Kohei Watanuki

Dependence of the Decomposition of Trimethylaluminum on Oxygen Concentration

Trimethylaluminum (TMA) is often used as a source gas for composite semiconductor or gate insulator films containing aluminum. However, TMA readily reacts with O 2 and this reaction causes film performance to degrade. Film formation is affected by the decomposition properties of the source gas, so it is important to investigate the influence of O 2 on the decomposition behavior of TMA. The starting decomposition temperature of TMA was 332°C in an Al 2 O 3 tube filled with Ar gas, and the decomposition rate increased rapidly above 380°C. However, when TMA was heated in an atmosphere containing more than 1 ppm O 2 , the temperature at which TMA began to decompose increased. It is assumed that this phenomenon resulted from the formation of methoxy groups through reaction between TMA and O 2 . Thus, the presence of O 2 in TMA not only caused the films to be contaminated with oxygen atoms but also altered the decomposition behavior of TMA. This means that fluctuations in the deposition rate and film performance are caused by the presence of O 2 in TMA when deposition conditions are otherwise kept constant. As a result, it is desirable that the O 2 concentration present in TMA is maintained below 0.1 ppm during deposition.

Characterization of Zinc Oxide Films Grown by a Newly Developed Plasma Enhanced Metal Organic Chemical Vapor Deposition Employing Microwave Excited High Density Plasma

The radical reaction based semiconductor manufacturing has been applied to silicon device process. Such as SiO2 and Si3N4 can be formed at low temperatures of under 500–600 °C. In this study, we applied radical reaction based semiconductor manufacturing to compound semiconductor of ZnO. The characteristics of ZnO films grown by a newly developed plasma enhanced metal organic chemical vapor deposition (MOCVD) employing microwave excited high-density plasma are good. The film formed on a-plane sapphire is epitaxially oriented in c-axis direction, and the composition is similar to ZnO substrate grown by hydrothermal method. The mobility of grown film at around 400 °C is 23 cm2/(Vs), and it is increased to 46 cm2/(Vs) by 700 °C annealing. The carbon concentration in the films can be reduced by the selection of a zinc precursor and the optimization of process conditions. The active species of plasma are effective for the crystallization of films.

Evaluation of Narrow Gap Filling Ability in Shallow Trench Isolation by Organosiloxane Sol-Gel Precursor

Kohei Watanuki, Atsutoshi Inokuchi, Akinori Banba, Nobuyuki Manabe, Hirokazu Suzuki, Tadashi Koike, Tatsuhiko Adachi, Tetsuya Goto, Akinobu Teramoto, Yasuyuki Shirai, Shigetoshi Sugawa and Tadahiro Ohmi 1 New Industry Creation Hatchery Center, Tohoku University, Aza-Aoba 6-6-10, Aramaki, Aobaku, Sendai 980-8579, Japan 2 Ube-nittou kasei co., ltd., 2-1-1 Yabutanishi Gifu 5008386 Japan 3 Graduate School of Engineering, Tohoku University, Aza-Aoba 6-6-11, Aramaki, Aobaku, Sendai 980-8579, Japan 4 WPI Research Center Aza-Aoba 6-6-10, Aramaki, Aobaku, Sendai 980-8579, Japan

Effects of Ion-Bombardment-Assist and High Temperature on Growth of Zinc Oxide Films by Microwave Excited High Density Plasma Enhanced Metal Organic Chemical Vapor Deposition

In this paper we describe the growth of zinc oxide (ZnO) films on a-plane sapphire substrates by plasma enhanced metal organic chemical vapor deposition (PE-MOCVD) employing microwave excited high-density plasma. In detail, we discuss the effects of ion-bombardment-assist and high temperature on structural properties, electrical properties, optical properties, impurity concentration and thermostability by X-ray diffraction (XRD), field emission scanning electron microscopy, Hall effect measurement at room temperature, photoluminescence, secondary ion mass spectrometry and thermal desorption spectroscopy. Ion-bombardment energy is controlled by the condition of radio-frequency (RF) self bias. Moderate ion-bombardment enhances crystallinity, mobility and thermostability, and reduces concentrations of carbon and hydrogen in the films. By raising the growth temperature up to 550 °C, the qualities of films are improved. High quality ZnO film was successfully grown at 550 °C, which is a relatively low temperature compared to general MOCVD. Its full width at half maximum (FWHM) of XRD (0002) rocking curve, carrier concentration and mobility are 0.12°, 5×1016/cm3, and 89 cm2/(Vs), respectively.

Electrical Properties of Metal-Oxide-Containing SiO2 Films Formed by Organosiloxane Sol–Gel Precursor

High-quality SiO2 film formation is important for many applications, such as large-scale integration (LSI) circuit and micro-electro-mechanical system (MEMS) industries. We evaluated the structural and electrical insulation properties of SiO2 films using an organosiloxane-based silica sol–gel precursor derived from a mixture of tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) by changing the molar ratio of TEOS/MTMS. This sol–gel precursor was converted not only to a low-dielectric-constant film with a relative dielectric constant of 2.8 but also to a dense SiO2 film by optimizing baking conditions. The dense SiO2 film from this sol–gel precursor has excellent dielectric characteristics of low leakage current density and high breakdown voltage, whose values are comparable to those of thermal oxide SiO2 films. Furthermore, the breakdown field intensity of these films was improved by adding a small amount of metal oxides, such as TiO2, HfO2, and ZrO2. A maximum breakdown field intensity of 15 MV/cm can be achieved in the case of 10% TiO2 addition.

Effects of Ion-Bombardment-Assist and High Temperature on Growth of Zinc Oxide Films by Microwave Excited High Density Plasma Enhanced MOCVD

Zinc Oxide Films by Microwave Excited High Density Plasma Enhanced MOCVD Hirokazu Asahara, Atsutoshi Inokuchi, Kohei Watanuki, Masaki Hirayama, Akinobu Teramoto, and Tadahiro Ohmi New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aza Aoba, Aramaki, Aoba-ku, Sendai, 980-8579, Japan Phone: +81-22-795-3977, Fax: +81-22-795-3986, E-mail: asahara@fff.niche.tohoku.ac.jp ROHM Co., Ltd., 21, Saiin Mizosaki-cho, Ukyo-ku, Kyoto 615-8585, Japan Tokyo Electron, Ltd., Mitsusawa 650, Hosaka, Nirasaki, Yamanashi 407-0192, Japan Ube Industries, Ltd., 1978-10, Kogushi, Ube, Yamaguchi 755-8633, Japan