Embodiments of bonded semiconductor structures and fabrication methods thereof are disclosed. In an example, a method for forming a semiconductor device is disclosed. A first device layer is formed above a first substrate. A first bonding layer including a first bonding contact is formed above the first device layer. The first bonding contact is made of a first indiffusible conductive material. A second device layer is formed above a second substrate. A second bonding layer including a second bonding contact is formed above the second device layer. The first substrate and the second substrate are bonded in a face-to-face manner, such that the first bonding contact is in contact with the second bonding contact at a bonding interface.

A semiconductor device includes a semiconductor substrate, a dielectric structure, an electrical insulating and thermal conductive layer and a circuit layer. The electrical insulating and thermal conductive layer is disposed over the semiconductor substrate. The dielectric structure is disposed over the electrical insulating and thermal conductive layer, wherein a thermal conductivity of the electrical insulating and thermal conductive layer is substantially greater than a thermal conductivity of the dielectric structure. The circuit layer is disposed in the dielectric structure.

A semiconductor device includes a semiconductor substrate, a dielectric structure, an electrical insulating and thermal conductive layer and a circuit layer. The electrical insulating and thermal conductive layer is disposed over the semiconductor substrate. The dielectric structure is disposed over the electrical insulating and thermal conductive layer, wherein a thermal conductivity of the electrical insulating and thermal conductive layer is substantially greater than a thermal conductivity of the dielectric structure. The circuit layer is disposed in the dielectric structure.

An SiC semiconductor device includes an SiC chip having a first main surface at one side and a second main surface at another side, a first main surface electrode including a first Al layer and formed on the first main surface, a pad electrode formed on the first main surface electrode and to be connected to a lead wire, and a second main surface electrode including a second Al layer and formed on the second main surface.

An SiC semiconductor device includes an SiC chip having a first main surface at one side and a second main surface at another side, a first main surface electrode including a first Al layer and formed on the first main surface, a pad electrode formed on the first main surface electrode and to be connected to a lead wire, and a second main surface electrode including a second Al layer and formed on the second main surface.

A semiconductor structure includes a first device and a second device bonded on the first device. The first device has a first sidewall distal to the second device and a second sidewall proximal to the second device. A surface roughness of the second sidewall is larger than a surface roughness of the first sidewall.

A semiconductor structure includes a first device and a second device bonded on the first device. The first device has a first sidewall distal to the second device and a second sidewall proximal to the second device. A surface roughness of the second sidewall is larger than a surface roughness of the first sidewall.

A bonded assembly of a first semiconductor die and a second semiconductor die includes first and second semiconductor dies. The first semiconductor die includes first semiconductor devices, first metal interconnect structures embedded in first dielectric material layers, and first metal bonding pads laterally surrounded by a semiconductor material layer. The second semiconductor die includes second semiconductor devices, second metal interconnect structures embedded in second dielectric material layers, and second metal bonding pads that include primary metal bonding pads and auxiliary metal bonding pads. The auxiliary metal bonding pads are bonded to the semiconductor material layer through metal-semiconductor compound portions formed by reaction of surface portions of the semiconductor material layer and an auxiliary metal bonding pad. The primary metal bonding pads are bonded to the first metal bonding pads by metal-to-metal bonding.

A semiconductor device includes a semiconductor substrate, a dielectric structure, an electrical insulating and thermal conductive layer and a circuit layer. The electrical insulating and thermal conductive layer is disposed over the semiconductor substrate. The dielectric structure is disposed over the electrical insulating and thermal conductive layer, wherein a thermal conductivity of the electrical insulating and thermal conductive layer is substantially greater than a thermal conductivity of the dielectric structure. The circuit layer is disposed in the dielectric structure.

A semiconductor device includes a semiconductor substrate, a dielectric structure, an electrical insulating and thermal conductive layer and a circuit layer. The electrical insulating and thermal conductive layer is disposed over the semiconductor substrate. The dielectric structure is disposed over the electrical insulating and thermal conductive layer, wherein a thermal conductivity of the electrical insulating and thermal conductive layer is substantially greater than a thermal conductivity of the dielectric structure. The circuit layer is disposed in the dielectric structure.