Semiconductor device and method for forming the same

A semiconductor device, comprising:

• a first semiconductor chip comprising a first metallization structure on a first substrate;
• a second semiconductor chip bonded to the first semiconductor chip, and the second semiconductor chip comprising a second metallization structure on a second substrate;
• and
• a conductive plug penetrating the first semiconductor chip and extending to the second semiconductor chip for electrically connecting the first metallization structure and the second metallization structure;
• and
• a dielectric structure surrounding a portion of a sidewall of the conductive plug, and the dielectric structure comprising:
• a middle dielectric layer formed between an outer dielectric layer and an inner dielectric layer, wherein a dielectric constant of the outer dielectric layer is greater than a dielectric constant of the middle dielectric layer, and the
• outer dielectric layer has a L-shaped cross section between the conductive plug and the first substrate.

A method for forming a semiconductor device, comprising:

• providing a first semiconductor chip comprising a first metallization structure on a first substrate and a second semiconductor chip comprising a second metallization structure on a second substrate;
• bonding the first metallization structure of the first semiconductor chip to the second metallization structure of the second semiconductor chip;
• forming a first trench extending from a second surface of the first substrate to a predetermined depth in the first substrate;
• forming an isolation lamination along a sidewall and a bottom surface of the first trench, wherein the isolation lamination comprises a middle dielectric layer between an outer dielectric layer and an inner dielectric layer, and the outer dielectric layer has a dielectric constant greater than 3.9 and separates the middle dielectric layer from the first substrate;
• forming a second trench by removing a bottom portion of the isolation lamination in the first trench, wherein the second trench extends to the second metallization structure of the second semiconductor chip;
• and
• forming a conductive plug in the first trench and the second trench.