Semiconductor device with composite dielectric structure and method for forming the same

1. A semiconductor device, comprising:

an interconnect structure disposed over a first semiconductor die, wherein the first semiconductor die comprises a semiconductor substrate and a first conductive pad disposed over the semiconductor substrate, and the first conductive pad is covered by the interconnect structure; dielectric spacers surrounding the interconnect structure, wherein an interface between the dielectric spacers and the interconnect structure is curved;

a dielectric layer surrounding the dielectric spacers;

a second semiconductor die bonded to the dielectric layer and the interconnect structure, wherein the second semiconductor die comprises a second conductive pad, and the interconnect structure is covered by the second conductive pad; and

a dielectric lining layer disposed between the first semiconductor die and the dielectric layer, wherein the dielectric lining layer is partially covered by the dielectric spacers;

wherein the interconnect structure is in direct contact with the dielectric lining layer and the first conductive pad.

2. The semiconductor device of claim 1 , wherein the dielectric spacers and the dielectric layer are made of different materials.

3. The semiconductor device of claim 1 , wherein a top width of the interconnect structure is greater than a bottom width of the interconnect structure.

4. The semiconductor device of claim 1 , further comprising:

a dielectric structure penetrating through the dielectric layer, wherein a material of the dielectric structure is the same as a material of the dielectric spacers.

5. The semiconductor device of claim 1 , wherein the dielectric spacers and the dielectric lining layer are made of different materials.

6. A semiconductor device, comprising:

a first dielectric layer disposed over a first semiconductor substrate;

a first conductive pad embedded in the first dielectric layer;

a dielectric lining layer disposed over the first dielectric layer;

a second dielectric layer disposed over the dielectric lining layer;

an interconnect structure penetrating through the second dielectric layer and the dielectric lining layer;

a dielectric spacer disposed between the interconnect structure and the second dielectric layer; and

a second semiconductor substrate disposed over the second dielectric layer, wherein a second conductive pad in the second semiconductor substrate is electrically connected to the first conductive pad through the interconnect structures;

a dielectric structure disposed in the second dielectric layer and separated from the dielectric spacer, wherein the dielectric structure and the dielectric spacer are disposed over the dielectric lining layer;

wherein a material of the dielectric structure is the same as a material of the dielectric spacer, and a width of the dielectric structure is greater than a bottom width of the dielectric spacer.

7. The semiconductor device of claim 6 , wherein the interconnect structure has curved sidewalls, and a top width of the interconnect structure is greater than a bottom width of the interconnect structure.

8. The semiconductor device of claim 6 , wherein the dielectric lining layer and the second dielectric layer are made of different materials.

9. The semiconductor device of claim 6 , wherein the interconnect structure further comprises:

a conductive structure; and

a conductive liner surrounding the conductive structure, wherein the conductive structure is separated from the first conductive pad and the dielectric spacer by the conductive liner.