Heterogeneous dielectric bonding scheme

1. A method comprising:

putting a first package component into contact with a second package component, wherein:

the first package component comprises a first dielectric layer comprising a first dielectric material, wherein the first dielectric material is a silicon-oxide-based dielectric material;

the second package component comprises a second dielectric layer comprising a second dielectric material different from the first dielectric material, wherein the second dielectric material comprises silicon and an element selected from the group consisting of carbon, nitrogen, and combinations thereof, and wherein before the first package component is put to contact with the second package component, no treatment process using nitrogen (N 2 ) is preformed, and no treatment process using oxygen (O 2 ) is performed; and

performing an annealing process to bond the first dielectric layer to the second dielectric layer.

2. The method of claim 1 , wherein the first dielectric layer has a first oxygen atomic percentage, and the second dielectric layer has a second oxygen atomic percentage, and a first difference between the first oxygen atomic percentage and the second oxygen atomic percentage is greater than about 10 percent.

3. The method of claim 1 , wherein the first dielectric layer comprises a material selected from the group consisting of silicon oxide (SiO 2 ), Fluoro Silicate glass (FSG), undoped silicate glass (USG), Phospho Silicate Glass (PSG), Boro Silicate glass (BSG), and Boro Phospho Silicate Glass (BPSG).

4. The method of claim 1 , wherein the first package component is bonded to the second package component through fusion bonding.

5. The method of claim 1 , wherein the first package component is bonded to the second package component through hybrid bonding, with the first dielectric layer being bonded to the second dielectric layer through fusion bonding, and a first metal pad in the first dielectric layer being bonded to a second metal pad in the second dielectric layer through metal-to-metal direct bonding.

6. The method of claim 5 , wherein before the first package component is put into contact with the second package component, the second package component has a third dielectric material same as the first dielectric material, and the method further comprises replacing the third dielectric material with the second dielectric material.

7. The method of claim 1 , wherein the first package component and the second package component are bonded to each other through wafer-to-wafer bonding.

8. The method of claim 1 , wherein the first package component and the second package component are bonded to each other through die-to-wafer bonding.

9. A package comprising:

a first package component comprising:

a first dielectric layer comprising a first dielectric material, wherein the first dielectric material is a silicon-oxide-based dielectric material; and

a second package component comprising:

a second dielectric layer comprising a second dielectric material different from the first dielectric material, wherein the second dielectric material comprises silicon and an element selected from the group consisting carbon, nitrogen, and combinations thereof, and wherein the first dielectric layer is bonded to the second dielectric layer, wherein the first dielectric layer and the second dielectric layer form a bonding interface layer, and wherein the bonding interface layer has a thickness smaller than 100 Å.

10. The package of claim 9 , wherein the bonding interface layer has the thickness smaller than about 60 Å.

11. The package of claim 9 , wherein the second package component further comprises:

a third dielectric layer overlying and contacting the second dielectric layer, wherein the third dielectric layer comprises a third dielectric material different from the second dielectric material; and

a bond pad in the second dielectric layer and the third dielectric layer.

12. The package of claim 9 , wherein the first dielectric layer has a first oxygen atomic percentage, and the second dielectric layer has a second oxygen atomic percentage, and a first difference between the first oxygen atomic percentage and the second oxygen atomic percentage is greater than about 10 percent.

13. A package comprising:

a first die comprising:

a first semiconductor substrate;

a first integrated circuit at a surface of the first semiconductor substrate; and

a first dielectric layer over the first integrated circuit, wherein the first dielectric layer comprises a first dielectric material; and

a second die bonding to the first die, wherein the second die comprises:

a second semiconductor substrate;

a second integrated circuit at a surface of the second semiconductor substrate; and

a second dielectric layer underlying the second integrated circuit, wherein the first dielectric layer is physically bonded to the second dielectric layer, and wherein the second dielectric layer comprises a second dielectric material different from the first dielectric material, wherein the first dielectric layer and the second dielectric layer form an interface layer, and the interface layer has a thickness smaller than about 80 Å.

14. The package of claim 13 , wherein each of the first dielectric material and the second dielectric material comprises silicon and a material selected from the group consisting of oxygen, carbon, nitrogen, and combinations thereof.

15. The package of claim 13 further comprising:

a first bond pad in the first die; and

a second bond pad in the second die, wherein the first bond pad is bonded to the second bond pad through metal-to-metal direct bonding.

16. The method of claim 4 , wherein the fusion bonding comprises forming Si—O—Si bonds to join the first dielectric layer to the second dielectric layer.

17. The package of claim 9 , wherein the first dielectric layer is bonded to the second dielectric layer through Si—O—Si bonds.

18. The package of claim 13 , wherein the first dielectric layer is bonded to the second dielectric layer through Si—O—Si bonds.

19. The method of claim 1 , wherein the first package component is bonded to the second package component through die-on-wafer bonding.

20. The method of claim 1 , wherein the first package component is bonded to the second package component through wafer-on-wafer bonding.