A three-level metallization three-phase CCD

A new electrode structure for CCD´s is described. This structure is three-phase with three levels of metal and considerably relaxes the demands on the photolithography. It is predicted and shown that this structure leads to devices with a high performance, a high packing density, and a high yield over very large areas. Devices with 256 and 64 elements, primarily intended for analog delay applications, have been fabricated and measured. Transfer inefficiencies of 5 × 10^-5with only 5-percent background charge and a transfer noise corresponding to an interface state density in the low 10⁹cm^-2eV^-1have been measured in a surface channel device. The devices may be satisfactorily operated at pulse voltages of a few volts. In bulk channel devices, transfer ineffciencies of 2.5 × 10^-5have been observed, and bulk state densities of 2 × 10¹¹cm^-3have been derived.