A process and apparatus is disclosed for providing access to the interior of a vacuum deposition chamber in a vacuum deposition apparatus without exposing residues, such as chlorosilane residues, within the chamber to moisture and/or oxygen-containing gases. The process comprises first placing over the upper surface of the vacuum deposition apparatus an enclosure which has a bottom opening large enough to completely cover the top opening to the chamber, and which is capable of being filled with one or more non-reactive gases. One or more non-reactive gases are then flowed into the enclosure to purge moisture and/or oxygen-containing gases from the enclosure. After the enclosure has been mounted on the apparatus and purged by the flow of non-reactive gases therein, the vacuum deposition chamber may be opened, while continuing the flow of non-reactive gases into the enclosure. After servicing, the vacuum deposition chamber may be resealed, the flow of non-reactive gases shut off, and the enclosure then removed from the apparatus. In a preferred embodiment, the flow of non-reactive gases into the enclosure is positioned to flow down from the top of the enclosure at a right angle to openings in the sidewall of the enclosure provided for accessing the vacuum deposition chamber, to thereby provide a gas curtain of non-reactive gas flow across the openings to inhibit ingress of moisture and/or oxygen-containing gases, as well as particulate impurities, into the enclosure.