| 摘要 |
PROBLEM TO BE SOLVED: To prevent a drop of Q value by a resistance to the earth producing in a semiconductor substrate by forming a lower resistance layer than the substrate between the first insulating layer and the substrate in which a first insulation layer, a first conductive layer, a dielectric layer and a second conductive layer are laminated in sequence. SOLUTION: A conductive layer (low resistance layer) 20 which is lower in resistance than a semiconductor substrate 10 is formed between an insulation layer 12 and the semiconductor substrate 10. Thus, a current flows into the conductive layer 20 through the insulation layer 12 from a conductive layer 14, and it hardly flows into the semiconductor substrate 10. An insulation layer made of oxide film or nitride film may be formed between the conductive layer 20 and semiconductor substrate 10. The formation of the conductive layer 20 reduced a resistance to the earth, and the Q value of a MIM capacitor is made large at a port 1. Since the Q value is improved as the resistance to the earth is reduced, the noise index of an amplifier using a MIM capacitor C can be reduced and a ratio of a carrier of an oscillator output to a noise can be improved.
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