a substrate, having a plurality of word line trenches and source/drain regions each adjacent to each word line trench; and

a plurality of word lines, each located in each word line trench and each comprising a first conductive layer, a single junction layer and a second conductive layer stacked in sequence, wherein, the first conductive layer is located at a bottom of the word line trench; a projection of the word line on a sidewall of the word line trench and a projection of a source/drain region on the sidewall of the word line trench have an overlapping region with a preset height; and in the case that a voltage applied to the word line is less than a preset voltage, a resistance of the single junction layer is greater than the preset resistance, to make the first conductive layer and the second conductive layer disconnected.