Semiconductor device and manufacturing method thereof

A method comprising:

• forming a transistor over a substrate;
• depositing a first dielectric layer over a backside of the substrate;
• forming a backside via in the first dielectric layer and the substrate such that the backside via is electrically connected to the transistor;
• forming a second dielectric layer to cover the first dielectric layer but expose the backside via, comprising:
• forming a blocking layer to cover a backside surface of the backside via, wherein the blocking layer is spaced apart from the first dielectric layer;
• depositing the second dielectric layer to cover the first dielectric layer but not the blocking layer;
• and
• after depositing the second dielectric layer, removing the blocking layer;
• depositing a third dielectric layer to cover the second dielectric layer and in contact with the backside via;
• and
• forming a backside conductive line in the third dielectric layer and the second dielectric layer to be electrically connected to the backside via.

A method comprising:

• forming a transistor over a front-side of a substrate;
• thinning the substrate from a backside of the substrate;
• after thinning the substrate, depositing an etch stop layer on the backside of the substrate;
• forming a backside via in the etch stop layer and the substrate and in contact with the transistor;
• forming a blocking layer to cover a backside surface of the backside via, wherein the blocking layer is spaced apart from the etch stop layer;
• depositing a high-k dielectric layer to cover the etch stop layer but not the blocking layer;
• after depositing the high-k dielectric layer, removing the blocking layer;
• and
• forming a backside conductive line to be in contact with the backside via and partially surrounded by the high-k dielectric layer.