas at Austin, Austin, Texas 78712 ABSTRACT Hydrogen passivation of the Si(100) surface prepared by a two-stage remote hydrogen plasma treatment has been investigated using Auger Electron Spectroscopy (AES) and Reflection High Energy Electron Diffraction (RHEED). AES analysis was employed to examine the degree of passivation at different temperatures by monitoring the level of impurities, mainly oxygen and carbon, readsorbed on the Si surface after exposure to air for two hours. RHEED analysis was used to investigate the reconstructed surface structure and the results were correlated with the results of AES analysis. It was found that better Si surface passivation is achieved at a lower substrate temperature during the remote hydrogen plasma treatment. Silicon epitaxial growth by Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD) was attempted on the H-passivated Si(100) at 305°C. It was found that epitaxial growth is achievable on these wafers even after 2 hours air exposure without further cleaning prior to growth. We have also observed for the first time electron-beam-induced oxygen adsorption on the Si surface prepared by remote hydrogen plasma clean and have confirmed this by Scanning Auger Microscopy (SAM) at various electron beam current densities. The adsorption of oxygen and carbon on the H-terminated Si surface from the ambient upon 3 keV electron beam irradiation is believed to be associated with either the breakage of the Si-H bond or rearrangement of bonding between Si, H, and 0, resulting in a loss of hydrogen passivation. INTRODUCTION Hydrogen passivation of the silicon surface has become an area of research of considerable interest because of its applicability to low temperature processing in semiconductor fabrication. A highly critical part of low temperature processing is the achievement of a clean Si surface and retention of surface integrity for subsequent processing. Hydrogen passivation serves the purpose of preventing readsorption of contaminants on the Si surface by satisfying the dangling bonds on a clean Si surface[I,2]. Since thermal desorption of the adsorbed hydrogen from a Si surface is known to occur at temperatures above 460°C[3], this hydrogen-terminated Si surface can be particularly useful in low temperature processing. Several techniques have been reported for preparation of a H-terminated Si surface [4-8]. In our study, a remote hydrogen plasma clean, which serves as an in situ cleaning step for subsequent epitaxial growth by RPCVD, is employed to achieve both surface cleaning and passivation. During the cleaning, hydrogen gas is flowed through a plasma column and excited by a 13.56 MHz r-f source to produce atomic hydrogen which is then transported to the wafer sur