Requirements for contamination control in the G-bit era

In future G-bit DRAM fabrication, the particle density on wafers will be seriously increased. This is because the deposition velocity of particles smaller than 0.1μm drastically increases, and is further accelerated by the electrostatic potential of wafers. The lower limit of the conventional cleanroom cleanliness will be class 0.1-1 level, by dust generation from people. This fact leads us to the minienvironment fab system with automated I/O. In minienvironment systems, however, organic contamination will be a serious problem. Box material, plasticizer and anti-oxidizing agent must be reexamined from the viewpoint of organic contamination control