Asahi Kasei Kabushiki Kaisha

Asahi Kasei Kogyo Kabushiki Kaisha

Masahiro Matsui

Takashi Morishita

Makoto Ishida

Shoichiro Tonomura

Yoshitaka Moriyasu

When a SOI substrate is produced a first silicon layer epitaxially grown on the insulating underlay is ion implanted to make deep part of interface of the silicon layer amorphous, and then annealed to recrystallize. Next, the silicon layer is heat treated to oxidize part of the surface side, and after the silicon oxide is removed by etching, a silicon layer is epitaxially grown on the remaining first silicon layer to form a second silicon layer. Subsequently, the second silicon layer is again ion implanted to make deep part of interface amorphous, then annealing is performed to recrystallize. With this method, a SOI substrate, which is very small in crystal defect density of the silicon layer and good in surface flatness, can be produced. Therefore, on the semiconductor substrate an electronic device or optical device having high device performance and reliability can be realized.

Semiconductor substrate and its production method, semiconductor device comprising the same and its production method

When producing an SOS substrate by growing a silicon layer on a sapphire substrate, or when producing an SOI substrate by depositing an oxide layer or a fluoride layer, as an intermediate layer, on a silicon substrate, and growing a silicon layer on the deposited layer, (A) after growth of the silicon layer, heat treatment is performed in an oxidizing atmosphere to oxidize a part of a surface side of the silicon layer, and the resulting silicon oxide layer is removed by etching with hydrofluoric acid. (B) With this silicon layer as a seed layer, a silicon layer is regrown homoepitaxially thereon.

SOI substrate and process for preparing the same, and semiconductor device and process for preparing the same

A high luminance thin-film electroluminescent device comprising a phosphor layer comprising SrS as the host material and a luminous center. The phosphor layer is sandwiched between two insulating layers and two thin-film electrodes are provided on each side of the insulating layers. At least one of the electrodes is transparent, and the excitation spectrum of the phosphor layer exhibits a peak having a maximum value at a wavelength of about from 350 nm to 370 nm. Such a high luminance thin-film electroluminescent device can be prepared by annealing its phosphor layer comprising SrS as the host material at a temperature of at least 650 .degree. C. for at least one hour in an atmosphere of a sulfur-containing gas.

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Shizuoka, Japan

Masahiro Matsui