Ultra clean technology using UV/photoelectron method for semiconductor transportation and its effect on MOS devices

摘要

Feasibility of a plastic wafer box with a UV/photoelectron cleaning unit (UV unit) for a practical application has been investigated. Chemical contaminant evaluations for the box air and Si wafer surface were carried out with GC/MS. Metal-oxide-semiconductor (MOS) capacitors were fabricated after the storage in various boxes before or after gate oxidation and their reliability tests were carried out. The total ion chromatogram (TIC) spectra showed a dramatical reduction of organic contaminants adsorbed on Si wafers stored in the newly developed poly-ether sulfone (PES) box equipped with the UV unit. We found that the injected charge at which the gate oxide undergoes the final hard breakdown is markedly improved by the installation of the UV unit to the PES box. However, the soft breakdown of gate oxides was so sensitive to the organic contaminants on Si surfaces that it hardly depended on the typesed of used storage boxes. We concluded that the PES/UV unti water box is useful for the practical wafer box.