A three-level metallization three-phase CCD

Abstract

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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> with only 5-percent background charge and a transfer noise corresponding to an interface state density in the low 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> eV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> have 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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> have been observed, and bulk state densities of 2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> have been derived.