Moriya Miyashita

Improvement of thin oxide quality by hydrogen annealed wafer

Drastic improvement of a wafer quality has been carried out by high temperature anneal in hydrogen. A thin oxide formed on the hydrogen annealed wafer (HAI) has been found to have excellent behavior. In addition, electrical and physical evaluations verify that the HAI wafer does not have any disadvantage compared to the CZ wafer. The HAI wafer is promising for the substrate used in ULSI manufacture.<<ETX>>

Impacts of Surface Roughness Reduction in (110) Si Substrates Fabricated by High-Temperature Annealing on Electron Mobility in n-Channel Metal--Oxide--Semiconductor Field-Effect Transistors on (110) Si

The effects of high-temperature Ar/H2 annealing on (110) Si, which is known to provide flat (110) Si surfaces, have been studied from the viewpoint of metal–oxide–semiconductor (MOS) interface roughness and inversion-layer electron mobility limited by surface roughness scattering in (110) Si n-channel metal–oxide–semiconductor field-effect transistors (n-MOSFETs). It has been confirmed by quantitative transmission electron microscope (TEM) analysis that the reduction in the surface roughness on (110) Si is still maintained after gate oxidation with gate oxide thickness (Tox) of 6.9 nm. The mobility measurement of (110) Si n-MOSFETs fabricated using Si wafers with high-temperature Ar/H2 annealing has revealed that the high-temperature annealing increases the electron mobility of (110) Si MOSFETs at 10 K by 14 and 5.7% for Tox values of 6.9 and 8.9 nm, respectively, and increases the electron mobility at 300 K by 2.5 and 0.72% for Tox values of 6.9 and 8.9 nm, respectively. The Tox dependence of the enhancement factor might be attributable to the increase in MOS interface roughness with increasing Tox. It has also been observed that the mobility enhancement factor is slightly dependent on the channel direction. The mobility increase has been observed to be greater along than along .

Impacts of Surface Roughness Reduction in (110) Si Substrates by High Temperature Annealing on Electron Mobility in n-MOSFETs on (110) Si

Temperature Annealing on Electron Mobility in n-MOSFETs on (110) Si Sung-Ho Jeon, Noriyuki Taoka , Hiroaki Matsumoto, Kiyotaka Nakano, Susumu Koyama, Hiroshi Kakibayasi, Koji Araki, Moriya Miyashita, Koji Izunome, Mitsuru Takenaka and Shinichi Takagi The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Tel: +81-3-5841-6733, Fax: +81-3-5841-8564, E-mail: takagi@ee.t.u-tokyo.ac.jp Nagoya University, Hitachi High-technologies Corporation, Covalent Silicon Corporation

Quantum Chemical Analysis of Metal Adsorption Mechanism onto Silicon Surface in Cleaning Solution

Fe3+ and Al3+ complex ion structures in aqueous solution were estimated by ab initio molecular orbital theory. The reactivity between the metal complex ions and Si surface depends on the pH of the solution, which was well explained by the frontier orbital theory. Based on the result of theoretical estimation, the addition of a chelating agent to basic solution to prevent the OH- ion from coordinating with metal ions is demonstrated to be effective in suppressing metal adsorption to the silicon surface.

Metal Removal from a Silicon Surface by UV Irradiation in Pure Water

A new wet cleaning method using pure water and ultraviolet light has been investigated. This method, the PWruV cleaning, is simply irradiating a pure water coated silicon wafer with ultraviolet light. The metal removal efficiency was evaluated for transition metals adsorbed on hydrophilic surface and copper deposited on hydrophobic surface. It was found that the PWUV cleaning has high efficiency for metal removal without any reactive chemicals and gases