Experimental and simulation studies of thermal flow of borophosphosilicate and phosphosilicate glassesA new fabrication process for solid-state imagers based on the borophosphosilicate glass (BPSG) flow has been developed. It was found that wen-designed tapered steps can be obtained even at low temperatures with the use of BPSG, which can be cleaned in a hot NH 4 0H!H 2 0 2 iH 2 0 solution.As a result, a solid-state imager fabricated using the above process is characterized by satisfactory shapes of tapered steps made of intermediate oxide which give complete metal interconnect lines.