| 摘要 |
PURPOSE:To increase operating speeds at low temperatures by a method wherein impurity concentration in a substrate region wherein electric charges transfer channels are formed is so set that the signal loaded electric charges mobility determined by impurities scattering at service temperature is larger than the mobility determined by substrate constituting atoms lattice scattering. CONSTITUTION:A semiconductor substrate 30 is built when an intrinsic semiconductor region 36 is formed on a P type Si substrate 31. Then, the region 36 is coated with an SiO2 dielectric layer 32. Next, several Al or polycrystalline Si transfer electrode 34a-34f are installed on the layer 32 with a prescribed gap between. A first clock pulse is supplied across the electrodes 34a and 34d and then a second across the electrodes 34b and 34c 120 deg. behind the first. a third is supplied across the electrodes 34c and 34f that is another 120 deg. behind the second. The relationship between impurity concentration in the substrate 31CB/cm<3> and the service temperature T must meet a condition: (3.37X10<8>XT<4>)/[ln(1+4.5X 10<8>XT<2>XCB<2/3>)]>CB. |
