A substrate processing apparatus is provided. A substrate processing apparatus comprises a reaction chamber provided with a chamber wall comprising a first sidewall, a second sidewall disposed opposite to the first sidewall, a bottom wall connected to the first sidewall and the second sidewall; a gate valve tunnel disposed in the first sidewall configured to be closed by a gate valve; a substrate support provided with a top plate and a shaft, the substrate support being disposed within the reaction chamber and configured to support a substrate on the top plate, wherein the substrate support is configured to be vertically movable between a process position and a transfer position; and a liner disposed around perimeter of the substrate support and configured to move with the substrate support, wherein an outer wall of the liner is configured to cover the gate valve tunnel when the substrate support is in the process position.