Low-pressure process apparatus

A low-pressure process apparatus comprises a base, a stage, a housing and at least one first roller unit. The stage is disposed on the base for supporting a substrate. The housing is detachably disposed on the base and moves between a first position and a second position. When the housing is in the first position, a chamber is formed between the housing and the base. The stage is disposed in the chamber. When the housing is detached, the first roller unit contacts and supports the housing to facilitate the housing slid toward a first horizontal direction.