Semiconductor structure and fabrication method thereof

A method for fabricating a semiconductor structure, comprising:

• providing a semiconductor substrate, the semiconductor substrate being provided with a plurality of first bit lines extending along a first direction;
• forming a first transistor array on the semiconductor substrate, the first transistor array comprising a plurality of first semiconductor pillars;
• forming first word lines, each of the plurality of first semiconductor pillars being connected to a corresponding one of the first word lines and a corresponding one of the plurality of first bit lines;
• forming a second transistor array on the first transistor array, the second transistor array comprising a plurality of second semiconductor pillars, and the plurality of first semiconductor pillars being corresponding to the plurality of second semiconductor pillars one to one;
• and
• forming second word lines and second bit lines, each of the plurality of second semiconductor pillars being connected to a corresponding one of the second word lines and a corresponding one of the second bit lines.