An apparatus and method for testing a plurality of electrical components that are coupled to one another. A message sender is requested to create a message ID which is used to identify a message being sent by the message sender. Hence an operation on the display screen and that on the small screen can be executed as the operations corresponding with each other. Moreover, the gate electrode metal layer can include a first material and the gate electrode barrier layer can include a second material, and the first material can have a lower electrical resistivity than the second material. Densification compresses the macro-cavities.