An injection module assembly (IMA) that moves along a predetermined path to inject gas onto a substrate and discharge excess gas is described. The IMA may be used for processing a substrate that is difficult to move for various reasons such as a large size and weight of the substrate. The IMA is connected to one or more sets of jointed arms with structures to provide one or more paths for injecting the gas or discharging the excess gas. The IMA is moved by a first driving mechanism (e.g., linear motor) and the jointed arms are separately operated by a second driving mechanism (e.g., pulleys and cables) to reduce force or torque caused by the weight of the jointed arms. The movement of the first driving mechanism and the second driving mechanism is synchronized to move the IMA and the jointed arms.