Semiconductor device and manufacture thereof

A semiconductor device manufacturing method, comprising:

• providing a semiconductor structure, comprising:
• an interlayer dielectric layer;
• a first metal layer surrounded by the interlayer dielectric layer;
• and
• a semiconductor layer on the interlayer dielectric layer;
• etching the semiconductor layer to form an opening exposing the interlayer dielectric layer, wherein the opening comprises a first opening and a second opening on the first opening, with the first opening exposing a portion of the interlayer dielectric layer, and the first opening and the second opening forming a staircase pattern;
• forming an insulation layer on the semiconductor structure;
• etching a portion of the insulation layer and a portion of the interlayer dielectric layer at the bottom of the first opening to form a groove exposing a portion of the first metal layer;
• forming a second metal layer on the insulation layer and on the bottom and a side surface of the groove, with the second metal layer contacting the first metal layer;
• and
• patterning the second metal layer to remove a portion of the second metal layer on a side surface of the opening and on the staircase pattern.