Capacitor incorporated in semiconductor device having a lower electrode

Abstract

In a capacitor incorporated in a semiconductor device, a capacitor lower plate is formed of a first amorphous silicon film on an interlayer insulator film and a second amorphous silicon film stacked on the first amorphous silicon film. A crystallization preventing film is formed between the first and second amorphous silicon films, or alternatively, the first amorphous silicon film is formed to have an impurity concentration lower than that of the second amorphous silicon film. A stacked structure formed of the first and second amorphous silicon films is patterned into a capacitor lower plate having a top surface and a side surface, and hemispherical grains are formed on not only the top surface but also the side surface of the patterned stacked structure. In this process, crystalline growth from the interlayer insulator film is prevented by the crystallization preventing film or by the fact that the first amorphous silicon film is formed to have an impurity concentration lower than that of the second amorphous silicon film. Thus, concaves and convexes in the form of hemispherical grains are uniformly formed on not only the top surface but also the side surface of the patterned stacked structure, so that a remarkably increased capacitance can be obtained.