| 摘要 |
PURPOSE:To reduce the scattering of a CR value in a CR time constant circuit by providing the CR time constant circuit constituted by a resistor R formed by polycrystalline silicon and a capacitance C formed by polycrystalline silicon, an oxide film and a metallic electrode. CONSTITUTION:An oxide film 10 is shaped on a semiconductor substrate 1, and a polycrystalline silicon layer 20 in thickness H is deposited. The polycrystalline silicon 20 is patterned. An impurity is doped to a section as one electrode of a capacitance and a contact section in a resistor through polycrystalline silicon ion implantation, etc. to form polycrystalline silicon 21 having low resistance. Polycrystalline silicon is oxidized in order to form a protective film consisting of polycrystalline silicon and an oxide film as a dielectric for the capacitance to shape oxide films 30 in thickness d. The thickness H' of polycrystalline silicon is brought to approximately H'=H-d/2 at that time. The oxide films are removed selectively in order to make contacts, and metallic electrodes 40 are formed, thus completing the semiconductor device. |
