Patent ID: 6430079
Filing Date: 2002-08-06
Classification: G11C,H01L

Abstract:
A flat memory cell read only memory comprising a plurality of sub-arrays; each sub-array comprising:a plurality of first buried diffusion regions planted into the substrate; part of the first buried diffusion region in the substrate being formed with even diffusion lines and odd diffusion lines; a plurality of conductive bitlines covering on the insulating layer and being electrically connected to the diffusion regions through a plurality of contact windows; a plurality of word lines covering on the insulating layer, and cutting out the first buried diffusion region; a plurality of memory cells installed between different first buried diffusion regions and below the word lines for forming a memory cell array; a plurality of second buried diffusion regions being in the substrate so that the second buried diffusion regions space respective odd diffusion lines; the second, buried diffusion region being connected to the conductive bitlines through a plurality of contact windows; a first memory cell selecting line pair covering on the insulating layer; the first memory cell selecting line pair cutting the even diffusion lines and the second buried diffusion regions so as to be formed with a memory cell selecting transistor between two adjacent even diffusion lines and adjacent second buried diffusion regions and a section below one of the first memory cell selecting pairs; a plurality of third buried diffusion regions being in the substrate so that the third buried diffusion regions space the respective even diffusion lines; and the third buried diffusion regions are connected to the conductive bitlines through a further plurality of contact windows; and a second memory cell selecting line pair covering on the insulating layer; the second memory cell selecting line pair cutting the odd diffusion lines and third buried diffusion regions so as to be formed with a memory cell selecting transistor between two adjacent odd diffusion lines and adjacent second buried diffusion regions and a section below one of the second memory cell selecting pairs.