A first metal layer can be deposited over first dielectric material layers of a first substrate, and can be patterned into first bonding pads. A first low-k material layer can be formed over the first bonding pads. The first low-k material layer includes a low-k dielectric material such as a MOF dielectric material or organosilicate glass. A second semiconductor die including second bonding pads can be provided. The first bonding pads are bonded to the second bonding pads to form a bonded assembly.

A first metal layer can be deposited over first dielectric material layers of a first substrate, and can be patterned into first bonding pads. A first low-k material layer can be formed over the first bonding pads. The first low-k material layer includes a low-k dielectric material such as a MOF dielectric material or organosilicate glass. A second semiconductor die including second bonding pads can be provided. The first bonding pads are bonded to the second bonding pads to form a bonded assembly.

At least one polymer material may be employed to facilitate bonding between the semiconductor dies. Plasma treatment, formation of a blended polymer, or formation of polymer hairs may be employed to enhance bonding. Alternatively, air gaps can be formed by subsequently removing the polymer material to reduce capacitive coupling between adjacent bonding pads.

At least one polymer material may be employed to facilitate bonding between the semiconductor dies. Plasma treatment, formation of a blended polymer, or formation of polymer hairs may be employed to enhance bonding. Alternatively, air gaps can be formed by subsequently removing the polymer material to reduce capacitive coupling between adjacent bonding pads.

At least one polymer material may be employed to facilitate bonding between the semiconductor dies. Plasma treatment, formation of a blended polymer, or formation of polymer hairs may be employed to enhance bonding. Alternatively, air gaps can be formed by subsequently removing the polymer material to reduce capacitive coupling between adjacent bonding pads.

At least one polymer material may be employed to facilitate bonding between the semiconductor dies. Plasma treatment, formation of a blended polymer, or formation of polymer hairs may be employed to enhance bonding. Alternatively, air gaps can be formed by subsequently removing the polymer material to reduce capacitive coupling between adjacent bonding pads.

A method for forming a semiconductor structure includes following operations. A first substrate including a first side, a second side opposite to the first side, and a metallic pad disposed over the first side is received. A dielectric structure including a first trench directly above the metallic pad is formed. A second trench is formed in the dielectric structure and a portion of the first substrate. A sacrificial layer is formed to fill the first trench and the second trench. A third trench is formed directly above the metallic pad. A barrier ring and a bonding structure are formed in the third trench. A bonding layer is disposed to bond the first substrate to a second substrate. A portion of the second side of the first substrate is removed to expose the sacrificial layer. The sacrificial layer is removed by an etchant.

A method for forming a semiconductor structure includes following operations. A first substrate including a first side, a second side opposite to the first side, and a metallic pad disposed over the first side is received. A dielectric structure including a first trench directly above the metallic pad is formed. A second trench is formed in the dielectric structure and a portion of the first substrate. A sacrificial layer is formed to fill the first trench and the second trench. A third trench is formed directly above the metallic pad. A barrier ring and a bonding structure are formed in the third trench. A bonding layer is disposed to bond the first substrate to a second substrate. A portion of the second side of the first substrate is removed to expose the sacrificial layer. The sacrificial layer is removed by an etchant.

A semiconductor structure includes a first substrate, a metallic pad disposed over the first substrate, a dielectric structure disposed over the first substrate and exposing a portion of the metallic pad, a bonding structure disposed over and electrically connected to the metallic pad, a barrier ring surrounding the bonding structure, and a through-hole penetrating the first substrate and the dielectric structure. The bonding structure includes a bottom and a sidewall, the bottom of the bonding structure is in contact with the metallic pad, a first portion of the sidewall of the bonding structure is in contact with the dielectric structure, and a second portion of the sidewall of the bonding structure is in contact with the barrier ring.

A semiconductor structure includes a first substrate, a metallic pad disposed over the first substrate, a dielectric structure disposed over the first substrate and exposing a portion of the metallic pad, a bonding structure disposed over and electrically connected to the metallic pad, a barrier ring surrounding the bonding structure, and a through-hole penetrating the first substrate and the dielectric structure. The bonding structure includes a bottom and a sidewall, the bottom of the bonding structure is in contact with the metallic pad, a first portion of the sidewall of the bonding structure is in contact with the dielectric structure, and a second portion of the sidewall of the bonding structure is in contact with the barrier ring.