Abstract: A reactive ion etching apparatus includes first and second reactive chambers in a single buffer room. First and second stages are placed in front of corresponding reactive chambers. The centers of the reactive chambers and stages form a square. A first transfer arm transfers a wafer between the first reactive chamber and the first stage, a second transfer arm transfers the wafer among the first and second reactive chambers and the first and second stages, and a third transfer arm transfers the wafer between the second reactive chamber and the second stage. The second transfer arm is pivotably mounted at the center of the square and may turn a full 360.degree..