High-resolution three-dimensional scanning transmission electron microscopy characterization of oxide-nitride-oxide layer interfaces in Si-based semiconductors using computed tomography.

Oxide-nitride-oxide (ONO) layer structures are widely used for charge storage in flash memory devices. The ONO layer interfaces should be as flat as possible, so measurement of the nanoscale roughness of those interfaces is needed. In this study, quantification of an ONO film from a commercially available flash memory device was carried out with a pillar-shaped specimen using scanning transmission electron microscopy (STEM) and computed tomography. The ONO area contained only low Z- and low STEM-contrast materials, which makes high-quality reconstruction difficult. The optimum three-dimensional reconstruction was achieved with an STEM annular dark-field detector inner collection angle of 32 mrad, a sample tilt range from -78° to +78° and 25 iterations for the simultaneous iterative reconstruction technique.

[1]  Sungnam Chang,et al.  Floating gate technology for high performance 8-level 3-bit NAND flash memory , 2009, ESSDERC 2009.

[2]  D. Muller,et al.  Effects of specimen tilt in ADF-STEM imaging of a-Si/c-Si interfaces. , 2008, Ultramicroscopy.

[3]  P. Midgley,et al.  TEM characterization of Ge precipitates in an Al-1.6at% Ge alloy. , 2008, Ultramicroscopy.

[4]  T. Nishi,et al.  Reduction of anisotropic image resolution in transmission electron microtomography by use of quadrangular prism-shaped section. , 2005, Journal of electron microscopy.

[5]  C. Kübel,et al.  Recent Advances in Electron Tomography: TEM and HAADF-STEM Tomography for Materials Science and Semiconductor Applications , 2005, Microscopy and Microanalysis.

[6]  P. Midgley,et al.  3D electron microscopy in the physical sciences: the development of Z-contrast and EFTEM tomography. , 2003, Ultramicroscopy.

[7]  S J Pennycook,et al.  Thin Dielectric Film Thickness Determination by Advanced Transmission Electron Microscopy , 2003, Microscopy and Microanalysis.

[8]  Yakov Roizin,et al.  Radiation-induced nitrogen segregation during electron energy loss spectroscopy of silicon oxide–nitride-oxide stacks , 2003 .

[9]  A. Verkleij,et al.  Automated high‐throughput electron tomography by pre‐calibration of image shifts , 2002, Journal of microscopy.

[10]  P. Nellist,et al.  On the origin of transverse incoherence in Z-contrast STEM. , 2001, Journal of electron microscopy.

[11]  D. Muller,et al.  The electronic structure at the atomic scale of ultrathin gate oxides , 1999, Nature.

[12]  M. Schulz.  The end of the road for silicon? , 1999, Nature.

[13]  H. Gong,et al.  Evaluation of the dielectric breakdown of reoxidized nitrided oxide (ONO) in flash memory devices using constant current-stressing technique , 1998 .

[14]  H. Engl,et al.  Regularization of Inverse Problems , 1996 .

[15]  H. Jinnai,et al.  Transmission electron microtomography without the "missing wedge" for quantitative structural analysis. , 2007, Ultramicroscopy.

[16]  Brian F. G. Johnson,et al.  Z-Contrast tomography: a technique inthree-dimensional nanostructural analysis based on Rutherfordscattering , 2001 .

[17]  Avinash C. Kak,et al.  Principles of computerized tomographic imaging , 2001, Classics in applied mathematics.

[18]  M. Kawasaki,et al.  EELS elemental mapping of a DRAM with FE-TEM , 1998 .