| 摘要 |
A variable-capacitance device has an n-type diffusion layer which has an impurity concentration profile such that a region where the impurity concentration remains substantially constant and a region where the impurity concentration changes abruptly are alternately repeated, and the impurity concentration increases as the deepness from the surface increases. The impurity concentration profile can be achieved by implanting n-type impurity atoms a plurality of times with different energies in an ion implantation process or varying the concentration of n-type impurity atoms such as of phosphorus added upon epitaxial layer growth. The variable-capacitance device, and a semiconductor integrated circuit device composed of a plurality of such variable-capacitance devices can be fabricated on a semiconductor substrate, and are highly stable.
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