| 摘要 |
PURPOSE:To reduce the voltage dependency of a capacitor by constituting the lower electrode of the capacitor in impurity concentration higher than source and drain regions. CONSTITUTION:A field SiO2 film 2 is formed to one main surface of a P type Si substrate 1, a gate oxide film 3 is formed, and the gate electrode 5 of a MISFET by a poly Si film and the lower electrode 6 of the capacitor are formed to the whole surface. Ion beams 7 of an N type impurify are irradiated to the whole surface. Consequently, the N<+> type source region 8 and drain region 9 are formed on both sides in a self-alignment manner as using the electrode 5 as a mask while the resistance of the film 6 is reduced. A section on a MISFET section is coated selectively with a photo-resist, the ion beams of the N type impurity are irradiated while using the photoresist as a mask, and the quantity of the impurity introduced into the film 6 is increased. As a result, the film 6 is changed into N<++> type, and displays sufficiently low resistance value as the lower electrode of the capacitor. A SiO2 film 12 as a dielectric film is grown on the exposed surface of the film 6. Accordingly, a depletion layer is made difficult to extend in the film 6 on operation as the capacitor. |
