The minimal fab concept was designed in order to achieve brand-new semiconductor fab whose investment cost is 1/1,000 less than that of a conventional mega fab. The targets of minimal fab are the device markets with high-variation and low-volume. The minimal fab has three important features; (1) the wafer diameter is a half inch, (2) each process tool size is 294 mm wide × 450 mm deep × 1440 mm high, and (3) no clean room is needed due to the adoption of local clean technology. This paper describes the concept, the local clean technology of minimal equipment, and the fabrication of devices using the equipment.
In recent years, reduction of initial and running costs of industrial cleanroom is becoming more important because of the price competition of the products. There are previous reports on the cleanroom in which local clean environment near the production area was achieved while simplifying building finish and facilities system as a technique which is not possible by the conventional concept. This paper is the outline of comparison of CFD and experiment between conventional and ceilingless cleanroom in the non-unidirectional airflow cleanroom. Furthermore, we added a system which can change air flow volume according to the particle concentration, and evaluated the effectiveness in energy-saving by the experiments. As a result, we confirmed that the cleanliness of the ceilingless Cleanroom II was comparable to the conventional system, and that it is possible to reduce air flow volume of FFU while keeping the same cleanliness.
In pharmaceutical or food production facilities, a high standard of internal environment of the facility is required, including countermeasures against microorganisms. These countermeasures from the facility point of view include partitioning of work zones (zoning), and cleaning the air using HEPA filters. However, when workers/researchers are working within a facility, dispersion of dust or adhering microbe brought in with clothes, etc., cause pollution of the air. In this report, the sterilization performance of weak acid hypochlorous solution used as the chemical substance was verified. In addition, the sterilization performance in an actual space varied not only with the chemical substance used, but also with the condition of the room, the air conditioning system, the method of spraying, etc. Therefore, from the above sterilization performance tests using chemical substances, the raw data required for a computational fluid mechanics (CFD) model were derived. A method which is capable of predicting the effect of the chemical substance t under various conditions was investigated, and the results are reported.
A plant factory is a facility that precisely controls the internal environment to allow year-round and systematic culture of plants, such as vegetables. Plant factories are now said to be in the third boom. Along with increasing awareness among consumers, vegetables produced in plant factories are catching on in the market. The closed plant factory with artificial lighting is a closed system with high cleanliness, which enables highly controlled cultivation environment, suitable for the production of high value-added plants. This article focuses on the closed plant factory with artificial lighting and introduces the culture environment for plants and the outline of the control and cleaning technologies.
In rural areas of northern China, local household combustion system so-called “Kang” is widely used for heating and cooking with coal, firewood and agricultural waste biomass during the winter season. It is one of the largest pollution sources of fine particles which influence the regional atmosphere and human health. In this study, field measurements were conducted to determine the characteristics of carbonaceous particles including anhydrosugars emitted from Kang combustion of agricultural wasted biomass fuels such as rice straw, corncob, maize stem and gaoliang in rural area in Daton, China. PM2.5 were collected using a personal PM2.5 sampler. Then, we determined the organic carbon (OC), elemental carbon (EC) and anhydrosugars such as levoglucosan (L), mannosan (M), galactosan (G) as the biomass burning tracers in PM2.5. Exhausted carbonaceous particles from Kang combustion of agricultural waste biomass were mostly OC fractions, which may be affected by combustion conditions (smoldering or flame burning), combustion temperature and moisture content when dry or wet waste biomass samples were burnt. It was found that the composition ratios of G/L and (M+G)/L from the combustion of different dry waste biomass samples are obviously higher than those of wild fire and shrubland reported in the literatures.
Composite particles of superparamagnetic nanoparticles coated with silica and chelate resin, we call superparamagnetic chelate resin (SPMCR) particles, were synthesized by a combined method of aerosol and liquid process for removing metal ions from wastewater by adsorption. First, Fe3O4 nanoparticles were prepared by a co-precipitation method and were embedded in silica particles by an alkaline hydrolysis of tetraethylorthosilicate. The Fe3O4 nanoparticles embedded in silica particles (Fe3O4@SiO2 nanoparticles) showed a magnetic property similar to superparamagnetic and were hardly dissolved in 2M HCl aqueous solution. Then the SPMCR particles were prepared by spraying the suspension of Fe3O4@SiO2 nanoparticles and chelate resin particles. The resultant particles by this method were the mixture of SPMCR particles and Fe3O4@SiO2 nanoparticles. They adsorbed 0.89 mmol g-1 of Cu2+ but 0.61 mmol g-1 was recovered by the desorption with water. Both the adsorbed and the desorbed masses of Cu2+ were reduced by 22~25 % after five repetitions of adsorption and desorption.