A semiconductor device includes a program word line and a read word line over an active region. Each of the program word line and the read word line extends along a line direction. Moreover, the program word line engages a first transistor channel and the read word line engages a second transistor channel. The semiconductor device also includes a first metal line over and electrically connected to the program word line and a second metal line over and electrically connected to the read word line. The semiconductor device further includes a bit line over and electrically connected to the first active region. Additionally, the program word line has a first width along a channel direction perpendicular to the line direction; the read word line has a second width along the channel direction; and the first width is less than the second width.