Hironaru Yamaguchi

A Novel Feature of Neutron-Induced Multi-Cell Upsets in 130 and 180 nm SRAMs

Bit-multiplicity of neutron-induced single event upsets (SEU) in CMOS SRAMs formed with 130 and 180 nm technologies was analyzed using mono-energetic, quasi-mono-energetic, and spallation neutron sources in various accelerator facilities. The energy dependence of the ratio of multi-cell upsets (MCUs) to the total number of upsets can be described by a Weibull-type function with the threshold energy of the MCU. The 130 nm SRAMs show a novel feature of multi-cell upsets (MCUs) including frequency distribution of the multiplicity of error bits. In the case of the 130 nm SRAM, the probability function of the MCU can be expressed as a sum of exponential and Lorentzian functions of the multiplicity of error bits. According to previous results of 3-dimensional device simulation, the Lorentzian component can be due to bipolar action.

Temperature measurement of Al metallization and the study of Black's model in high current density

The temperature of 1 micrometer dia spot on a conductor was measured for the first time and compared with the predictions of the simulation model and with the data obtained by the line resistance method. Experiments were carried out to determine the dependence of electromigration lifetime on current density and temperature with an accurate measurement of temperature. These data support that the parameters of Blacks model are constant at low as well as high current density range.

Fine Structure of Porous Si with Visible Photoluminescence

Porous Si formed by anodization is studied by means of high-resolution scanning electron microscopy, optical microscopy, microphotoluminescence spectroscopy and micro-Raman spectroscopy. Surface morphologies of porous Si films are varied by changing the anodization conditions. High-resolution scanning electron microscopy measurements show that in all these films, porous Si fine structures of visible photoluminescent regions, which are confirmed with optical microscopy and micro-photoluminescence spectroscopy, are composed of particlelike structure of various sizes from several nm to several tens of nm. The peak of the Raman spectrum from the particlelike structure is shifted to lower energy and is wider than that for bulk Si, possibly due to lattice expansion around large surface fractions. Visible photoluminescence in porous Si is not due to carrier confinement in quantum wires, but is probably due to carrier confinement in this structure.

Single event effects as a reliability issue of IT infrastructure

Terrestrial neutron is being recognized as a major source of single event effects (SEEs) including soft-error of semi-conductor devices at the ground level. As semiconductor device scaling nose-dives into sub 100nm, the possible threat from single event effects is apparently growing onto IT systems that require a great number of electron devices. The modes of SEEs, however, are reportedly diverging on annual base and thus methods to quantify such effects are getting more and more complicated even for device level. In the present paper, current situation on neutron-induced SEEs are reviewed and benchmark studies are proposed to make the effects of SEEs on the reliability of IT infrastructure clear.

Crystal Growth of Laser Annealed Polycrystalline Silicon as a Function of Hydrogen Content of Precursors

The influence of hydrogen in a precursor on excimer laser crystallization behavior was investigated. The crystal orientation and lattice constant of polycrystalline silicon films were analyzed by X-ray diffraction measurement. An intensity ratio of 111 to 220 was used as an index of the (111) preferred orientation. A randomly oriented film with an index of 2 at lower energy density changed to the highly (111) oriented phase with an index of more than 15 at higher energy density. It was observed in the PE-CVD films that increasing the hydrogen in the precursor films decreased the orientation index. The lattice constant of the laser-annealed PE-CVD silicon was found to be larger than that of the PVD silicon and to decrease with an increase in laser energy density. The network structure of as-deposited PVD film with less hydrogen content was denser than that of as-deposited PE-CVD. The network structure of the precursor strongly affected the crystal growth, and the structure of the ELC poly-Si was still affected by the precursors, even though the hydrogen content decreased after laser annealing.