Reactive oxygen beam generation system using pulsed laser evaporation of highly concentrated solid ozone

Abstract

A reactive oxygen beam generation system is described for the formation of high-quality and high-precision films. This system utilizes pulsed laser evaporation of highly concentrated solidified ozone (O3). The equipment for safely generating and handling a large amount of high-purity liquid and solid O3 was also developed for this purpose. The beam is characterized by its high concentration of oxygen atoms in an excited state [O(1D)], constant flux per laser shot (4×1017 molecules cm−2 shot−1), appropriate level of kinetic energy (KE) for enhancing the surface reaction (mean KE of 0.4 eV, maximum KE of 2 eV) and small angular spread (6°). These characteristics enabled us to precisely control the SiO2 film thickness by the number of laser shots, and achieve an enhanced Si oxidation rate and new local oxidation process.

High-quality SiO2 film formation by highly concentrated ozone gas at below 600 °C

“…However, oxidation by these sources has the following problems: ͑1͒ Energetically reactive ionic species may impair the grown film; ͑2͒ the number of radicals supplied to the Si surface is limited by the microwave power or light intensity of the apparatus; ͑3͒ nondestructive transportation of the generated radicals to the Si surface is difficult because of their short life resulting from mutual chemical reactivity (O ϩO→O 2 ). To overcome these problems, oxidation by highly concentrated ozone (O 3 ) gas under reduced pressure in cold-wall processing is considered to be promising for the following reasons: ͑1͒ The O 3 molecules have a long life as long as they are kept in a temperature-͑Ͻ100°C͒ and pressure-͑Ͻ44 000 Pa͒ controlled atmosphere, 7 thus enabling the effective transportation of O 3 to the surface; ͑2͒ O 3 can also be used as an in situ oxygen radical source by way of the O 3 decomposition reaction at the surface ͑i.e., O 3 →O 2 ϩO), 8 indicating that the number of supplied radicals can be increased by increasing the O 3 pressure at the surface; ͑3͒ the O 3 -formed SiO 2 film has been confirmed to have a more homogeneous structure with less Si displacement and a thin-ner transition layer at the SiO 2 /Si interface than thermally grown oxide 9,10 which would result in better electrical properties for the thin SiO 2 layer as a gate dielectric film.…”

“…Details of the operation of this generator have been described elsewhere. 7 To prevent a decrease in the concentration of O 3 gas during its flow to the Si surface, we applied lamp-heated cold-wall processing for oxidation. The results of our previous experiment suggested that, in ideal conditions that limit the heated area ͑Ͼ30°C͒ to just around the Si surface, the concentration of O 3 gas arriving at the Si surface was more than 93%.…”

Nanoscale-order Homogeneous Structure of SiO2 Film on Poly-silicon Grown at Room Temperature using UV Light Excited Ozone.

“…The ~100% O 3 was supplied using a pure ozone generator (Type: MPOG-SM1C1, Meidensha corp., Japan). The principles of the production method of the 100% ozone and the details of the pure ozone generator are described elsewhere [9][10][11][12]. The detail of the experimental setup is also described in a previous paper [5].…”

Advantage of Highly Concentrated (≥90%) Ozone for Chemical Vapor Deposition SiO2 Grown under 200 °C Using Hexamethyldisilazane and Ultraviolet Light Excited Ozone

“…We estimated that the concentration of the HC ozone at the oxidation chamber was still above 90 vol % by thermal desorption spectroscopy (TDS) measurement at low temperatures. 7) Thus, the ozone gas concentration throughout the process is above 90 vol %. The sample was placed on the quartz susceptor for heating to 300 C by irradiation using the infrared lamp.…”