Method of maintaining cleanliness of substrates and box for accommodating substrates

Abstract

A method of maintaining cleanliness of substrates including a first step for accommodating at least a piece of substrate having a gaseous impurity-trapping filter arranged close thereto in a hermetically sealed box, and a second step for circulating the atmosphere in the box at a rate of two or more times a minute so that impurities in the atmosphere are adsorbed by the gaseous impurity-trapping filter. A box for accommodating substrates includes a housing in which space for accommodating the substrates is hermetically closed with a lid, a gaseous impurity-trapping filter arranged in the housing and adapted to adsorb impurities contained in the atmosphere in space, and an atmosphere-circulating device having a ratio of the circulating capacity to the space volume of not smaller than 2 in order to circulate the atmosphere so as to pass it through the gaseous impurity-trapping filter.

Dependencies are inferred from the claim text.