Patent ID: 6689660
Filing Date: 2004-02-10
Classification: H01L

Abstract:
A method for producing a memory array including a plurality of memory cells on a semiconductor substrate, comprising:providing a semiconductor substrate; forming a plurality of layers of semiconducting material on a surface of the substrate, including a first layer of a material of a first conductivity type formed on the substrate, a second layer of a material of a second conductivity type formed on the first layer, and a third layer of a material of the first conductivity type formed on the second layer; forming a plurality of first trenches in the layers of semiconducting material to form a plurality of bars having the first, second and third layers of semiconducting material, the first layer of semiconducting material of each of the bars functioning as a bit line for the memory array; forming a plurality of second trenches in the layers of semiconducting material in a direction that is orthogonal to the direction of the bit lines to define a plurality of in-line access transistors on each of the bit lines, each of the access transistors having a vertical channel region, defined by the second layer of material, exposed in a sidewall of one of the second trenches; forming a gate oxide on the sidewall of the second trenches, overlying the channel regions of alternate ones of the access transistors on first alternate ones of the bit lines and overlying the channel regions of alternate ones of the access transistors on second alternative ones of the bit lines; forming first and second word lines in each of the second trenches, with the first word line extending in the proximity of the channel regions of the access transistors on the first alternate ones of the bit lines, and with the second word line extending in the proximity of the channel regions of the access transistors on the second alternate ones of the bit lines; and filling the second trenches with a dielectric material to bury the first and second word lines in the dielectric material in the second trenches.