Hitachi Plant Engineering & Construction says it has developed a complete, functioning clean room for the fabrication of 64M-bit dynamic memory chips, which will be so fine that even a slight change of room temperature affecting expansion or contraction of silicon wafers and photolithographic machines and photosensitiser could wreck the production run, while changes of air pressure in the room influences the wavelength of the circuit-writing lasers: Hitachi Plant claims its clean room will maintain the environmental conditions necessary for 0.4 micron design rules by allowing no more than one particle of 0.5 micron or larger size per cubic foot; the room temperature will be kept to within plus or minus 0.02oC and the air pressure, selectable between 1030 and 1040 millibars.
