Semiconductor device and method for preparing semiconductor device

A semiconductor device, comprising:

• a semiconductor substrate, wherein a support layer is formed on the semiconductor substrate, and a trench is formed in the support layer;
• a filling layer, wherein the filling layer fills a portion of the trench, and a thickness a of the filling layer and a depth b of the trench satisfy:
• ⅓b≤a≤½b;
• an adhesion layer formed on a surface of the filling layer and arranged in the trench;
• a first conductive layer formed on a surface of the adhesion layer and a surface of the support layer;
• and
• a second conductive layer formed in the first conductive layer and filling the trench.

A semiconductor device, comprising:

• a semiconductor substrate, wherein a support layer is formed on the semiconductor substrate, and a trench is formed in the support layer;
• a filling layer, wherein the filling layer fills a portion of the trench, and a void is formed in the filling layer;
• and
• a plug formed in the trench and at least partially extending into the void.